Abert's sanvitalia (Sanvitalia abertii)
Abrams' alumroot (Heuchera abramsii)
Abrams' spurge (Euphorbia abramsiana)
Abronia, Coville's dwarf (Abronia nana var. covillei)
Acacia,
    Catclaw (Senegalia greggii)
    Plume (Albizia lophantha)*
    Sweet (Vachellia farnesiana var. farnesiana)*
Acton encelia (Encelia actoni)
Adams' manzanita (Arctostaphylos glandulosa ssp. adamsii)
Adder's-tongue, California (Ophioglossum californicum)
Adobe popcorn flower (Plagiobothrys acanthocarpus)
Adobe yampah (Perideridia pringlei)
Adolphia, California (Adolphia californica)
African asparagus fern (Asparagus asparagoides)*
African daisy (Dimorphotheca ecklonis)*
African mustard (Strigosella africana)*
Agave,
    Desert (Agave deserti var. deserti)
    Shaw's (Agave shawii var. shawii)
    Single-rosetted desert (Agave deserti var. simplex)
    Utah (Agave utahensis)
Agoura dudleya (Dudleya cymosa ssp. agourensis)
Alaska rein orchid (Piperia unalascensis)
Alder, White (Alnus rhombifolia)
Aleppo pine (Pinus halepensis)*
Alfalfa (Medicago sativa)*
Algodones Dunes sunflower (Helianthus niveus ssp. tephrodes)
Alkali buttercup (Ranunculus cymbalaria)
Alkali draba (Cusickiella douglasii)
Alkali goldenbush
    Bracted (Isocoma acradena var. bracteosa)
    Solitary-leaved (Isocoma acradenia var. eremophila)
Alkali heath (Frankenia salina)
Alkali mallow (Malvella leprosa)
Alkali mariposa lily (Calochortus striatus)
Alkali marsh aster (Almutaster pauciflorus)
Akali phacelia (Phacelia neglecta)
Alkali sacaton (Sporobolus airoides)
Alkali weed (Cressa truxillensis)
Allen's daisy (Pentachaeta aurea ssp. allenii)
Allseed, Four-leaf (Polycarpon tetraphyllum var. tetraphyllum)*
Almond, Desert (Prunus fasciculata var. fasciculata)
Alpine aster (Oreostemma alpigenum var. andersonii)
Alpine gold hulsea (Hulsea algida)
Alpine pearlwort (Sagina saginoides)
Alpine pussytoes (Antennaria media)
Alpine shooting star (Primula tetrandra)
Alpine sulphur-flowered buckwheat (Eriogonum umbellatum var. minus)
Alumroot,
    Abrams' (Heuchera abramsii)
    Elegant (Heuchera caespitosa)
    Island (Heuchera maxima)
    Mount Laguna (Heuchera brevistaminea)
    Pink (Heuchera rubescens)
    San Bernardino Mountains (Heuchera parishii)
    Shaggy-haired (Heuchera hirsutissima)
Alverson's spinystar (Coryphantha alversonii)
Alyssum,
    Desert (Lepidium fremontii)
    Sweet (Lobularia maritima)*
Amaranth,
    California (Amaranthus californicus)
    Fringed (Amaranthus fimbriatus)
    Pigweed (Amaranthus albus)*
    Torrey's (Amaranthus torreyi)
Amargosa nitrophila (Nitrophila mohavensis)
Ambrosia, San Diego (Ambrosia pumila)
American bulrush (Schoenoplectus americanus)
American dogwood (Cornus sericea ssp. sericea)
American rock-brake (Cryptogramma acrostichoides)
American speedwell (Veronica americana)
American vetch (Vicia americana ssp. americana)
American wild carrot (Daucus pusillus)
Ammannia, Red (Ammannia coccinea)
Amsonia, Woolly (Amsonia tomentosa)
Anderson's lupine (Lupinus andersonii)
Anderson's thornbush (Lycium andersonii)
Andrews' bedstraw (Galium andrewsii ssp. andrewsii)
Angelica, Woolly (Angelica tomentosa)
Angled-stem buckwheat (Eriogonum angulosum)
Annual bedstraw (Galium aparine)
Annual bur-sage (Ambrosia acanthicarpa)
Annual desert milkvetch (Astragalus aridus)
Annual malacothrix (Malacothrix clevelandii)
Annual moonwort (Lunaria annua)*
Annual mountain dandelion (Agoseris heterophylla var. heterophylla)
Annual rock-nettle (Eucnide rupestris)
Annual sandwort (Sabulina pusilla)
Antelope bush, see Desert bitterbrush
Apache plume (Fallugia paradoxa)
Appressed-fruited mountain tansy mustard (Descurainia incana)
Apricot, Desert (Prunus fremontii)
Apricot mallow (Sphaeralcea ambigua var. ambigua)
Apricot mallow, Rosy (Sphaeralcea ambigua var. rosacea)
Aralia, California (Aralia californica)
Arching rock-cress (Boechera arcuata)
Argus gilia (Gilia brecciarum ssp. neglecta)
Aridland goosefoot (Chenopodium desiccatum)
Arizona carlowrightia (Carlowrightia arizonica)
Arizona chalk dudleya (Dudleya arizonica)
Arizona herba impia (Logfia arizonica)
Arizona hymenoxys (Tetraneuris acaulis var. arizonica)
Arizona ipomopsis (Ipomopsis arizonica)
Arizona lupine (Lupinus arizonicus)
Arizona popcorn flower (Plagiobothrys arizonicus)
Arizona springparsley (Cymopterus multinervatus)
Arizona spurge (Euphorbia arizonica)
Arrowleaf (Pleurocoronis pluriseta)
Arrowleaf butterweed (Senecio triangularis)
Arrowleaf saltbush (Atriplex prostrata)*
Arrowscale (Stutzia covillei)
Arrow-weed (Pluchea sericea)
Arroyo lupine (Lupinus succulentus)
Arroyo willow (Salix lasiolepis)
Ash,
    California (Fraxinus dipetala)
    Velvet (Fraxinus velutina)
Ashy-gray paintbrush (Castilleja cinerea)
Ashy-leaf buckwheat (Eriogonum cinereum)
Ashy silktassel (Garrya flavescens)
Ashy spike-moss (Selaginella cinerascens)
Asian mustard, see Saharan mustard
Aster,
    Alkali marsh (Almutaster pauciflorus)
    Alpine (Oreostemma alpigenum var. andersonii)
    California (Corethrogyne filaginifolia)
    Chile (Symphyotrichum chilense)
    Desert hoary- (Dieteria canescens var. leucanthemifolia)
    Greata's (Symphyotrichum greatae)
    Hoary- (Dieteria canescens var. canescens)
    Laguna Mountains (Dieteria asteroides var. lagunensis)
    Long-leaved (Symphyotrichum ascendens)
    Mexican (Cosmos bipinnatus)*
    Mojave (Xylorhiza tortifolia var. tortifolia)
    San Bernardino (Symphyotrichum defoliatum)
    Scrub (Dieteria asteroides var. asteroides)
    Short-leaved cliff (Malacothrix saxatilis var. tenuifolia)
    Slim (Symphyotrichum subulatum var. parviflorum)
    Spiny (Chloracantha spinosa var. spinosa)
    Western lanceleaf (Symphyotrichum lanceolatum ssp. hesperium)
    Western mountain (Symphyotrichum spathulatum var. spathulatum)
    Ziegler's (Dieteria canescens var. ziegleri)
Asthmaweed (Erigeron sumatrensis)*
Athel (Tamarix aphylla)*
Athysanus, Dwarf (Athysanus pusillus)
Austin's beardtongue (Penstemon floridus var. austinii)
Australian brass buttons (Cotula australis)*
Australian pygmy weed (Crassula colligata ssp. lamprosperma)*
Australian saltbush (Atriplex semibaccata)*
Autumn dwarf gentian (Gentianella amarella ssp. acuta)
Aven Nelson's phacelia (Phacelia anelsonii)
Avens, Large-leaved (Geum macrophyllum var. perincisum)
Ayenia, California (Ayenia compacta)
Azalea, Western (Rhododendron occidentale)
Baby blue eyes,
    Eastwood's (Nemophila pulchella var. pulchella)
    Large-flower (Nemophila menziesii var. menziesii)
    Small-flower (Nemophila menziesii var. integrifolia)
Baby sun rose (Aptenia cordifolia)*
Baccharis,
    Broom (Baccharis sarothroides)
    Desert (Baccharis sergiloides)
    Emory, see Willow baccharis
    Encinitas (Baccharis vanessae)
    Malibu (Baccharis malibuensis)
    Plummer's (Baccharis plummerae ssp. plummerae)
    Salt marsh (Baccharis glutinosa)
    Willow (Baccharis salicina)
Bahia,
    Many-flowered (Picradeniopsis multiflora)
    Ragged-leaf (Hymenothrix dissecta)
Bailey's buckwheat (Eriogonum baileyi var. baileyi)
Baja birdbush (Ornithostaphylos oppositifolia)
Bajada lupine (Lupinus concinnus)
Baja navarretia (Navarretia peninsularis)
Bakersfield cactus (Opuntia basilaris var. treleasei)
Baldwin Lake linanthus (Linanthus killipii)
Ballhead ipomopsis (Ipomopsis congesta ssp. montana)
Balloon clover (Trifolium depauperatum var. truncatum)
Balsamroot, Deltoid (Balsamorhiza deltoidea)
Banana yucca (Yucca baccata var. baccata)
Banded volcanic gilia (Gilia ochroleuca ssp. bizonata)
Baneberry, Red (Actaea rubra)
Barberry,
    California (Berberis pinnata ssp. pinnata)
    Fremont's (Berberis fremontii)
    Nevin's (Berberis nevinii)
Barbwire Russian thistle (Salsola paulsenii)*
Barley,
    Bobtail (Hordeum intercedens)
    Foxtail (Hordeum murinum ssp. glaucum)*
    Hare (Hordeum murinum ssp. leporinum)*
    Meadow (Hordeum brachyantherum ssp. californicum)
Barrel cactus,
    California (Ferocactus cylindraceus)
    Coast (Ferocactus viridescens)
Barton Flats horkelia (Horkelia wilderae)
Basin butterweed (Packera multilobata)
Basin sagebrush (Artemisia tridentata ssp. tridentata)
Basket evening primrose (Oenothera deltoides ssp. deltoides)
Basket rush (Juncus textilis)
Bassia, Five-hook (Bassia hyssopifolia)
Bastard toadflax, California (Comandra umbellata ssp. californica)
Bastard-sage
    Knot-stemmed (Eriogonum wrightii var. nodosum)
    Ring-stemmed (Eriogonum wrightii var. membranaceum)
    Short-stemmed (Eriogonum wrightii var. subscaposum)
    Wright's (Eriogonum wrightii var. wrightii)
Bay, California (Umbellularia californica)
Beach morning glory (Calystegia soldanella)
Beach primrose,
    Channel Islands (Camissoniopsis cheiranthifolia ssp. cheiranthifolia)
    [Common] (Camissoniopsis cheiranthifolia ssp. suffruticosa)
Beach saltbush (Atriplex leucophylla)
Beaked penstemon (Penstemon rostriflorus)
Beard grass, Ditch (Polypogon interruptus)*
Bearded clover (Trifolium barbigerum)
Bearded cryptantha (Cryptantha barbigera var. barbigera)
Beardtongue,
    Austin's (Penstemon floridus var. austinii)
    California (Penstemon californicus)
    Cleveland's (Penstemon clevelandii var. clevelandii)
    Desert (Penstemon fruticiformis var. fruticiformis)
    Limestone (Penstemon calcareus)
    Mojave (Penstemon clevelandii var. mohavensis)
    San Bernardino (Penstemon caesius)
    San Gabriel (Penstemon labrosus)
    San Gabriel (yellow variant) (Penstemon labrosus)
    San Jacinto (Penstemon clevelandii var. connatus)
    Stephens' (Penstemon stephensii)
    Thompson's (Penstemon thompsoniae)
Beargrass,
    Chaparral (Nolina cismontana)
    [Common] (Nolina bigelovii)
Bear poppy (Arctomecon merriamii)
Bear Valley milkvetch (Astragalus lentiginosus var. sierrae)
Bear Valley pyrrocoma (Pyrrocoma uniflora var. gossypina)
Bear Valley sandwort (Eremogone ursina)
Bear Valley woollypod (Astragalus leucolobus)
Beautiful hulsea (Hulsea vestita ssp. callicarpha)
Beautiful rock-cress (Boechera pulchra)
Beavertail cactus,
    [Common] (Opuntia basilaris var. basilaris)
    Short-joint (Opuntia basilaris var. brachyclada)
Bedstraw,
    Andrews' (Galium andrewsii ssp. andrewsii)
    Annual (Galium aparine)
    Boxwood-leaved (Galium buxifolium)
    California (Galium californicum ssp. flaccidum)
    Catalina Island (Galium catalinense)
    Climbing (Galium nuttallii ssp. nuttallii)
    Dwarf three-petal (Galium trifidum ssp. subbiflorum)
    Graceful (Galium porrigens var. porrigens)
    Hilend's bedstraw (Galium hilendiae ssp. hilendiae)
    Island leafy (Galium angustifolium ssp. foliosum)
    Jepson's (Galium jepsonii)
    Johnston's (Galium johnstonii)
    Naked-stem (Galium angustifolium ssp. nudicaule)
    Narrow-leaved (Galium angustifolium ssp. angustifolium)
    Nodding (Galium hallii)
    Nuttall's island (Galium nuttallii ssp. insulare)
    Parish's (Galium parishii)
    Phlox-leaved (Galium andrewsii ssp. intermedium)
    San Antonio Canyon (Galium angustifolium ssp. gabrielense)
    San Gabriel bedstraw (Galium grande)
    San Jacinto Mountains (Galium angustifolium ssp. jacinticum)
    San Miguel Island (Galium californicum ssp. miguelense)
    Slender (Galium angustifolium ssp. gracillimum)
    Sprawling three-petal (Galium trifidum ssp. columbianum)
    Star-flowered (Galium stellatum)
    Tiny (Galium murale)*
    Twinleaf (Galium bifolium)
    Wall (Galium parisiense)*
    Wright's (Galium wrightii)
Bee balm (Monarda pectinata)
Bee blossom, Wavyleaf (Gaura sinuata)*
Beet, Common (Beta vulgaris)*
Beetle spurge (Euphorbia eriantha)
Beggar-ticks,
    Common (Bidens pilosa)*
    Smooth (Bidens laevis)
Bell gilia (Linanthus campanulatus)
Bentgrass,
    Green (Agrostis viridis)*
    Idaho (Agrostis idahoensis)
    Seashore (Agrostis pallens)
Bentham lupine (Lupinus benthamii)
Bent-stem monkeyflower (Erythranthe geniculata)
Bergamot mint (Mentha Xpiperita)*
Bermuda buttercup (Oxalis pes-caprae)*
Bermuda grass (Cynodon dactylon)*
Bernardia (Bernardia incana)
Bicolored yerba santa (Eriodictyon crassifolium var. nigrescens)
Biennial cinquefoil (Potentilla biennis)
Big Bear checkerbloom (Sidalcea pedata)
Big Bear Valley phlox (Phlox dolichantha)
Big-berry manzanita (Arctostaphylos glauca)
Big-bract verbena (Verbena bracteata)
Big-cone douglas fir (Pseudotsuga macrocarpa)
Bigelow's coreopsis (Leptosyne bigelovii)
Bigelow's desert four o'clock, see Desert wishbone bush
Bigelow's linanthus (Linanthus bigelovii ssp. johnsonii)
Bigelow's monkeyflower (Diplacus bigelovii var. bigelovii)
Bigelow's sneezeweed (Helenium bigelovii)
Bigelow's spike-moss (Selaginella bigelovii)
Big galleta grass (Hilaria rigida)
Big-leaf maple (Acer macrophyllum)
Big-leaf mistletoe (Phoradendron leucarpum ssp. macrophyllum)
Big-leaved crownbeard (Verbesina dissita)
Big-pod ceanothus (Ceanothus megacarpus var. megacarpus)
Bindweed
    Coast range (Calystegia collina ssp. venusta)
    [Common] (Convolvulus arvensis)*
Birch-leaf mountain-mahogany (Cercocarpus betuloides var. betuloides)
Birdnest buckwheat (Eriogonum nidularium)
Bird's beak,
    Bristly (Cordylanthus rigidus ssp. setiger)
    Nevin's (Cordylanthus nevinii)
    Orcutt's (Dicranostegia orcuttiana)
    Purple (Cordylanthus parviflorus)
    Salt marsh (Chloropyron maritimum ssp. maritimum)
    Stiffbranch (Cordylanthus rigidus ssp. rigidus)
    Tecopa (Chloropyron tecopense)
Birdseye gilia (Gilia tricolor ssp. diffusa)
Bird's-foot fern (Pellaea mucronata var. mucronata)
Bird's-foot trefoil,
    Canyon (Acmispon argyraeus var. argyraeus)
    [Common] (Lotus corniculatus)*
    River bar (Acmispon denticulatus)
    San Clemente Island (Acmispon argophyllus var. adsurgens)
    Santa Cruz Island (Acmispon argophyllus var. niveus)
Bishop pine (Pinus muricata)
Bistort, Western (Bistorta bistortoides)
Bitter cherry (Prunus emarginata)
Bitter cress (Cardamine oligosperma)
Bitter gooseberry (Ribes amarum)
Bitterroot (Lewisia rediviva var. minor)
Black-banded rabbitbrush (Ericameria paniculata)
Blackberry, California (Rubus ursinus)
Blackbrush (Coleogyne ramosissima)
Black cottonwood (Populus trichocarpa)
Black grama (Bouteloua eriopoda)
Black hair nettle (Hesperocnide tenella)
Black locust (Robinia pseudoacacia)*
Black medick (Medicago lupulina)*
Black mustard (Brassica nigra)*
Black oak, California (Quercus kelloggii)
Black sage (Salvia mellifera)
Black sagebrush (Artemisia nova)
Black sedge (Schoenus nigricans)
Black walnut,
    California (female flowers) (Juglans californica)
    California (male flowers) (Juglans californica)
Black willow, Goodding's (Salix gooddingii)
Bladderpod,
    [Common] (Peritoma arborea var. arborea)
    King's (Physaria kingii ssp. kingii)
    Round-fruited (Peritoma arborea var. globosa)
    San Bernardino Mountains (Physaria kingii ssp. bernardina)
Bladder senna (Colutea arborescens)*
Blair's munzothamnus (Munzothamnus blairii)
Blazing star,
    Bushy (Mentzelia dispersa)
    Clustered (Mentzelia congesta)
    Giant (Mentzelia laevicaulis)
    Hairy (Mentzelia hirsutissima)
    Inyo (Mentzelia oreophila)
    Jones' (Mentzelia jonesii)
    Lindley's (Mentzelia lindleyi)
    Mountain (Mentzelia montana)
    Pacific (Mentzelia obscura)
    Polished (Mentzelia polita)
    Reflexed (Mentzelia reflexa)
    Sand (Mentzelia involucrata)
    Veatch's (Mentzelia veatchiana)
    Whitestem (Mentzelia albicaulis)
Bleeding hearts (Ehrendorferia ochroleuca)
Blessed thistle (Centaurea benedictus)*
Blow wives (Achyrachaena mollis)
Bluebells, Desert (Phacelia campanularia)
Bluecup,
    San Gabriel (Githopsis diffusa ssp. diffusa)
    White-flowered (Githopsis diffusa ssp. candida)
Bluecurls,
    Hidden Lake (Trichostema austromontanum ssp. compactum)
    Parish's (Trichostema parishii)
    Smallflower (Trichostema micranthum)
    Southern (Trichostema austromontanum ssp. austromontanum)
    Woolly (Trichostema lanatum)
Blue dicks
    [Common] (Dipterostemon capitatus ssp. capitatus)
    Few-flowered (Dipterostemmon capitatus ssp. pauciflorus)
Blue-eyed grass,
    [Common] (Sisyrinchium bellum)
    Death Valley (Sisyrinchium funereum)
    Idaho (Sisyrinchium idahoense var. occidentale)
    Nevada (Sisyrinchium halophilum)
Blue flag, Western (Iris missouriensis)
Blue flax, Western (Linum lewisii var. lewisii)
Blue grama (Bouteloua gracilis)
Bluegrass,
    Bulbous (Poa bulbosa ssp. vivipara)*
    Fendler's (Poa fendleriana ssp. longiligula)
    Kentucky (Poa pratensis ssp. pratensis)*
    One-sided (Poa secunda ssp. secunda)
    Rush (Poa secunda ssp. juncifolia)
    San Bernardino (Poa atropurpurea)
    Sand-dune (Poa douglasii)
    Weak (Poa infirma) *
Blue gum (Eucalyptus globulus)*
Blue larkspur (Delphinium parryi ssp. parryi)
Blue oak (Quercus douglasii)
Blue sage (Salvia dorrii var. dorrii)
Blue sage, Hairy (Salvia dorrii var. pilosa)
Blue toadflax (Nuttallanthus texanus)
Blue violet, see Western dog violet
Blue wildrye (Elymus glaucus ssp. glaucus)
Blue-witch nightshade (Solanum umbelliferum)
Bluish spike-moss (Selaginella asprella)
Bluntleaf yellowcress (Rorippa curvipes)
Bobtail barley (Hordeum intercedens)
Boccone's sand-spurrey (Spergularia bocconi)*
Bog orchid,
    Sparse-flowered (Platanthera sparsiflora)
    White-flowered (Platanthera dilatata var. leucostachys)
Bog wintergreen (Pyrola asarifolia ssp. asarifolia)
Bog yellow-cress, Western (Rorippa palustris ssp. palustris)
Boisduvalia, Smooth (Epilobium campestre)
Bolander's monkeyflower (Diplacus bolanderi)
Bolander's quillwort (Isoetes bolanderi)
Bolander's sedge (Carex bolanderi)
Bolander's woodland star (Lithophragma bolanderi)
Bolle's mistletoe (Phoradendron bolleanum)
Booth's clustered evening primrose (Eremothera boothii ssp. condensata)
Booth's desert evening primrose (Eremothera boothii ssp. desertorum)
Booth's intermediate evening primrose (Eremothera boothii ssp. intermedia)
Booth's shredding evening primrose (Eremothera boothii ssp. decorticans)
Borrego milkvetch (Astragalus lentiginosus var. borreganus)
Botany woman's threadplant (Nemacladus twisselmannii var. botanywomaniae)
Boundary goldenbush (Ericameria brachylepis)
Bowlesia (Bowlesia incana)
Bownut cryptantha (Oreocarya abortiva)
Box elder (Acer negundo)
Boxthorn,
    California (Lycium californicum)
    Cooper's (Lycium cooperi)
Boxwood-leaved bedstraw (Galium buxifolium)
Boykinia,
    Coast (Boykinia occidentalis)
    Round-leaved (Boykinia rotundifolia)
Bracken fern (Pteridium aquilinum var. pubescens)
Bracted alkali goldenbush (Isocoma acradena var. bracteosa)
Brake, Cliff (Pellaea truncata)
Branched hareleaf (Lagophylla ramosissima)
Branching phacelia  (Phacelia ramosissima)
Brandegea (Brandegea bigelovii)
Brandegee's sage (Salvia brandegeei)
Brass-buttons,
    Australian (Cotula australis)*
    [Common] (Cotula coronopifolia)*
Braunton's rattleweed (Astragalus brauntonii)
Brazilian pepper (Schinus terebinthifolius)*
Brewer's cliffbrake (Pellaea breweri)
Brewer's fleabane (Erigeron breweri var. breweri)
Brewer's fleabane, Mojave (Erigeron breweri var, porphyreticus)
Brewer's lupine (Lupinus breweri var. breweri)
Brewer's monardella (Monardella breweri ssp. breweri)
Brewer's monkeyflower (Erythranthe breweri)
Brewer's navarretia (Navarretia breweri)
Brewer's oak (Quercus garryana var. breweri)
Brewer's red maids (Calandrinia breweri)
Brickellbush,
    California (Brickellia californica)
    Desert (Brickellia desertorum)
    Gum-leaved (Brickellia longifolia var. multiflora)
    Knapp's (Brickellia knappiana)
    Little-leaved (Brickellia microphylla var. microphylla)
    Narrow-leaved (Brickellia oblongifolia var. linifolia)
    Nevin's (Brickellia nevinii)
    Shrubby (Brickellia frutescens)
    Spearleaf (Brickellia atractyloides var. arguta)
    Woolly (Brickellia incana)
Bridges' gilia (Navarretia leptalea ssp. bicolor)
Bright white (Prenanthella exigua)
Bristlecone pine (Pinus longaeva)
Bristly bird's beak (Cordylanthus rigidus ssp. setiger)
Bristly fiddleneck (Amsinckia tessellata var. gloriosa)
Bristly golden-aster (Heterotheca sessiliflora ssp. echioides)
Bristly langloisia (Langloisia setosissima ssp. setosissima)
Bristly-leaved rock-cress (Boechera rectissima)
Bristly matilija poppy (Romneya trichocalyx)
Bristly mousetail (Myosurus apetalus var. montanus)
Bristly ox-tongue (Helminthotheca echioides)*
Bristly pectocarya (Pectocarya setosa)
Brittlebush (Encelia farinosa)
Brittle fern (Cystopteris fragilis)
Brittle sandwort (Sabulina nuttallii var. gracilis)
Brittle spineflower (Chorizanthe brevicornu var. brevicornu)
Broad-flowered gilia (Gilia latiflora ssp. latiflora)
Broad-fruited pectocarya (Pectocarya platycarpa)
Broad-keeled milkvetch (Astragalus platytropis)
Broad-leaf gilia (Aliciella latifolia ssp. latifolia)
Broad-leaf plantain (Plantago major)*
Broad-leaf stonecrop (Sedum spathulifolium)
Broad-leaved cattail (Typha latifolia)
Broad-leaved lotus (Hosackia crassifolia var. crassifolia)
Broad-leaved lupine (Lupinus latifolius var. latifolius)
Broad-leaved stillingia (Stillingia spinulosa)
Broad-seeded rock-cress (Boechera platysperma)
Brodiaea,
    Earth (Brodiaea terrestris ssp. kernensis)
    Harvest (Brodiaea elegans)
    Orcutt's (Brodiaea orcuttii)
    Santa Rosa basalt (Brodiaea santarosae)
    Thread-leaved (Brodiaea filifolia)
Brome,
    California (Bromus sitchensis var. carinatus)
    Hall's (Bromus hallii)
    Mountain (Bromus sitchensis var. marginatus)
    Red (Bromus rubens)*
    Ripgut (Bromus diandrus)*
    Seaside (Bromus sitchensis var. maritimus)
Broom,
    Dune (Chaetadelpha wheeleri)
    French (Genista monspessulana)*
    Mediterranean (Genista linifolia*
    Portuguese (Cytisus striatus)*
    Spanish (Spartium junceum)*
    Turpentine- (Thamnosma montana)
Broom baccharis (Baccharis sarothroides)
Broom groundsel (Senecio spartioides)
Broom snakeweed (Gutierrezia sarothrae)
Broomrape,
    California (Aphyllon californicum ssp. feudgei)
    Chaparral (Aphyllon tuberosum)
    Clustered (Aphyllon fasciculatum)
    Cooper's (Aphyllon cooperi)
    Flat-topped (Aphyllon corymbosum)
    Naked (Aphyllon purpureum)
    Parish's (Aphyllon parishii ssp. parishii)
    Rock Creek (Aphyllon validum)
    Short-lobed (Aphyllon parishii ssp. brachylobum)
    Valley (Aphyllon vallicolum)
Brown-eyed primrose,
    Death Valley (Chylismia claviformis ssp. funerea)
    Mojave (Chylismia claviformis ssp. claviformis)
    Peirson's (Chylismia claviformis ssp. peirsonii)
Browneyes (Chylismia claviformis ssp. aurantiaca)
Brown-headed rush (Juncus phaeocephalus var. paniculatus)
Brown microseris (Stebbinsoseris heterocarpa)
Brown turbans (Malperia tenuis)
Buckbrush (Ceanothus cuneatus var. cuneatus)
Buckeye, California (Aesculus californica)
Buckhorn cholla (Cylindropuntia acanthocarpa var. acanthocarpa)
Buckwheat,
    Alpine suphur-flowered buckwheat (Eriogonum umbellatum var. minus)
    Angled-stem (Eriogonum angulosum)
    Ashy-leaf (Eriogonum cinereum)
    Bailey's (Eriogonum baileyi var. baileyi)
    Birdnest (Eriogonum nidularium)
    California wild (Eriogonum fasciculatum var. polifolium)
    Cithara wild (Eriogonum cithariforme var. cithariforme)
    Clark Mountains buckwheat (Eriogonum heermannii var. floccosum)
    Coastal California (Eriogoncoastalum fasciculatum var. fasciculatum)
    Conejo (Eriogonum crocatum)
    Cottony wild (Eriogonum gossypinum)
    Cushenbury (Eriogonum ovalifolium var. vineum)
    Davidson's (Eriogonum davidsonii)
    Dune (Eriogonum deserticola)
    East Mojave (Eriogonum fasciculatum var. flavoviride)
    Few-flowered naked (Eriogonum nudum var. pauciflorum)
    Flatcrown (Eriogonum deflexum var. deflexum)
    Flat-topped (Eriogonum plumatella)
    Fort Mojave (Eriogonum ordii)
    Gilman's (Eriogonum gilmanii)
    Heermann's (Eriogonum heermannii var. argense)
    Island (Eriogonum grande var. grande)
    Johnston's (Eriogonum microtheca var. johnstonii)
    Jointed (Eriogonum intrafractum)
    Kennedy's (Eriogonum     kennedyi var. kennedyi)
    Knotty (Eriogonum wrightii var. nodosum)
    Kidneyleaf (Eriogonum reniforme)
    Leafy (Eriogonum fasciculatum var. foliolosum)
    Longstem (Eriogonum elongatum var. elongatum)
    Munz's (Eriogonum umbellatum var. munzii)
    Nevada (Eriogonum umbellatum var. nevadense)
    Oval-leaved (Eriogonum ovalifolium var. ovalifolium)
    Palmer's (Eriogonum palmerianum)
    Panamint (Eriogonum panamintense)
    Parish's (Eriogonum parishii)
    Parry's wild (Eriogonum brachypodum)
    Pineland (Eriogonum molestum)
    Red-flowered (Eriogonum grande var. rubescens)
    Reveal's (Eriogonum contiguum)
    Rixford's (Eriogonum rixfordii)
    Robust Hoffmann's (Eriogonum hoffmannii var. robustius)
    Rock (Eriogonum saxatile)
    Rose-and-white (Eriogonum gracillimum)
    San Bernardino (Eriogonum microthecum var. corymbosoides)
    San Jacinto (Eriogonum apiculatum)
    Santa Barbara Island (Eriogonum giganteum var. compactum)
    Santa Cruz Island (Eriogonum arborescens)
    Santa Ynez wild (Eriogonum cithariforme var. agninum)
    Seacliff (Eriogonum parvifolium)
    Shortflower (Eriogonum brachyanthum)
    Simpson's (Eriogonum microthecum var. simpsonii)
    Slender (Eriogonum gracile var. gracile)
    Southern alpine (Eriogonum kennedyi var. alpigenum)
    Southern mountain (Eriogonum kennedyi var. austromontanum)
    Spotted (Eriogonum maculatum)
    Sulphur-flowered (Eriogonum umbellatum var. subaridum)
    Tehachapi (Eriogonum callistum)
    Thomas' (Eriogonum thomasii)
    Thorne's (Eriogonum thornei)
    Thurber's (Eriogonum thurberi)
    Varicolored (Eriogonum umbellatum var. versicolor)
    Wand (Eriogonum roseum)
    Weston's (Eriogonum nudum var. westonii)
    White Mountains (Eriogonum gracilipes)
    Wildrose Canyon (Eriogonum eremicola)
    Wright's, see Bastard-sage
Budsage (Artemisia spinescens)
Buffalo-berry (Shepherdia argentea)
Bulbous bluegrass (Poa bulbosa ssp. vivipara)*
Bull mallow (Malva nicaeensis)*
Bull thistle (Cirsium vulgare)*
Bulrush,
    American (Schoenoplectus americanus)
    California (Schoenoplectus californicus)
    Marsh (Bolboschoenus maritimus ssp. paludosus)
    Panicled (Scirpus microcarpus)
Bur-chervil (Anthriscus caucalis)*
Burhead (Echinodorus berteroi)
Burlew's onion (Allium burlewii)
Burning bush (Euonymus occidentalis var. parishii)
Burrobush (Ambrosia dumosa)
Bur-sage,
    Annual (Ambrosia acanthicarpa)
    Goosefoot (Ambrosia chenopodiifolia)
    Holly-leaved (Ambrosia ilicifolia)
    Woolly (Ambrosia eriocentra)
Bush anemone (Carpenteria californica)*
Bush chinquapin (Chrysolepis sempervirens)
Bush-loving cryptantha (Cryptantha dumetorum)
Bush lupine,
    Coast (Lupinus arboreus)
    [Common] (Lupinus longifolius)
    Douglas's Silver (Lupinus albifrons var. douglasii)
    Hall's (Lupinus excubitus var. hallii)
    Johnston's (Lupinus excubitus var. johnstonii)
    Silver (Lupinus albifrons var. albifrons)
Bush mallow,
    [Common] (Malacothamnus fasciculatus var. fasciculatus)
    Davidson's (Malacothamnus davidsonii)
    Enigmatic (Malacothamnus enigmaticus)
    Fremont's (Malacothamnus fremontii)
    Many-flowered (Malacothamnus densiflorus)
    Round-leaved (Malacothamnus orbiculatus)
    San Clemente Island (Malacothamnus clementinus)
    Santa Cruz Island (Malacothamnus fasciculatus var. nesioticus)
Bush monkeyflower
    Cleveland's (Diplacus clevelandii)
    Hairy (Diplacus longiflorus)
    Island (Diplacus parviflorus)
    Low (Diplacus aridus)
    Red (Diplacus puniceus)
    Southern (Diplacus australis)
    Southern Sierra (Diplacus calycinus)
Bush muhly (Muhlenbergia porteri)
Bush poppy (Dendromecon rigida)
Bushrue (Cneoridium dumosum)
Bush senecio (Senecio flaccidus var. douglasii)
Bush spurge (Euphorbia characias)*
Bush sunflower (Encelia californica)
Bushy blazing star (Mentzelia dispersa)
Bushy cryptantha (Johnstonella racemosa)
Buttercup,
    Alkali (Ranunculus cymbalaria)
    Bermuda (Oxalis pes-caprae)*
    California (Ranunculus californicus var. californicus)
    Delicate (Ranunculus hebecarpus)
    Eschscholtz's (Ranunculus eschscholtzii var. oxynotus)
    Small water-plantain (Ranunculus alismifolius)
    Water (Ranunculus aquatilis var. diffusus)
    Western (Ranunculus occidentalis)
Butterfly bush, Panamint (Buddleja utahensis)
Butterfly mariposa lily (Calochortus venustus)
Butterweed,
    Arrowleaf (Senecio triangularis)
    Basin (Packera multilobata)
Button-celery, San Diego (Eryngium aristulatum var. parishii)
Cabbage, Mediterranean (Brassica fruticulosa)
Cactus,
    Bakersfield (Opuntia basilaris var. treleasei)
    Beavertail (Opuntia basilaris var. basilaris)
    California barrel cactus (Ferocactus cylindraceus var. cylindraceus)
    Coast barrel (Ferocactus viridescens)
    Cottontop (Echinocactus polycephalus var. polycephalus)
    Engelmann's hedgehog (Echinocereus englemannii)
    Fishhook (Mammillaria tetrancistra)
    Johnson's bee-hive (Sclerocactus johnsonii)
    Mission (Opuntia ficus-indica)*
    Mojave fishhook (Sclerocactus polyancistrus)
    Mojave mound (Echinocereus mojavensis)
    Mojave prickly-pear (Opuntia polyacantha var. erinacea)
    Strawberry (Mammillaria dioica)
Calabazilla (Cucurbita foetidissima)
Caleb saltbush (Atriplex canescens var. laciniata)
Calicoflower, Toothed (Downingia cuspidata)
Calico monkeyflower (Diplacus pictus)
California adder's-tongue (Ophioglossum californicum)
California adolphia (Adolphia californica)
California amaranth (Amaranthus californicus)
California aralia (Aralia californica)
California ash (Fraxinus dipetala)
California-aster (Corethrogyne filaginifolia)
California ayenia (Ayenia compacta)
California barberry (Berberis pinnata ssp. pinnata)
California barrel cactus (Ferocactus cylindraceus)
California bastard toadflax (Comandra umbellata ssp. californica)
California bay (Umbellularia californica)
California beardtongue (Penstemon californicus)
California bedstraw (Galium californicum ssp. flaccidum)
California blackberry (Rubus ursinus)
California black oak (Quercus kelloggii)
California black walnut (male flowers) (Juglans californica)
California black walnut (female flowers) (Juglans californica)
California boxthorn (Lycium californicum)
California breadroot (Pediomelum californicum)
California brickellbush (Brickellia californica)
California brome (Bromus carinatus var. carinatus)
California broomrape (Aphyllon californicum ssp. feudgei)
California buckeye (Aesculus californica)
California bulrush (Schoenoplectus californicus)
California bur-clover (Medicago polymorpha)*
California buttercup (Ranunculus californicus var. californicus)
California chicory (Rafinesquia californica)
California cliff brake (Pellaea mucronata var. californica)
California cloak fern (Notholaena californica)
California copperleaf (Acalypha californica)
California croton (Croton californicus)
California dandelion (Taraxacum californicum)
California dodder (Cuscuta californica var. californica)
California dodder, Short-flowered (Cuscuta californica var. breviflora)
California draba (Draba cuneifolia)
California ephedra (Ephedra californica)
California evening primrose (Oenothera californica ssp. californica)
California everlasting (Pseudognaphalium californicum)
California false-indigo (Amorpha californica var. californica)
California false pennyroyal (Hedeoma nana ssp. californica)
California fan palm (Washingtonia filifera)
California fiddleleaf (Nama californica)
California figwort (Scrophularia californica)
California filago (Logfia filaginoides)
California fuchsia (Epilobium canum ssp. latifolium)
California geranium (Geranium californicum)
California goldenrod (Solidago velutina ssp. californica)
California goldfields (Lasthenia californica ssp. californica)
California goosefoot (Chenopodium californicum)
California groundcone (Kopsiopsis strobilacea)
California groundsel (Senecio californicus)
California hedge-nettle (Stachys bullata)
California hedge-parsley (Yabea microcarpa)
California hesperochiron (Hesperochiron nanus)
California huckleberry (Vaccinium ovatum)
California indigo bush (Psorothamnus arborescens var. simplicifolius)
California juniper (Juniperus californica)
California kallstroemia (Kallstroemia californica)
California lace fern (Aspidotis californica)
California lomatium (Lomatium californicum)
California loosestrife (Lythrum californicum)
California lotus (Acmispon wrangelianus)
California maidenhair fern (Adiantum jordanii)
California malacothrix (Malacothrix californica)
California man-root (Marah fabacea)
California marina (Marina orcuttii var. orcuttii)
California matchweed (Gutierrezia californica)
California milkweed (Asclepias californica)
California mustard (Caulanthus lasiophyllus)
California oxalis (Oxalis californica)
California pink (Silene laciniata ssp. californica)
California plantain (Plantago erecta)
California polypody (Polypodium californicum)
California popcorn flower (Plagiobothrys collinus var. fulvescens)
California poppy (Eschscholzia californica)
California rock-cress (Boechera californica)
California sagebrush (Artemisia californica)
California saltbush (Extriplex californica)
California satintail (Imperata brevifolia)
California sawgrass (Cladium californicum)
California saxifrage (Micranthes californica)
California sea-pink (Armeria maritima ssp. californica)
California spineflower (Mucronea californica)
California squirreltail (Elymus elymoides ssp. californicus)
California sun cup (Eulobus californicus)
California sunflower (Helianthus californicus)
California tea (Rupertia physodes)
California thistle (Cirsium occidentale var. californicum)
California tickseed (Leptosyne californica)
California trixis (Trixis californica var. californica)
California wax-myrtle (Morella californica)
California wild buckwheat (Eriogonum fasciculatum var. polifolium)
Caltha-leaved phacelia (Phacelia calthifolia)
Caltrop, Few-flowered (Kallstroemia parviflora)
Campion, Menzies' (Silene menziesii)
Cancerwort, Sharpleaf (Kickxia elatine)*
Canchalagua (Zeltnera venusta)
Candleholder dudleya (Dudleya candelabrum)
Cane beardgrass (Bothriochloa barbinodis)
Cane cholla, see valley cholla
Canterbury bells (Phacelia minor)
Canyon bird's-foot trefoil (Acmispon argyraeus var. argyraeus)
Canyon clarkia (Clarkia epilobioides)
Canyon dodder (Cuscuta subinclusa)
Canyon dudleya (Dudleya cymosa ssp. cymosa)
Canyon live oak (Quercus chrysolepis)
Canyon silktassel (Garrya veatchii)
Canyon sunflower (Venegasia carpesioides)
Canyon sweet pea (Lathyrus vestitus var. vestitus)
Cape-ivy (Delairea odorata)*
Caper spurge (Euphorbia lathyris)*
Caraway-leaved gilia (Saltugilia caruifolia)
Caraway-leaved lomatium (Lomatium caruifolium var. caruifolium)
Cardoon (Cynara cardunculus ssp. flavescens)*
Carlowrightia, Arizona (Carlowrightia arizonica)
Carolina geranium (Geranium carolinianum)
Carpet clover, Grant's (Trifolium monanthum var. grantianum)
Carpet-weed, Threadstem (Mollugo cerviana)
Carrizo Mountain spurge (Euphorbia pediculifera)
Castor bean (Ricinus communis)*
Catalina cherry (Prunus ilicifolia ssp. lyonii)
Catalina crossosoma (Crossosoma californicum)
Catalina Island bedstraw (Galium catalinense)
Catalina Island mountain-mahogany (Cercocarpus traskiae)
Catalina mariposa lily (Calochortus catalinae)
Catchfly,
    Krantz's (Silene krantzii)
    Lemmon's (Silene lemmonii)
    Many-nerved (Silene multiflora)
    Palmer's (Silene bernardina)
    Parish's (Silene parishii)
    Sleepy (Silene antirrhina)
    White (Silene verecunda)
Catchfly gentian (Eustoma exaltatum ssp. exaltatum)
Catclaw acacia (Senegalia greggii)
Caterpillar phacelia (Phacelia cicutaria var. hispida)
Catnip (Nepeta cataria)*
Cat's ear,
    Rough (Hypochaeris radicata)*
    Smooth (Hypochaeris glabra)*
Cattail,
    Broad-leaved (Typha latifolia)
    Southern (Typha domingensis)
Cattle spinach (Atriplex polycarpa)
Caulanthus,
    Clasping-leaved (Caulanthus amplexicaulis)
    Hall's (Caulanthus hallii)
Cave evening primrose (Oenothera cavernae)
Ceanothus,
    Big-pod (Ceanothus megacarpus var. megacarpus)
    Cupleaf (Ceanothus perplexans)
    Greenbark (Ceanothus spinosus)
    Hairy (Ceanothus oliganthus)
    Hoaryleaf (Ceanothus crassifolius var. crassifolius)
    Island (Ceanothus arboreus)
    Lakeside (Ceanothus cyaneus)
    Mojave (Ceanothus pauciflorus)
    Palmer's (Ceanothus palmeri)
    Wartleaf (Ceanothus papillosus)
    Wartstem (Ceanothus verrucosus)
    Woollyleaf (Ceanothus tomentosus)
Cedar, Incense (Calocedrus decurrens)
Celery,
    Common (Apium graveolens)*
    Wild (Apiastrum angustifolium)
Century plant (Agave americana)*
Cereal rye (Secale cereale)*
Cereus, Golden-spined (Bergerocactus emoryi)
Chaffbush (Amphipappus fremontii var. fremontii)
Chaffweed, Common (Lysimachia minima)
Chalk dudleya (Dudleya pulverulenta)
Chamise
    [Common] (Adenostoma fasciculatum var. fasciculatum)
    San Diego (Adenostoma fasciculatum var. obtusifolium)
Chamomile, Globe (Oncosiphon piluliferum)*
Changeable phacelia (Phacelia mutabilis)
Channel Islands beach primrose (Camissoniopsis cheiranthifolia ssp. cheiranthifolia)
Channel Island scrub oak (Quercus pacifica)
Channel Island tree poppy (Dendromecon harfordii)
Chaparral beargrass (Nolina cismontana)
Chaparral broomrape (Aphyllon tuberosum)
Chaparral currant (Ribes malvaceum var. viridifolium)
Chaparral gilia (Gilia angelensis)
Chaparral honeysuckle (Lonicera interrupta)
Chaparral pea,
    [Common] (Pickeringia montana var. montana)
    Woolly (Pickeringia montana var. tomentosa)
Chaparral prickly-pear (Opuntia oricola)
Chaparral sand-verbena (Abronia villosa var. aurita)
Chaparral whitethorn (Ceanothus leucodermis)
Chaparral yucca (Hesperoyucca whipplei)
Charlotte's phacelia (Phacelia nashiana)
Cheat grass (Bromus tectorum)*
Checkerbloom,
    Big Bear (Sidalcea pedata)
    Dwarf (Sidalcea malviflora ssp. dolosa)
    Few-leaved (Sidalcea sparsifolia)
    Island (Sidalcea malviflora ssp. malviflora)
Checker fiddleneck (Amsinckia tessellata var. tessellata)
Cheesebush (Ambrosia salsola var. salsola)
Cheeseweed (Malva parviflora)*
Cherry,
    Bitter (Prunus emarginata)
    Catalina (Prunus ilicifolia ssp. lyonii)
    Hollyleaf (Prunus ilicifolia ssp. ilicifolia)
Chess,
    Chilean (Bromus berteroanus)
    Soft (Bromus hordeaceus)*
Chia (Salvia columbariae)
Chicalote (Argemone munita)
Chick lupine (Lupinus microcarpus var. horizontalis)
Chickweed,
    [Common] (Stellaria media)*
    Mouse-ear (Cerastium glomeratum)*
    Perennial (Cerastium fontanum ssp. vulgare)*
    Shining (Stellaria nitens)
    Water (Montia fontana)
Chickweed oxytheca (Sidotheca caryophylloides)
Chicory,
    California (Rafinesquia californica)
    [Common] (Cichorium intybus)*
    Desert (Rafinesquia neomexicana)
Chicory-leaved stephanomeria (Stephanomeria cichoriacea)
Child's collinsia (Collinsia childii)
Chilean chess (Bromus berteroanus)
Chile aster (Symphyotrichum chilense)
Chinchweed, see Golden chinch flower
Chinese houses,
    [Common] (Collinsia heterophylla var. heterophylla)
    Southern (Collinsia concolor)
    Sticky (Collinsia tinctoria)
Chinquapin, Bush (Chrysolepis sempervirens)
Chocolate lily (Fritillaria biflora var. biflora)
Chokecherry, Western (Prunus virginiana var. demissa)
Cholla,
    Buckhorn (Opuntia acanthocarpa var. acanthocarpa)
    Cane, see Valley cholla
    Coast (Opuntia prolifera)
    Fosberg's (Cylindropuntia fosbergii)
    Gander's (Cylindropuntia ganderi)
    Jumping (Opuntia bigelovii)
    Mat (Grusonia parishii)
    Munz's (Cylindropuntia munzii)
    Pencil (Opuntia ramosissima)
    Silver (Opuntia echinocarpa)
    Valley (Cylindropuntia bernardina)
    Wolf's (Opuntia wolfii)
Chorizanthe, Spiny, see Rigid spineflower
Chuparosa (Justicia californica)
Cima milkvetch
    [Common] (Astragalus cimae var. cimae)
    Inflated cima milkvetch (Astragalus cimae var. sufflatus)
Cinquefoil,
    Biennial (Potentilla biennis)
    Coastal sticky (Drymocallis glandulosa var. wrangelliana)
    Double-toothed sticky (Drymocallis glandulosa var. reflexa)
    Elmer's (Potentilla gracilis var. elmeri)
    Ewan's (Drymocallis cuneifolia var. ewanii
    Inland sticky (Drymocallis glandulosa var. glandulosa)
    Nevada (Drymocallis lactea var. lactea)
    Norwegian (Potentilla norvegica)*
    Silverleaf (Potentilla anserina ssp. anserina)
    Single-toothed sticky (Drymocallis glandulosa var. viscida)
    Slender (Potentilla gracilis var. fastigiata)
    Wheeler's (Potentilla wheeleri)
Cithara wild buckwheat (Eriogonum cithariforme var. cithariforme)
Clarkia,
    Canyon (Clarkia epilobioides)
    Club-fruited speckled (Clarkia cylindrica ssp. clavicarpa)
    Diamond-petalled (Clarkia rhomboidea)
    Dudley's (Clarkia dudleyana)
    Elegant (Clarkia unguiculata)
    Mountain (Clarkia heterandra)
    Punchbowl (Clarkia bottae)
    Purple (Clarkia purpurea ssp. quadrivulnera)
    Ramona (Clarkia similis)
    Red spot (Clarkia speciosa ssp. polyantha)
    Speckled (Clarkia cylindrica ssp. cylindrica)
Clark Mountains buckwheat (Eriogonum heermannii var. floccosum)
Clasping-leaved caulanthus (Caulanthus amplexicaulis)
Clasping pepperweed (Lepidium perfoliatum)*
Cleftleaf wild heliotrope (Phacelia crenulata var. crenulata)
Cleome, Naked (Cleome sparsifolia)
Cleveland's beardtongue (Penstemon clevelandii var. clevelandii)
Cleveland's bush monkeyflower (Diplacus clevelandii)
Cleveland's cryptantha (Cryptantha clevelandii)
Cleveland's horkelia (Horkelia clevelandii var. clevelandii)
Cleveland's lip fern (Myriopteris clevelandii)
Cleveland's muilla (Bloomeria clevelandii)
Cleveland's sage (Salvia clevelandii)
Cliff-aster, Short-leaved (Malacothrix saxatilis var. tenuifolia)
Cliff brake,
    Brewer's (Pellaea breweri)
    California (Pellaea mucronata var. californica)
    [Common] (Pellaea truncata)
Cliff malacothrix (Malacothrix saxatilis var. implicata)
Cliff rose (Purshia stansburyana)
Cliff spurge (Euphorbia misera)
Cliff sword fern (Polystichum imbricans ssp. curtum)
Climbing bedstraw (Galium nuttallii ssp. nuttallii)
Climbing milkweed (Funastrum cynanchoides var. hartwegii)
Cloak fern,
    California (Notholaena californica)
    Jones' (Argyrochosma jonesii)
    Scaly (Astrolepis cochisensis)
Clokey's gilia (Gilia clokeyi)
Clover,
    Balloon (Trifolium depauperatum var. truncatum)
    Bearded (Trifolium barbigerum)
    Creek (Trifolium obtusiflorum)
    Grant's carpet (Trifolium monanthum ssp. grantianum)
    Indian, see Rancheria clover
    Mountain (Trifolium wormskioldii)
    Mountain carpet (Trifolium monanthum ssp. monanthum)
    Pin-point (Trifolium gracilentum)
    Red (Trifolium pratense)*
    Rose (Trifolium hirtum)*
    Small-head field (Trifolium microcephalum)
    Spanish (Acmispon americanus var. americanus)
    Summer (Trifolium longipes ssp. hansenii)
    Tomcat (Trifolium willdenovii)
    Tree (Trifolium ciliolatum)
    White (Trifolium repens)*
    Whitetip (Trifolium variegatum)
Clover fern (Marsilea vestita ssp. vestita)
Club-fruited speckled clarkia (Clarkia cylindrica ssp. clavicarpa)
Clustered blazing star (Mentzelia congesta)
Clustered field sedge (Carex praegracilis)
Clustered tidy lupine (Lupinus lepidus var. confertus)
Clustered toad rush (Juncus bufonius var. congestus)
Coastal California buckwheat (Eriogonum fasciculatum var. fasciculatum)
Coastal gumplant (Grindelia stricta var. platyphylla)
Coastal lotus (Acmispon maritimus var. maritimus)
Coastal scrub oak (Quercus dumosa)
Coastal silverback fern (Pentagramma viscosa)
Coastal sticky cinquefoil (Drymocallis glandulosa var. wrangelliana)
Coastal wood fern (Dryopteris arguta)
Coast barrel cactus (Ferocactus viridescens)
Coast boykinia (Boykinia occidentalis)
Coast bush lupine (Lupinus arboreus)
Coast cholla (Cylindropuntia prolifera)
Coast goldenbush (Isocoma menziesii var. vernonioides)
Coast goosefoot (Chenopodium macrospermum)*
Coast live oak (Quercus agrifolia var. agrifolia)
Coast live oak, Southern (Quercus agrifolia var. oxyadenia)
Coast locoweed (Astragalus trichopodus var. lonchus)
Coast morning glory (Calystegia macrostegia ssp. cyclostegia)
Coast paintbrush (Castilleja affinis ssp. affinis)
Coast prickly-pear (Opuntia littoralis)
Coast range bindweed (Calystegia collina ssp. venusta)
Coast range melic (Melica imperfecta)
Coast range triteleia (Triteleia lugens)
Coast silktassel (Garrya elliptica)
Coastweed (Amblyopappus pusillus)
Cobweb thistle (Cirsium occidentale var. occidentale)
Cocklebur,
    [Common] (Xanthium strumarium)
    Spiny (Xanthium spinosum)
Coffeeberry,
    [Common] (Frangula californica ssp. californica)
    Hoary (Frangula californica ssp. tomentella)
    Sierra hoary (Frangula californica ssp. cuspidata)
Coffee fern (Pellaea andromedifolia)
Collar lupine (Lupinus truncatus)
Collinsia,
    Child's (Collinsia childii)
    Desert (Collinsia callosa)
    Parry's (Collinsia parryi)
    Small-flowered (Collinsia parviflora)
    Wright's (Collinsia torreyi var. wrightii)
Collomia,
    Large-flowered (Collomia grandiflora)
    Slenderleaf (Collomia linearis)
Colorado Desert larkspur (Delphinium parishii ssp. subglobosum)
Columbia cutleaf, see Southern mountain cutleaf
Columbine (Aquilegia formosa)
Comanche Point tidy tips (Layia leucopappa)
Comb-leaved threadplant (Nemacladus pinnatifidus)
Common beggar-ticks (Bidens pilosa)*
Common celery (Apium graveolens) *
Common chaffweed (Lysimachia minima)
Common deerweed (Acmispon glaber var. glaber)
Common eucrypta (Eucrypta chrysanthemifolia var. chrysanthemifolia)
Common fiddleneck (Amsinckia intermedia)
Common flax (Linum usitatissimum)*
Common goldfields (Lasthenia gracilis)
Common groundsel (Senecio vulgaris)*
Common gumplant (Grindelia camporum)
Common hillside daisy (Monolopia lanceolata)
Common horsetail (Equisetum arvense)
Common knotweed (Polygonum aviculare ssp. depressum)*
Common linanthus (Leptosiphon parviflorus)
Common madia (Madia elegans)
Common mallow (Malva neglecta)*
Common Mediterranean grass (Schismus barbatus)*
Common muilla (Muilla maritima)
Common oleander (Nerium oleander)*
Common phacelia (Phacelia distans)
Common reed (Phragmites australis)
Common scouring rush (Equisetum hyemale ssp. affine)
Common silverweed (Potentilla anserina ssp. anserina)
Common skullcap (Scutellaria tuberosa)
Common spikerush (Eleocharis macrostachya)
Common sun cup (Camissoniopsis bistorta)
Common sunflower (Helianthus annuus)
Common sweet-cicely (Osmorhiza brachypoda)
Common toad rush (Juncus bufonius var. bufonius)
Common tomato (Lycopersicon esculentum)*
Common wheat (Triticum aestivum)*
Common wild oats (Avena fatua)*
Condensed phlox (Phlox condensata)
Conejo buckwheat (Eriogonum crocatum)
Congdon's monkeyflower (Diplacus congdonii)
Congdon's phacelia (Phacelia congdonii)
Cooper's boxthorn (Lycium cooperi)
Cooper's broomrape (Aphyllon cooperi)
Cooper's dyssodia (Adenophyllum cooperi)
Cooper's goldenbush (Ericameria cooperi var. cooperi)
Cooper's goldflower (Hymenoxys cooperi)
Cooper's jewelflower (Caulanthus cooperi)
Cooper's lip fern (Myriopteris cooperae)
Cooper's rush (Juncus cooperi)
Cootamundra wattle (Acacia baileyana)*
Copperleaf, California (Acalypha californica)
Coralroot, Spotted (Corallorhiza maculata)
Cord grass (Spartina foliosa)
Coreopsis,
    Bigelow's (Leptosyne bigelovii)
    Giant (Leptosyne gigantea)
Corn chamomile (Anthemis arvensis)*
Corn lily (Veratrum californicum var. californicum)
Corn speedwell (Veronica arvensis)*
Corn spurrey (Spergula arvensis)*
Cotton-batting plant (Pseudognaphalium stramineum)
Cotton fern (Cheilanthes newberryi)
Cottonthorn,
    [Common] (Tetradymia comosa)
    Mojave (Tetradymia stenolepis)
Cottontop cactus (Echinocactus polycephalus var. polycephalus)
Cottonweed, Slender (Micropus californicus var. californicus)
Cottonwood,
    Black (Populus trichocarpa)
    Fremont's (Populus fremontii ssp. fremontii)
Cottony wild buckwheat (Eriogonum gossypinum)
Coues' senna (Senna covesii)
Coulter pine (Pinus coulteri)
Coulter's globemallow (Sphaeralcea coulteri)
Coulter's horseweed (Laennecia coulteri)
Coulter's jewelflower (Caulanthus coulteri)
Coulter's lupine (Lupinus sparsiflorus)
Coulter's lyrepod (Lyrocarpa coulteri)
Coulter's saltbush (Atriplex coulteri)
Coulter's spiderling (Boerhavia coulteri var. palmeri)
Coville's dwarf abronia (Abronia nana var. covillei)
Coville's fleabane (Erigeron breweri var. covillei)
Coville's lip fern (Myriopteris covillei)
Coville's purple mat (Nama demissa var. covillei)
Coville's rush (Juncus covillei)
Cow parsnip (Heracleum maximum)
Coyote brush (Baccharis pilularis ssp. consanguinea)
Coyote melon (Cucurbita palmata)
Coyote tobacco (Nicotiana attenuata)
Cream bush
    [Common] (Holodiscus discolor var. discolor)
    Small-leaved (Holodiscus discolor var. microphyllus)
Cream cups (Platystemon californicus)
Cream gilia (Leptosiphon chrysanthus ssp. decorus)
Creek clover (Trifolium obtusiflorum)
Creek monkeyflower (Erythranthe guttata)
Creeping grape holly (Berberis aquifolium var. repens)
Creeping sage (Salvia sonomensis)
Creeping snowberry (Symphoricarpos mollis)
Creeping wildrye (Elymus triticoides)
Creeping wood-sorrel (Oxalis corniculata)*
Creosote bush (Larrea tridentata)
Cress,
    Bitter (Cardamine oligosperma)
    Mouse-ear (Arabidopsis thaliana)*
    Wart (Lepidium didymum)*
    Winter (Barbarea orthoceras)
Crested milkvetch (Astragalus bicristatus)
Crested onion (Allium atrorubens var. cristatum)
Cretan mallow (Malva pseudolavatera)*
Crete weed (Hedypnois cretica)*
Crimson pitcher sage (Salvia spathacea)
Crimson spot rock-rose (Cistus ladanifer var. maculatus)*
Crinklemat,
    Fanleaf (Tiquilia plicata)
    Nuttall's (Tiquilia nuttallii)
    Palmer's (Tiquilia palmeri)
    Woody (Tiquilia canescens var. canescens)
Crossflower (Chorispora tenella)*
Crossosoma, Catalina (Crossosoma californicum)
Croton,
    California (Croton californicus)
    Wiggins's (Croton wigginsii)
Crownbeard,
    Big-leaved (Verbesina dissita)
    Golden (Verbesina encelioides ssp. exauriculata)
Crucifixion thorn (Castela emoryi)
Crum's monolopia (Monolopia stricta)
Cryptantha,
    Bearded (Cryptantha barbigera var. barbigera)
    Bownut (Oreocarya abortiva)
    Bush-loving (Cryptantha dumetorum)
    Bushy (Johnstonella racemosa)
    Cleveland's (Cryptantha clevelandii)
    Curvenut (Cryptantha recurvata)
    Cushion (Greeneocharis circumscissa var. circumscissa)
    Desert (Greeneocharis similis)
    Ferguson's bearded (Cryptantha barbigera var. fergusoniae)
    Gravel (Cryptantha decipiens)
    Guadalupe (Cryptantha maritima)
    Jones' cryptantha (Cryptantha muricata var. jonesii)
    Large-flowered (Cryptantha intermedia var. intermedia)
    Minute-flowered (Cryptantha micromeres)
    Mojave (Cryptantha mohavensis)
    Mountain red-root (Eremocarya lepida)
    Narrow-leaved (Johnstonella angustifolia)
    Nevada (Cryptantha nevadensis)
    New York Mountains (Oreocarya tumulosa)
    Pinewoods (Cryptantha simulans)
    Prickly-nut cryptantha (Cryptantha muricata var. denticulata)
    Red-root (Eremocarya micrantha var. micrantha)
    Ribbed (Johnstonella costata)
    Rigid (Cryptantha juniperensis)
    Roughseed (Oreocarya flavoculata)
    Scented (Cryptantha utahensis)
    Sharpnut (Cryptantha oxygona)
    Showy (Cryptantha muricata var. muricata)
    Slender (Cryptantha gracilis)
    Tejon (Cryptantha microstachys)
    Virgin River (Oreocarya virginensis)
    Winged (Johnstonella holoptera)
    Wingnut (Cryptantha pterocarya)
    Yellow (Oreocarya confertiflora)
Crystalline iceplant (Mesembryanthemum crystallinum)*
Cucumber, Wild (Marah macrocarpa)
Cudweed,
    Lowland (Gnaphalium palustre)
    Pink (Pseudognaphalium ramosissimum)
    Purple (Gamochaeta ustulata)
    Weedy (Pseudognaphalium luteoalbum)*
    Wright's (Pseudognaphalium canescens)
Cultivated four o'clock (Mirabilis jalapa var. jalapa)*
Cupleaf ceanothus (Ceanothus perplexans)
Curl-leaf mountain-mahogany (Cercocarpus ledifolius var. intermontanus)
Curly dock (Rumex crispus) *
Currant,
    Chaparral (Ribes malvaceum var. viridifolium)
    Evergreen (Ribes viburnifolium)
    Golden (Ribes aureum var. gracillimum)
    Mountain pink (Ribes nevadense)
    Wax (Ribes cereum var. cereum)
    White-flowering (Ribes indecorum)
Cursed crowfoot (Ranunculus sceleratus)
Curved sicklegrass (Parapholis incurva)*
Curved-stem phacelia (Phacelia curvipes)
Curvenut cryptantha (Cryptantha recurvata)
Curvenut pectocarya (Pectocarya recurvata)
Curvepod yellowcress (Rorippa curvisiliqua)
Cushenbury buckwheat (Eriogonum ovalifolium var. vineum)
Cushenbury milkvetch (Astragalus albens)
Cushenbury oxytheca (Acanthoscyphus parishii var. goodmaniana)
Cushion cryptantha (Greeneocharis circumscissa var. circumscissa)
Cutleaf, Columbia, see Southern mountain cutleaf
Cutleaf daisy (Erigeron compositus)
Cutleaf geranium (Geranium dissectum)*
Cut-leaf plantain (Plantago coronopus)*
Cuyamaca cypress (Hesperocyparis stephensonii)
Cuyama gilia (Gilia latiflora ssp. cuyamensis)
Cycladenia, Showy (Cycladenia humilis var. venusta)
Cymopterus, Gilman's (Cymopterus gilmanii)
Cypress,
    Cuyamaca (Hesperocyparis stephensonii)
    Tecate (Hesperocyparis forbesii)
Daisy,
    African (Dimorphotheca ecklonis)*
    Cutleaf (Erigeron compositus)
    English (Bellis perennis)*
    Ox-eye (Leucanthemum vulgare)*
    Panamint (Enceliopsis covillei)
    Rock (Perityle emoryi)
    Seaside (Erigeron glaucus)
    Silver Lake (Leucosyris arida)
    Woolly (Eriophyllum wallacei)
Daisy desertstar (Monoptilon bellidiforme)
Dalea,
    Downy (Dalea mollissima)
    Silky (Dalea mollis)
Dallis grass (Paspalum dilatatum)*
Dalmatian toadflax (Linaria dalmatica ssp. dalmatica)*
Dandelion,
    Annual mountain (Agoseris heterophylla var. heterophylla)
    California (Taraxacum californicum)
    [Common] (Taraxacum officinale)*
    Desert (Malacothrix glabrata)
    Mountain (Agoseris grandiflora var. grandiflora)
    Spearleaf mountain (Agoseris retrorsa)
Darnel (Festuca temulenta)*
Datura, Sacred (Datura wrightii)
Davidson's blue-eyed mary (Collinsia bartsiifolia var. davidsonii)
Davidson's buckwheat (Eriogonum davidsonii)
Davidson's bush mallow (Malacothamnus davidsonii)
Davidson's lotus (Acmispon nevadensis var. davidsonii)
Davidson's phacelia (Phacelia davidsonii)
Davidson's stonecrop (Sedum niveum)
Davis's pitted onion (Allium lacunosum var. davisiae)
Davy gilia (Gilia latiflora ssp. davyi)
Deane's wirelettuce (Stephanomeria exigua ssp. deanei)
Death camas (Toxicoscordion venenosum var. venenosum)
Death Valley blue-eyed grass (Sisyrinchium funereum)
Death Valley brown-eyed primrose (Chylismia claviformis ssp. funerea)
Death Valley monkeyflower (Diplacus rupicola)
Death Valley phacelia (Phacelia vallis-mortae)
Death Valley sage (Salvia funerea)
Decumbent gilia (Gila jacens)
Decumbent goldenbush (Isocoma menziesii var. decumbens)
Deerbrush (Ceanothus integerrimus var. macrothyrsus)
Deergrass (Muhlenbergia rigens)
Deerweed,
    Common (Acmispon glaber var. glaber)
    Island (Acmispon dendroideus var. dendroideus)
    San Miguel Island (Acmispon dendroideus var. veatchii)
    Short-winged (Acmispon glaber var. brevialatus)
    Silky (Acmispon procumbens var. procumbens)
Dehesa nolina (Nolina interrata)
Delicate buttercup (Ranunculus hebecarpus)
Del Mar manzanita (Arctostaphylos glandulosa ssp. crassifolia)
Deltoid balsamroot (Balsamorhiza deltoidea)
Dense false-gilia (Allophyllum gilioides ssp. gilioides)
Dense-flowered owl's clover (Castilleja densiflora ssp. gracilis)
Dense-flowered rein orchid (Piperia elongata)
Dense-fruited monkeyflower (Diplacus constrictus)
Dense sedge (Carex densa)
Desert agave (Agave deserti var. deserti)
Desert almond (Prunus fasciculata var. fasciculata)
Desert alyssum (Lepidium fremontii)
Desert apricot (Prunus fremontii)
Desert baccharis (Baccharis sergiloides)
Desert beardtongue (Penstemon fruticiformis var. fruticiformis)
Desert beauty (Linanthus bellus)
Desert bitterbrush (Purshia tridentata var. glandulosa)
Desert bluebells (Phacelia campanularia ssp. campanularia)
Desert brickellbush (Brickellia desertorum)
Desert calico (Loeseliastrum matthewsii)
Desert candle (Caulanthus inflatus)
Desert chicory (Rafinesquia neomexicana)
Desert collinsia (Collinsia callosa)
Desert crested wheat grass (Agropyron cristatum ssp. pectinatum)*
Desert cryptantha (Greeneocharis similis)
Desert dandelion (Malacothrix glabrata)
Desert dicoria (Dicoria canescens)
Desert dodder (Cuscuta denticulata)
Desert evening primrose (Oenothera californica ssp. avita)
Desert figwort (Scrophularia desertorum)
Desert-fir (Peucephyllum schottii)
Desert fivespot (Eremalche rotundifolia)
Desert germander (Teucrium glandulosum)
Desert globemallow (Sphaeralcea ambigua var. rugosa)
Desert gold poppy (Eschscholzia glyptosperma)
Desert gooseberry (Ribes velutinum)
Desert heron's bill (Erodium texanum)
Desert hoary-aster (Dieteria canescens var. leucanthemifolia)
Desert-holly (Atriplex hymenelytra)
Desert ironwood (Olneya tesota)
Desert larkspur (Delphinium parishii ssp. parishii)
Desert lavender (Condea emoryi)
Desert lily (Hesperocallis undulata)
Desert linanthus (Linanthus demissus)
Desert locust (Robinia neomexicana)
Desert lupine (Lupinus shockleyi)
Desert manzanita (Arctostaphylos parryana ssp. desertica)
Desert marigold (Baileya multiradiata)
Desert mariposa lily (Calochortus kennedyi var. munzii)
Desert milkweed (Ascelpias erosa)
Desert mistletoe (Phoradendron californicum)
Desert mousetail (Myosurus cupulatus)
Desert needlegrass (Stipa speciosa)
Desert olive (Forestiera pubescens)
Desert paintbrush (Castilleja chromosa)
Desert pale gilia (Aliciella hutchinsifolia)
Desert panic grass (Panicum urvilleanum)
Desert parsley (Lomatium mohavense)
Desert peach (Prunus andersonii)
Desert pennyroyal (Monardella exilis)
Desert penstemon (Penstemon pseudospectabilis)
Desert pincushion (Chaenactis stevioides)
Desert polygala (Rhinotropis acanthoclada)
Desert portulaca (Portulaca halimoides)
Desert pot-herb (Cistanthe ambigua)
Desert prickly-pear (Opuntia phaeacantha)
Desert rock-nettle (Eucnide urens)
Desert rock pea (Acmispon rigidus)
Desert sage (Salvia eremostachya)
Desert sand-verbena (Abronia villosa var. villosa)
Desert sandwort (Eremogone macradenia var. macradenia)
Desert scrub oak, see Tucker's oak
Desert senna (Senna armata)
Desert short-flowered threadplant (Nemacladus longiflorus var. breviflorus)
Desert spearleaf (Matelea parvifolia)
Desert spike-moss (Selaginella eremophila)
Desert spiny star (Coryphantha chlorantha)
Desert spurge, see Sonoran spurge
Desert star (Monoptilon bellioides)
Desert straw (Stephanomeria pauciflora)
Desert sunflower (Geraea canescens)
Desert sweet (Chamaebatiaria millefolium)
Desert thistle (Cirsium neomexicanum)
Desert thorn (Lycium brevipes var. brevipes)
Desert thornapple (Datura discolor)
Desert threadplant (Nemacladus rubescens)
Desert tobacco (Nicotiana obtusifolia)
Desert trumpet (Eriogonum inflatum)
Desert twining snapdragon (Antirrhinum filipes)
Desert unicorn-plant (Proboscidea althaeifolia)
Desert willow (Chilopsis linearis ssp. arcuata)
Desert windflower (Anemone tuberosa)
Desert wishbone bush (Mirabilis laevis var. villosa)
Desert woolstar (Eriastrum eremicum ssp. eremicum)
Desert zygadene (Zigadenus brevibracteatus)
Devil's thorn (Emex spinosa)*
Diamond-petalled clarkia (Clarkia rhomboidea)
Dicoria, Desert (Dicoria canescens)
Ditaxis
    Narrow-leaf (Ditaxis lanceolata)
    New Mexico (Ditaxis neomexicana)
Ditch beard grass (Polypogon interruptus)*
Diverse-leaved pondweed (Potamogeton diversifolius)
Dobiepod (Tropidocarpum gracile)
Dock,
    Curly (Rumex crispus)*
    Fiddle (Rumex pulcher)*
    Whorled (Rumex conglomeratus)*
    Willow-leaved (Rumex californicus)
Dodder,
    California (Cuscuta californica var. californica)
    Canyon (Cuscuta subinclusa)
    Desert (Cuscuta denticulata)
    Papillate (Cuscuta californica var. papillosa)
    Salt marsh (Cuscuta pacifica var. pacifica)
    Short-flowered California (Cuscuta occidentalis)
    Western field (Cuscuta campestris)
Dogbane, Spreading (Apocynum androsaemifolium)
Dogwood,
    American (Cornus sericea ssp. sericea)
    Mountain (Cornus nuttallii)
Dotted indigo bush (Psorothamnus polydenius)
Double-toothed sticky cinquefoil (Drymocallis glandulosa var. reflexa)
Doubtful penstemon (Penstemon Xdubius)
Douglas fir, Big-cone (Pseudotsuga macrocarpa)
Douglas phacelia (Phacelia douglasii)
Douglas's iris (Iris douglasiana)
Douglas's knotweed (Polygonum douglasii)
Douglas's microseris (Microseris douglasii ssp. douglasii)
Douglas's milkvetch (Astragalus douglasii var. douglasii)
Douglas's silver bush lupine (Lupinus albifrons var. douglasii)
Douglas's stitchwort (Sabulina douglasii)
Douglas's violet (Viola douglasii)
Dovefoot geranium (Geranium molle)*
Doveweed (Croton setiger)
Downingia, Spotted (Downingia bella)
Downy Chinese houses (Collinsia heterophylla var. austromontana)
Downy dalea (Dalea mollissima)
Downy monkeyflower (Mimetanthe pilosa)
Draba,
    Alkali (Cusickiella douglasii)
    California (Draba cuneifolia)
    Slender (Draba albertina)
    Southern California (Draba corrugata)
    Southern California rock (Draba saxosa)
    Spring (Draba verna)
Drew's silky lupine (Lupinus adsurgens)
Drummond's false pennyroyal (Hedeoma drummondii)
Duckweed, Turion (Lemna turionifera)
Dudleya,
    Agoura (Dudleya cymosa ssp. agourensis)
    Arizona chalk (Dudleya arizonica)
    Candleholder (Dudleya candelabrum)
    Canyon (Dudleya cymosa ssp. cymosa)
    Chalk (Dudleya pulverulenta)
    Greene's (Dudleya greenei)
    Hasse's (Dudleya virens ssp. hassei)
    Lanceleaf (Dudleya lanceolata)
    Low canyon (Dudleya cymosa ssp. pumila)
    Many-stemmed (Dudleya multicaulis)
    Orcutt's (Dudleya attenuata ssp. orcuttii)
    Rock (Dudleya saxosa ssp. aloides)
    San Bernardino Mountains (Dudleya abramsii ssp. affinis)
    San Gabriel Mountains (Dudleya densiflora)
    San Gabriel River (Dudleya cymosa ssp. crebrifolia)
    Santa Barbara Island (Dudleya traskiae)
    Sticky (Dudleya viscida)
    Variegated (Dudleya variegata)
Dudley's clarkia (Clarkia dudleyana)
Dune broom (Chaetadelpha wheeleri)
Dune buckwheat (Eriogonum deserticola)
Dunedelion (Malacothrix incana)
Dune grass, Eureka Valley (Swallenia alexandrae)
Dune lupine (Lupinus chamissonis)
Dune primrose, see Basket evening primrose
Dune spurge (Euphorbia ocellata ssp. arenicola)
Dune sunflower (Helianthus petiolaris ssp. canescens)
Dunn's lobelia (Lobelia dunnii var. serrata)
Dunn's mariposa lily (Calochortus dunnii)
Durango root (Datisca glomerata)
Dusty maidens (Chaenactis douglasii var. douglasii)
Dwarf abronia, Coville's (Abronia nana ssp. covillei)
Dwarf alpine paintbrush (Castilleja nana)
Dwarf athysanus (Athysanus pusillus)
Dwarf checkerbloom (Sidalcea malviflora ssp. dolosa)
Dwarf filago (Logfia depressa)
Dwarf four o'clock (Mirabilis albida)
Dwarf goldenbush (Ericameria nana)
Dwarf hawksbeard (Crepis nana)
Dwarf lewisia (Lewisia pygmaea)
Dwarf-mistletoe, Pine (Arceuthobium campylopodum)
Dwarf mountain ragwort (Senecio fremontii var. occidentalis)
Dwarf nettle (Urtica urens)*
Dwarf pearlwort (Sagina apetala)*
Dwarf three-petal bedstraw (Galium trifidum ssp. subbiflorum)
Dwarf white milkvetch (Astragalus didymocarpus var. dispermus)
Dwarf woollyheads (Psilocarphus brevissimus var. brevissimus)
Dyssodia,
    Cooper's (Adenophyllum cooperi)
    San Felipe (Adenophyllum porophylloides)
Ear drops, Golden (Dicentra chrysantha)
Early onion (Allium praecox)
Earth brodiaea (Brodiaea terrestris ssp. kernensis)
Eastern joshua tree (Yucca jaegeriana)
Eastern threadplant (Nemacladus orientalis)
East Mojave buckwheat (Eriogonum fasciculatum var. flavoviride)
Eastwood manzanita (Arctostaphylos glandulosa ssp. zacaensis)
Eastwood's baby blue eyes (Nemophila pulchella var. pulchella)
Eastwood's fiddleneck (Amsinckia eastwoodiae)
Eastwood's threadplant (Nemacladus eastwoodiae)
Edible fig (Ficus carica)*
Egg milkvetch (Astragalus oophorus var. oophorus)
Elderberry,
    Mexican (Sambucus mexicana)
    Red (Sambucus racemosa var. racemosa)
Elegant alumroot (Heuchera caespitosa)
Elegant clarkia (Clarkia unguiculata)
Elegant rock-cress, see California rock-cress
Elephant tree (Bursera microphylla)
Elk thistle (Cirsium scariosum var. scariosum)
Elmer's cinguefoil (Potentilla gracilis var. elmeri)
El Paso gilia (Gilia mexicana)
Emory baccharis, see Willow baccharis
Emory indigo bush (Psorothamnus emoryi)
Encelia,
    Acton (Encelia actoni)
    Green (Encelia virginensis)
    Rayless (Encelia frutescens)
Encinitas baccharis (Baccharis vanessae)
Engelmann oak (Quercus engelmannii)
Engelmann's hedgehog cactus (Echinocereus engelmannii)
English daisy (Bellis perennis)*
English ivy (Hedera helix)*
English plantain (Plantago lanceolata)*
Enigmatic bush mallow (Malacothamnus enigmaticus)
Entire-leaved thelypodium (Thelypodium integrifolium ssp. affine)
Ephedra,
    California (Ephedra californica)
    Green (Ephedra viridis)
    Nevada (Ephedra nevadensis)
Erect golden-aster (Heterotheca sessiliflora ssp. fastigiata)
Eschscholtz's buttercup (Ranunculus eschscholtzii var. oxynotus)
Esteve pincushion, see Desert pincushion
Estuary sea-blite (Suaeda esteroa)
Eucrypta,
    Common (Eucrypta chrysanthemifolia var. chrysanthemifolia)
    Small-flowered (Eucrypta micrantha)
    Torrey's (Eucrypta chrysanthemifolia var. bipinnatifida)
Eureka Dunes evening primrose (Oenothera avita ssp. eurekensis)
Eureka Valley dune grass (Swallenia alexandrae)
European yellow lupine (Lupinus luteus)*
Evening primrose,
    Basket evening primrose (Oenothera deltoides ssp. deltoides)
    Booth's clustered (Eremothera boothii ssp. condensata)
    Booth's desert (Eremothera boothii ssp. desertorum)
    Booth's intermediate (Eremothera boothii ssp. intermedia)
    Booth's shredding (Eremothera boothii ssp. decorticans)
    California (Oenothera californica ssp. californica)
    Cave (Oenothera cavernae)
    Desert (Oenothera californica ssp. avita)
    Eureka Dunes (Oenothera avita ssp. eurekensis)
    Hairy (Oenothera elata ssp. hirsutissima)
    Hooker's (Oenothera elata ssp. hookeri)
    Mexican (Oenothera speciosa)*
    Rose (Oenothera rosea)*
    Small (Camissoniopsis micrantha)
    Tufted (Oenothera cespitosa ssp. marginata)
Evening snow (Linanthus dichotomus)
Evergreen currant (Ribes viburnifolium)
Everlasting,
    California (Pseudognaphalium californicum)
    Feltleaf (Pseudognaphalium microcephalum)
    Fragrant (Pseudognaphalium beneolens)
    Slender (Pseudognaphalium thermale)
    Two-tone (Pseudognaphalium biolettii)
Everlasting neststraw (Stylocline gnaphaloides)
Ewan's cinquefoil (Drymocallis cuneifolia var. ewanii)
Eyed gilia (Gilia ophthalmoides)
Fagonia,
    Smooth-stemmed (Fagonia laevis)
    Sticky (Fagonia pachyacantha)
Fairy duster, Pink (Calliandra eriophylla)
Fairyfan, Gunsight (Clarkia xantiana)
Fairy lantern (Calochortus albus)
False-brome, Purple (Brachypodium distachyon)*
False-clover (Cleomella oxystyloides)
False-daisy (Eclipta prostrata)
False-indigo,
    California (Amorpha californica var. californica)
    Western (Amorpha fruticosa)
False-gilia,
    Dense (Allophyllum gilioides ssp. gilioides)
    Purple (Allophyllum divaricatum)
    Sticky (Allophyllum glutinosum)
    Violet (Allophyllum gilioides ssp. violaceum)
    White (Allophyllum integrifolium)
False-lupine,
    Silvery (Thermopsis californica var. argentata)
    Velvety (Thermopsis californica var. semota)
False solomon's seal,
    [Common] (Maianthemum racemosum)
    Star-flowered (Maianthemum stellatum)
False-spineflower (Hollisteria lanata)
Fan leaf (Psathyrotes annua)
Fanleaf crinklemat (Tiquilia plicata)
Fan palm, California (Washingtonia filifera)
Farewell-to-spring, see Punchbowl clarkia
Feltleaf everlasting (Pseudognaphalium microcephalum)
Fendlerbush, Utah (Fendlerella utahensis)
Fendler's bluegrass (Poa fendleriana ssp. longiligula)
Fendler's ground-cherry (Physalis hederifolia var. fendleri)
Fendler's meadow-rue (Thalictrum fendleri var. fendleri)
Fennel, Sweet (Foeniculum vulgare)*
Ferguson's bearded cryptantha (Cryptantha barbigera var. fergusoniae)
Fern,
    African asparagus (Asparagus asparagoides)*
    Bird's-foot (Pellaea mucronata var. mucronata)
    Bracken (Pteridium aquilinum var. pubescens)
    Brittle (Cystopteris fragilis)
    California cloak (Notholaena californica)
    California lace (Aspidotis californica)
    California maidenhair (Adiantum jordanii)
    Cliff sword (Polystichum imbricans ssp. curtum)
    Clover (Marsilea vestita ssp. vestita)
    Coastal silverback (Pentagramma viscosa)
    Coastal wood (Dryopteris arguta)
    Coffee (Pellaea andromedifolia)
    Cotton (Cheilanthes newberryi)
    Five-finger (Adiantum aleuticum)
    Giant chain (Woodwardia fimbriata)
    Goldback (Pentagramma triangularis ssp. triangularis)
    Jones' cloak (Argyrochosma jonesii)
    Lady (Athyrium filix-femina var. cyclosorum)
    Maidenhair (Adiantum capillus-veneris)
    Mountain holly (Polystichum scopulinum)
    Scaly cloak (Astrolepis cochisensis)
    Sonoran maiden fern (Pelazoneuron puberulum var. sonorensis)
    Western sword (Polystichum munitum)
Fernleaf ironwood (Lyonothamnus floribundus ssp. aspleniifolius)
Fernleaf lomatium (Lomatium multifidum)
Fescue,
    Rattail (Festuca myuros)*
    Red (Festuca rubra)
    Small (Festuca microstachys)
    Spike (Festuca kingii)
    Tall (Festuca arundinacea)*
Feverfew (Tanacetum parthenium)*
Few-flowered blue dicks (Dipterostemon capitatus ssp. pauciflorus)
Few-flowered caltrop (Kallstroemia parviflora)
Few-flowered heterocodon (Heterocodon rariflorum)
Few-flowered meadow-rue (Thalictrum sparsiflorum)
Few-flowered naked buckwheat (Eriogonum nudum var. pauciflorum)
Few-flowered woolstar (Eriastrum sparsiflorum)
Few-leaved checkerbloom (Sidalcea sparsifolia)
Fiddle dock (Rumex pulcher)*
Fiddleleaf, California (Nama californica)
Fiddleneck,
    Bristly (Amsinckia tessellata var. gloriosa)
    Checker (Amsinckia tessellata var. tessellata)
    Common (Amsinckia intermedia)
    Eastwood's (Amsinckia eastwoodiae)
    Rigid (Amsinckia retrorsa)
    Seaside (Amsinckia spectabilis var. spectabilis)
    Small-flowered (Amsinckia retrorsa)
Field hedge-parsley (Torilis arvensis)*
Field madder (Sherardia arvensis)*
Field mint (Mentha arvensis)*
Field mustard (Brassica rapa)*
Field willow-herb (Epilobium brachycarpum)
Fiesta flower,
    [Common] (Pholistoma auritum var. auritum)
    White (Pholistoma membranaceum)
Figwort,
    California (Scrophularia californica)
    Desert (Scrophularia desertorum)
Filago,
    California (Logfia filaginoides)
    Dwarf (Logfia depressa)
    Narrow-leaf (Logfia gallica)*
Filaree,
    Red-stem (Erodium cicutarium)*
    Short-fruited (Erodium brachycarpum)*
    White-flowered (California macrophylla)
    White-stem (Erodium moschatum)*
Fine-flower gilia (Gilia leptantha ssp. leptantha)
Fineleaf hymenopappus (Hymenopappus filifolius var. megacephalus)
Firecracker penstemon (Penstemon eatonii var. undosus)
Fire evax, see Stemless evax
Fire poppy (Papaver californicum)
Fireweed (Chamerion angustifolium ssp. circumvagum)
Fir, White (Abies concolor)
Fishhook cactus (Mammillaria tetrancistra)
Fish's milkwort (Rhinotropis cornuta var. fishiae)
Five-finger fern (Adiantum aleuticum)
Five-hook bassia (Bassia hyssopifolia)*
Five-needled thymophylla (Thymophylla pentachaeta var. belenidium)
Fivespot,
    [Common] (Nemophila maculata)
    Desert (Eremalche rotundifolia)
Five-tooth spineflower (Chorizanthe watsonii)
Flannel bush,
    [Common] (Fremontodendron californicum)
    Mexican (Fremontodendron mexicanum)
Flatcrown buckwheat (Eriogonum deflexum var. deflexum)
Flat-leaf summer-holly (Comarostaphylis diversifolia ssp. planifolia)
Flat sagebrush (Artemisia bigelovii)
Flat-topped broomrape (Aphyllon corymbosum)
Flat-topped buckwheat (Eriogonum plumatella)
Flax,
    Common (Linum usitatissimum)*
    Plains (Linum puberulum)
    Small-flowered dwarf (Hesperolinon micranthum)
    Western blue (Linum lewisii var. lewisii)
Flax-flowered linanthus (Leptosiphon liniflorus)
Flax-leaved monardella (Monardella linoides ssp. linoides)
Fleabane,
    Brewer's (Erigeron breweri var. breweri)
    Coville's (Erigeron breweri var. covillei)
    Mojave Brewer's (Erigeron breweri var. porphyreticus)
    Navajo (Erigeron concinnus)
    Parish's (Erigeron parishii)
    Pinzl's (Erigeron clokeyi var. pinzliae)
    Rayless (Erigeron aphanactis var. congestus)
    Rayless shaggy (Erigeron aphanactis var. aphanactis)
    Salt marsh (Pluchea odorata var. odorata)
    San Jacinto Mountains (Erigeron breweri var. jacinteus)
    Shortray (Erigeron lonchophyllus)
    Spreading (Erigeron divergens)
Flix weed (Descurainia sophia)*
Flowering quillwort (Triglochin scilloides)
Fluff grass (Dasyochloa pulchella)
Foothill clover, see Tree clover
Foothill lupine, see Arroyo lupine
Foothill needlegrass (Stipa lepida)
Foothill penstemon (Penstemon heterophyllus var. heterophyllus)   
Foothill shooting star (Primula hendersonii)
Forest camp sandwort (Eremogone macradenia var. arcuifolia)
Forest goosefoot (Chenopodium atrovirens)
Forest sedge (Carex multicaulis)
Fort Mojave buckwheat (Eriogonum ordii)
Fosberg's cholla (Cylindropuntia fosbergii)
Fountaingrass (Pennisetum setaceum)*
Four o'clock,
    Bigelow's desert (Mirabilis laevis var. villosa)
    Cultivated (Mirabilis jalapa var. jalapa)*
    Dwarf (Mirabilis albida)
    Giant (Mirabilis multiflora var. pubescens)
    Red (Mirabilis coccinea)
    Retrorse desert (Mirabilis laevis var. retrorsa)
    Slender-lobed (Mirabilis tenuiloba)
Four-leaf allseed (Polycarpon tetraphyllum ssp. tetraphyllum)*
Four-needle pinyon pine (Pinus quadrifolia)
Four-valved tobacco (Nicotiana quadrivalvis)
Four-wing saltbush (Atriplex canescens var. canescens)
Fowl mannagrass (Glyceria elata)
Foxglove (Digitalis purpurea)*
Foxtail barley (Hordeum murinum ssp. glaucum)*
Fragile-sheathed sedge (Carex fracta)
Fragrant everlasting (Pseudognaphalium beneolens)
Fragrant pitcher sage (Lepechinia fragrans)
Fragrant shooting star (Primula fragrans)
Fragrant snakeroot (Ageratina herbacea)
Fragrant snowberry (Symphoricarpos longiflorus)
Franciscan broomrape (Aphyllon franciscanum)
Frankenia, Palmer's (Frankenia palmeri)
Fremont's barberry (Berberis fremontii)
Fremont's bush mallow (Malacothamnus fremontii)
Fremont's cottonwood (Populus fremontii ssp. fremontii)
Fremont's goosefoot (Chenopodium fremontii)
Fremont's milkvetch (Astragalus lentiginosus var. fremontii)
Fremont's monkeyflower (Diplacus fremontii)
Fremont's phacelia (Phacelia fremontii)
Fremont's pincushion (Chaenactis fremontii)
Fremont's silktassel (Garrya fremontii)
Fremont's syntrichopappus (Syntrichopappus fremontii)
Fremont's thornbush (Lycium fremontii)
French broom (Genista monspessulana)*
Fringed amaranth (Amaranthus fimbriatus)
Fringed gentian, One-flowered, see Hiker's gentian
Fringed onion (Allium fimbriatum var. fimbriatum)
Fringed spineflower (Chorizanthe fimbriata var. fimbriata)
Fringe-pod (Thysanocarpus curvipes)
Fringe-pod, Santa Cruz Island (Thysanocarpus conchuliferus)
Fritillary,
    Ojai (Fritillaria ojaiensis)
    Pinewoods (Fritillaria pinetorum)
Frostmat (Achyronychia cooperi)
Fuchsia,
    California (Epilobium canum ssp. latifolium)
    Hoary (Epilobium canum ssp. canum)
Fuchsia-flowered gooseberry (Ribes speciosum)
Funnel bluebells (Phacelia campanularia ssp. vasiformis)
Gambel's dwarf milkvetch (Astragalus gambelianus)
Gander's cholla (Cylindropuntia ganderi)
Gaping goosefoot (Chenopodium hians)
Gaping penstemon (Keckiella breviflora var. breviflora)
Garden stock (Matthiola incana)*
Garland chrysanthemum (Glebionis coronaria)*
Gentian,
    Autumn dwarf (Gentianella amarella ssp. acuta)
    Catchfly (Eustoma exaltatum ssp. exaltatum)
    Hiker's (Gentianopsis simplex)
    Moss (Gentiana fremontii)
Geranium,
    California (Geranium californicum)
    Carolina (Geranium carolinianum)
    Cutleaf (Geranium dissectum)*
    Dovefoot (Geranium molle)*
    Roundleaf (Geranium rotundifolium)*
German-ivy, see Cape-ivy
Geyer's willow (Salix geyeriana)
Ghost flower (Antirrhinum confertiflorum)
Ghostly rubber rabbitbrush (Ericameria nauseosa ssp. hololeuca)
Giant blazing star (Mentzelia laevicaulis)
Giant chain fern (Woodwardia fimbriata)
Giant coreopsis (Leptosyne gigantea)
Giant four o'clock (Mirabilis multiflora var. pubescens)
Giant horsetail (Equisetum telmateia ssp. braunii)
Giant hyssop (Agastache urticifolia)
Giant reed (Arundo donax)*
Giant saguaro (Carnegiea gigantea)
Giant sequoia (Sequoiadendron giganteum)*
Giant Spanish needles (Palafoxia arida var. gigantea)
Giant stipa (Stipa coronata)
Giant wildrye (Elymus condensatus)
Giant woolstar (Eriastrum densifolium ssp. elongatum)
Gilia,
    Argus (Gilia brecciarum ssp. neglecta)
    Banded volcanic (Gilia ochroleuca ssp. bizonata)
    Bell (Linanthus campanulatus)
    Birdseye (Gilia tricolor ssp. diffusa)
    Bridges' (Navarretia leptalea ssp. bicolor)
    Broad-flowered (Gilia latiflora ssp. latiflora)
    Broad-leaf (Aliciella latifolia ssp. latifolia)
    Caraway-leaved (Saltugilia caruifolia)
    Chaparral (Gilia angelensis)
    Clokey's (Gilia clokeyi)
    Cream (Leptosiphon chrysanthus ssp. decorus)
    Cuyama (Gilia latiflora ssp. cuyamensis)
    Davy (Gilia latiflora ssp. davyi)
    Decumbent (Gilia jacens)
    Desert pale (Aliciella hutchinsifolia)
    El Paso (Gilia mexicana)
    Eyed (Gilia ophthalmoides)
    Fine-flower (Gilia leptantha ssp. leptantha)
    Globe (Gilia capitata ssp. abrotanifolia)
    Golden (Leptosiphon chrysanthus ssp. chrysanthus)
    Grant's, see Grant's woodland-gilia
    Great Basin (Aliciella leptomeria)
    Latimer's, see Latimer's woodland-gilia
    Little (Gilia minor)
    Miniature (Navarretia capillaris)
    Modoc (Gilia modocensis)
    Nevada (Gilia brecciarum ssp. brecciarum)
    Puff-calyx (Gilia aliquanta ssp. aliquanta)
    Purpus's (Gilia leptantha ssp. purpusii)
    Rock (Gilia scopulorum)
    Rosy (Gilia sinuata)
    San Bernardino showy (Gilia cana ssp. bernardina)
    Sand (Aliciella triodon)
    San Diego (Gilia diegensis
    San Gabriel Mountains (Gilia ochroleuca ssp. vivida)
    Showy (Gilia cana ssp. speciformis)
    Slender volcanic (Gilia ochroleuca ssp. exilis)
    Southern, see Southern woodland-gilia
    Splendid, see Splendid woodland-gilia
    Spreading (Ipomopsis polycladon)
    Star (Gilia stellata)
    Threadstem (Linanthus filiformis)
    Three-headed showy (Gilia cana ssp. triceps)
    Transmontane gilia (Gilia transmontana)
    Transverse fine-flower (Gilia leptantha ssp. transversa)
    Volcanic (Gilia ochroleuca ssp. ochroleuca)
    Western (Gilia aliquanta ssp. breviloba)
Gilman's buckwheat (Eriogonum gilmanii)
Gilman's cymopterus (Cymopterus gilmanii)
Gilman's milkvetch (Astragalus gilmanii)
Glandular showy penstemon (Penstemon spectabilis var. subviscosus)
Glandular threadplant (Nemacladus glanduliferus)
Glandular willow-herb (Epilobium ciliatum ssp. glandulosum)
Glasswort (Arthrocnemum subterminale)
Globe chamomile (Oncosiphon piluliferum)*
Globe gilia (Gilia capitata ssp. abrotanifolia)
Globemallow,
    Coulter's (Sphaeralcea coulteri)
    Desert (Sphaeralcea ambigua var. rugosa)
    Narrow-leaved (Sphaeralcea angustifolia)
Goldback fern
    [Common] (Pentagramma triangularis ssp. triangularis)
    Maxon's (Pentagramma maxonii)
Golden-aster,
    Bristly (Heterotheca sessiliflora ssp. echioides)
    Erect (Heterotheca sessiliflora ssp. fastigiata)
    Rough hairy (Heterotheca villosa var. scabra)
Golden bowl mariposa lily (Calochortus concolor)
Goldenbush,
    Boundary (Ericameria brachylepis)
    Bracted alkali (Isocoma acradenia var. bracteosa)
    Coast (Isocoma menziesii var. vernonioides)
    Cooper's (Ericameria cooperi var. cooperi)
    Decumbent (Isocoma menziesii var. decumbens)
    Dwarf (Ericameria nana)
    Interior (Ericameria linearifolia)
    Laguna Mountains (Ericameria cuneata var. macrocephala)
    Menzies' (Isocoma menziesii var. menziesii)
    Palmer's (Ericameria palmeri var. pachylepis)
    Parish's (Ericameria parishii var. parishii)
    Pine (Ericameria pinifolia)
    Prostrate coast (Isocoma menziesii var. sedoides)
    Rock (Ericameria cuneata var. cuneata)
    Sawtooth (Hazardia squarrosa var. grindelioides)
    Solitary-leaved alkali (Isocoma acradenia var. eremophila)
    Wide-leaved rock (Ericameria cuneata var. spathulata)
Golden chinch flower (Pectis papposa var. papposa)
Golden crownbeard (Verbesina encelioides ssp. exauriculata)
Golden currant (Ribes aureum var. gracillimum)
Golden eardrops (Ehrendorferia chrysantha)
Goldeneye,
    Mojave (Bahiopsis reticulata)
    Parish's (Bahiopsis parishii)
    San Diego County (Bahiopsis laciniata)
Golden-fleece (Ericameria arborescens)
Golden gilia (Leptosiphon chrysanthus ssp. chrysanthus)
Goldenheads,
    [Common] (Acamptopappus sphaerocephalus var. sphaerocephalus)
    Hairy (Acamptopappus sphaerocephalus var. hirtellus)
    Shockley's (Acamptopappus shockleyi)
Golden-rayed pentachaeta (Pentachaeta aurea ssp. aurea)
Goldenrod,
    California (Solidago velutina ssp. californica)
    Southern (Solidago confinis)
    Western (Euthamia occidentalis)
Golden sedge (Carex aurea)
Golden-spined cereus (Bergerocactus emoryi)
Golden stars (Bloomeria crocea var. crocea)
Goldentop grass (Lamarckia aurea)*
Golden wattle (Acacia longifolia)*
Goldenweed, Slender (Xanthisma gracile)
Golden yarrow (Eriophyllum confertiflorum var. confertiflorum)
Goldfields,
    California (Lasthenia californica ssp. californica)
    [Common] (Lasthenia gracilis)
    Rayless (Lasthenia glaberrima)
    Royal (Lasthenia coronaria)
Goldflower, Cooper's (Hymenoxys cooperi)
Goodding's black willow (Salix gooddingii)
Goodding's verbena (Verbena gooddingii)
Gooseberry,
    Bitter (Ribes amarum)
    Desert (Ribes velutinum)
    Fuchsia-flowered (Ribes speciosum)
    Hillside (Ribes californicum var. hesperium)
    Mountain (Ribes montigenum)
    Oak (Ribes quercetorum)
    Santa Cruz Island (Ribes thacherianum)
    Sierra (Ribes roezlii var. roezlii)
Goosefoot,
    Aridland (Chenopodium desiccatum)
    California (Chenopodium californicum)
    Coast (Chenopodium macrospermum)*
    Forest (Chenopodium atrovirens)
    Fremont's (Chenopodium fremontii)
    Gaping (Chenopodium hians)
    Jerusalem-oak (Dysphania botrys)*
    Meadow (Chenopodium pratericola)
    Nettleleaf (Chenopodium murale)*
    Pitseed (Chenopodium berlandieri)
Goosefoot bur-sage (Ambrosia chenopodiifolia)
Goosefoot violet (Viola purpurea ssp. purpurea)
Graceful bedstraw (Galium porrigens var. porrigens)
Graceful tarplant (Holocarpha virgata ssp. elongata)
Grama,
    Black (Bouteloua eriopoda)
    Blue (Bouteloua gracilis)
    Needle (Bouteloua aristidoides var. aristidoides)
    Red (Bouteloua trifida)
    Side-oats (Bouteloua curtipendula)
Grand hound's tongue (Adelinia grandis)
Grand juniper (Juniperus grandis)
Grant's carpet clover (Trifolium monanthum ssp. grantianum)
Grant's woodland-gilia (Saltugilia splendens ssp. grantii)
Grape soda lupine (Lupinus excubitus var. excubitus)
Grape, Wild (Vitis girdiana)
Grass,
    Bermuda (Cynodon dactylon)*
    Big galleta (Hilaria rigida)
    Blue-eyed (Sisyrinchium bellum)
    Common Mediterranean (Schismus barbatus)*
    Cord (Spartina foliosa)
    Dallis (Paspalum dilatatum)*
    Desert panic (Panicum urvilleanum)
    Ditch beard (Polypogon interruptus)*
    Goldentop (Lamarckia aurea)*
    Harding (Phalaris aquatica)*
    Kikuyu (Pennisetum clandestinum)*
    Knot (Paspalum distichum)
    Nit (Gastridium phleoides)*
    Rabbitsfoot grass (Polypogon monspeliensis)*
    Salt (Distichlis spicata)
    Shore (Distichlis littoralis)
    Smilo (Stipa miliacea)*
Grass-of-parnassus (Parnassia palustris)
Gravel cryptantha (Cryptantha decipiens)
Gravel ghost (Atrichoseris platyphylla)
Gravel milkvetch (Astragalus sabulonum)
Gray chickensage (Sphaeromeria cana)
Gray herniaria (Herniaria hirsuta var. cinerea)*
Grayleaf skullcap (Scutellaria siphocampyloides)
Gray-leaved violet (Violet pinetorum ssp. grisea)
Gray monardella (Monardella australis ssp. cinerea)
Gray pine (Pinus sabiniana)
Greasebush, Spiny (Glossopetalon spinescens var. aridum)
Greata's aster (Symphyotrichum greatae)
Great Basin gilia (Aliciella leptomeria)
Great Basin wildrye (Elymus cinereus)
Great red paintbrush (Castilleja miniata ssp. miniata)
Great valley phacelia (Phacelia ciliata)
Greenbark ceanothus (Ceanothus spinosus)
Green bentgrass (Polypogon viridis)*
Green encelia (Encelia virginensis)
Green ephedra (Ephedra viridis)
Greene's dudleya (Dudleya greenei)
Green-gentian,
    Parry's (Frasera parryi)
    Pine (Frasera neglecta)
Greenleaf manzanita (Arctostaphylos patula)
Green miner's lettuce (Claytonia parviflora ssp. viridis)
Green rabbitbrush (Ericameria teretifolia)
Grinnell's penstemon (Penstemon grinnellii var. grinnellii)
Ground-cherry,
    Fendler's (Physalis hederifolia var. fendleri)
    Lobed (Physalis lobata)
    Thick-leaved (Physalis crasssifolia)
Groundcone, California (Boschniakia strobilacea)
Ground ivy (Glechoma hederacea)*
Ground pink (Linanthus dianthiflorus)
Groundsel,
    Broom (Senecio spartioides)
    California (Senecio californicus)
    Common (Senecio vulgaris)*
    Mono (Senecio flaccidus var. monoensis)
Groundsmoke,
    Pinegrove (Gayophytum oligospermum)
    Small-flowered (Gayophytum diffusum ssp. parviflorum)
    Zig-zag (Gayophytum heterozygum)
Guadalupe cryptantha (Cryptantha maritima)
Guayule (Parthenium argentatum)*
Gum-leaved brickellbush (Brickellia longifolia var. multiflora)
Gumplant,
    Coastal (Grindelia stricta var. platyphylla)
    Common (Grindelia camporum)
    Hairy (Grindelia hirsutula)
    San Diego (Grindelia hallii)
Gunsight fairyfan (Clarkia xantiana ssp. xantiana)
Gypsum-loving larkspur (Delphinium gypsophilum)
Gypsum spring beauty (Claytonia gypsophiloides)
Hackberry, Western (Celtis reticulata)
Hairgrass, Slender (Deschampsia elongata)
Hairy blazing star (Mentzelia hirsutissima)
Hairy blue sage (Salvia dorrii var. pilosa)
Hairy bush monkeyflower (Diplacus longiflorus)
Hairy ceanothus (Ceanothus oliganthus var. oliganthus)
Hairy evening primrose (Oenothera elata ssp. hirsutissima)
Hairy goldenheads (Acamptopappus sphaerocephalus var. hirtellus)
Hairy gumplant (Grindelia hirsutula)
Hairy honeysuckle (Lonicera hispidula)
Hairy-leaved pectocarya (Pectocarya heterocarpa)
Hairy milkweed (Funastrum hirtellum)
Hairy owl's clover (Castilleja tenuis)
Hairypink (Petrorhagia dubia)*
Hairy-podded peppergrass (Lepidium lasiocarpum ssp. lasiocarpum)
Hairy sand-spurrey (Spergularia villosa)*
Hairy sun cup (Camissoniopsis hirtella)
Hairy windmills (Allionia incarnata var. villosa)
Hairy winter vetch (Vicia villosa ssp. villosa)*
Hairy wood rush (Luzula comosa)
Hairy yerba santa (Eriodictyon trichocalyx var. trichocalyx)
Hall's brome (Bromus hallii)
Hall's bush lupine (Lupinus albifrons var. hallii)
Hall's caulanthus (Caulanthus hallii)
Hall's tetracoccus (Tetracoccus hallii)
Hall's willow-herb (Epilobium hallianum)
Hansen's spike-moss (Selaginella hansenii)
Harding grass (Phalaris aquatica)*
Hare barley (Hordeum murinum ssp. leporinum)*
Hareleaf, Branched (Lagophylla ramosissima)
Harlequin lupine (Lupinus stiversii)
Harsh popcorn flower (Plagiobothrys hispidulus)
Hartweg's iris (Iris hartwegii ssp. australis)
Harvest brodiaea (Brodiaea elegans ssp. elegans)
Harwood's woolstar (Eriastrum harwoodii)
Hasse's dudleya (Dudleya virens ssp. hassei)
Hawksbeard,
    Dwarf (Crepis nana)
    Tall (Crepis acuminata)
    Western (Crepis occidentalis)
Hawkweed,
    [Common] (Hieracium argutum)
    Shaggy (Hieracium horridum)
    White-flowered (Hieracium albiflorum)
Hawkweed layia (Layia hieracioides)
Hazardia,
    Holly-leaved (Hazardia brickellioides)
    Island (Hazardia detonsa)
    Orcutt's (Hazardia orcuttii)
Heartleaf jewelflower (Streptanthus cordatus var. cordatus)
Heartleaf penstemon (Keckiella cordifolia)
Heartleaf pitcher sage (Lepechinia cardiophylla)
Heartleaf sun cup (Chylismia cardiophylla ssp. cardiophylla)
Heartleaf thornmint (Acanthomintha obovata ssp. cordata)
Heath,
    Alkali (Frankenia salina)
    Rose (Chaetopappa ericoides)
Heather,
    Mock (Ericameria ericoides)
    Mountain (Phyllodoce breweri)
Heckard's paintbrush (Castilleja montigena)
Hedge mustard (Sisymbrium officinale)*
Hedge-nettle,
    California (Stachys bullata)
    Rigid (Stachys rigida)
    White (Stachys albens)
Hedge-parsley,
    California (Yabea microcarpa)
    [Common] (Torilis nodosa)*
    Field (Torilis arvensis)*
Heermann's buckwheat (Eriogonum heermannii var. argense)
Heermann's buckwheat, Large (Eriogonum heermannii var. heermannii)
Heermann's lotus (Acmispon heermannii var. heermannii)
Heermann's tarplant (Holocarpha heermannii)
Heliotrope, Wild (Heliotropium curassavicum var. oculatum)
Hemlock, Poison (Conium maculatum)*
Hemp dogbane (Apocynum cannabinum)
Henbit (Lamium amplexicaule)*
Herb sophia, see Flix weed
Herniaria, Gray (Herniaria hirsuta var. cinerea)*
Heron's bill, Desert (Erodium texanum)
Hesperochiron, California (Hesperochiron nanus)
Heterocodon, Few-flowered (Heterocodon rariflorum)
Hibiscus, Rock (Hibiscus denudatus)
Hiddenflower phacelia (Phacelia cryptantha)
Hidden lake bluecurls (Trichostema austromontanum ssp. compactum)
Hikers' gentian (Gentianopsis simplex)
Hilend's bedstraw (Galium hilendiae ssp. hilendiae)
Hill lotus (Acmispon brachycarpus)
Hillside gooseberry (Ribes californicum var. hesperium)
Hillside woodland star (Lithophragma heterophyllum)
Himalaya-berry (Rubus armeniacus)*
Himalayan smartweed (Persicaria capitata)*
Hinds' narrowleaf willow (Salix exigua var. hindsiana)
Hoary-aster,
    [Common] (Dieteria canescens var. canescens)
    Desert (Dieteria canescens var. leucanthemifolia)
Hoary coffeeberry,
    [Common] (Frangula californica ssp. tomentella)
    Sierra (Frangula californica ssp. cuspidata)
Hoary fuchsia (Epilobium canum ssp. canum)
Hoaryleaf ceanothus (Ceanothus crassifolius var. crassifolius)
Hoary nettle (Urtica dioica ssp. holosericea)
Hoffmannseggia (Hoffmannseggia microphylla)
Hogbite (Chondrilla juncea)*
Hog fennel (Lomatium utriculatum)
Hog potato (Hoffmannseggia glauca)
Hole-in-the-sand plant (Nicolletia occidentalis)
Holly,
    Creeping grape (Berberis aquifolium var. repens)
    Desert- (Atriplex hymenelytra)
    Summer (Comarostaphylis diversifolia ssp. diversifolia)
    Summer (Comarostaphylis diversifolia ssp. planifolia)
Hollyleaf cherry (Prunus ilicifolia ssp. ilicifolia)
Hollyleaf navarretia (Navarretia atractyloides)
Hollyleaf redberry (Rhamnus ilicifolia)
Holly-leaved bursage (Ambrosia ilicifolia)
Holly-leaved hazardia (Hazardia brickellioides)
Holly-leaved tetracoccus (Tetracoccus ilicifolius)
Honey mesquite (Prosopis glandulosa var. torreyana)
Honeysuckle,
    Chaparral (Lonicera interrupta)
    Hairy (Lonicera hispidula)
    Southern (Lonicera subspicata var. denudata)
Honeysweet (Tidestromia suffruticosa var. oblongifolia)
Hooked navarretia (Navarettia hamata ssp. hamata)
Hooked popcorn flower (Plagiobothrys undulatus)
Hooker's evening primrose (Oenothera elata ssp. hookeri)
Hopsage, Spiny (Grayia spinosa)
Hop tree (Ptelea crenulata)
Horehound (Marrubium vulgare)*
Horkelia,
    Barton Flats (Horkelia wilderae)
    Cleveland's (Horkelia clevelandii var. clevelandii)
    Ramona (Horkelia truncata)
    Rydberg's (Horkelia rydbergii)
    Wedge-leaf (Horkelia cuneata var. cuneata)
    White Mountains (Horkelia hispidula)
Horsebrush,
    Longspine (Tetradymia axillaris var. longispina)
    Spineless (Tetradymia canescens)
    Striped (Tetradymia argyraea)
Horse-nettle, Silverleaf (Solanum elaeagnifolium)*
Horsetail,
    Common (Equisetum arvense)
    Giant (Equisetum telmateia ssp. braunii)
Horseweed,
    Coulter's (Laennecia coulteri)
    Small (Erigeron bonariensis)*
    Tall (Erigeron canadensis)
Hottentot fig (Carpobrotus edulis)*
Hound's tongue, Grand (Cynoglossum grande)
Hubby's phacelia (Phacelia cicutaria var. hubbyi)
Huckleberry, California (Vaccinum ovatum)
Hulsea,
    Alpine gold (Hulsea algida)
    Beautiful (Hulsea vestita ssp. callicarpha)
    Parry's (Hulsea vestita ssp. parryi)
    Pygmy (Hulsea vestita ssp. pygmaea)
    Red-rayed (Hulsea heterochroma)
    San Diego (Hulsea californica)
    San Gabriel Mountains (Hulsea vestita ssp. gabrielensis)
Humboldt lily (Lilium humboldtii ssp. ocellatum)
Hutchinsia, Prostrate (Hornungia procumbens)
Hymenoxys, Arizona (Tetraneuris acaulis var. arizonica)
Hyssop, Giant (Agastache urticifolia)
Hyssop loosestrife (Lythrum hyssopifolia)
Iceplant,
    Crystalline (Mesembryanthemum crystallinum)*
    Red (Malephora crocea)*
    Slender-leaved (Mesembryanthemum nodiflorum)*
Idaho bentgrass (Agrostis idahoensis)
Idaho blue-eyed grass (Sisyrinchium idahoense var. occidentale)
Imbricate phacelia (Phacelia imbricata var. patula)
Incense-cedar (Calocedrus decurrens)
Indian breadroot, see California breadroot
Indian clover, see Rancheria clover
Indian hemp, see Hemp dogbane
Indian mallow, see Palmer's mallow
Indian milkweed, see Woolly-fruited milkweed
Indian paintbrush,
    Desert, see Desert paintbrush
    Frosted, see Mount Gleason paintbrush
    Heckard's, see Heckard's paintbrush
    Lesser, see Lesser paintbrush
    Longleaf, see longleaf paintbrush
    Soft-leaved, see Softleaved paintbrush
    Woolly, see Woolly paintbrush
Indian ricegrass, see Sand ricegrass
Indian rushpea, see Hog potato
Indian springparsley, see Spring-parsley
Indian tobacco, see Four-valved tobacco
Indian warrior, see Warrior's plume
Indigo bush,
    California (Psorothamnus arborescens var. simplicifolius)
    Dotted (Psorothamnus polydenius)
    Emory (Psorothamnus emoryi)
    Little-leaved Mojave (Psorothamnus arborescens var. minutifolius)
    Schott's (Psorothamnus schottii)
Inflated cima milkvetch (Astragalus cimae var. sufflatus)
Inland scrub oak (Quercus berberidifolia)
Inland sticky cinquefoil (Drymocallis glandulosa var. glandulosa)
Interior goldenbush (Ericameria linearifolia)
Interior live oak,
    [Common] (Quercus wislizeni var. wislizeni)
    Shrubby (Quercus wislizeni var. frutescens)
Interior manzanita (Arctostaphylos parryana ssp. tumescens)
Interior rose (Rosa woodsii ssp. gratissima)
Intermediate mariposa lily (Calochortus weedii var. intermedius)
Intermediate sun cup (Camissoniopsis intermedia)
Intermediate wheat grass (Elymus hispidus)*
Inyo blazing star (Mentzelia oreophila)
Inyo frasera (Frasera puberulenta)
Iodine bush (Allenrolfea occidentalis)
Ipomopsis,
    Arizona (Ipomopsis arizonica)
    Ballhead (Ipomopsis congesta ssp. montana)
Iris,
    Douglas's (Iris douglasiana)
    Hartweg's (Iris hartwegii ssp. australis)
Iris-leaved rush (Juncus xiphioides)
Ironwood,
    Desert (Olneya tesota)
    Fernleaf (Lyonothamnus floribundus ssp. aspleniifolius)
    Santa Catalina Island (Lyonothamnus floribundus ssp. floribundus)
Island alumroot (Heuchera maxima)
Island buckwheat (Eriogonum grande var. grande)
Island bush monkeyflower (Diplacus parviflorus)
Island ceanothus (Ceanothus arboreus)
Island checkerbloom (Sidalcea malviflora ssp. malviflora)
Island deerweed (Acmispon dendroideus var. dendroideus)
Island hazardia (Hazardia detonsa)
Island leafy bedstraw (Galium angustifolium ssp. foliosum)
Island mallow (Malva assurgentiflora)
Island manzanita (Arctostaphylos insularis)
Island mountain-mahogany (Cercocarpus betuloides var. blancheae)
Island oak (Quercus tomentella)
Island paintbrush (Castilleja hololeuca)
Island redberry (Rhamnus pirifolia)
Island sagebrush (Artemisia nesiotica)
Island shooting star (Primula clevelandii ssp. insulare)
Island tarplant (Deinandra clementina)
Island wallflower (Erysimum insulare)
Italian ryegrass (Festuca perennis)*
Italian thistle (Carduus pycnocephalus ssp. pycnocephalus)*
Ithuriel's spear (Triteleia laxa)
Ives' phacelia (Phacelia ivesiana)
Ivesia,
    Mousetail (Ivesia santolinoides)
    Rock (Ivesia saxosa)
    Silver-haired (Ivesia argyrocoma var. argyrocoma)
    Tahquitz (Ivesia callida)
Ivy, English (Hedera helix)*
Jeffrey pine (Pinus jeffreyi)
Jepsonia, Parry's (Jepsonia parryi)
Jepson's bedstraw (Galium jepsonii)
Jepson's morning glory (Calystegia malacophylla ssp. pedicellata)
Jerusalem-oak goosefoot (Dysphania botrys)*
Jewelflower,
    Cooper's (Caulanthus cooperi)
    Coulter's (Caulanthus coulteri)
    Heartleaf (Streptanthus cordatus var. cordatus)
    Laguna Mountains (Streptanthus bernardinus)
    Payson's (Caulanthus simulans)
    Slender-pod (Caulanthus heterophyllus)
    Southern (Streptanthus campestris)
Jimsonweed (Datura stramonium)*
Johnny jump up (Viola pedunculata)
Johnson's bee-hive cactus (Sclerocactus johnsonii)
Johnston's bedstraw (Galium johnstonii)
Johnston's buckwheat (Eriogonum microtheca var. johnstonii)
Johnston's bush lupine (Lupinus albifrons var. johnstonii)
Johnston's monkeyflower (Diplacus johnstonii)
Jointed buckwheat (Eriogonum intrafractum)
Jointed goatgrass (Aegilops cylindrica)*
Jojoba (Simmondsia chinensis)
Jones' blazing star (Mentzelia jonesii)
Jones' cloak fern (Argyrochosma jonesii)
Jones' cryptantha (Cryptantha muricata var. jonesii)
Jones' linanthus (Linanthus jonesii)
Joshua tree
    Common (Yucca brevifolia)
    Eastern (Yucca jaegeriana)
July gold (Dedeckera eurekensis)
Jumping cholla (Cylindropuntia bigelovii)
Junegrass (Koeleria macrantha)
Juniper,
    California (Juniperus californica)
    Grand (Juniperus grandis)
    Utah (Juniperus osteosperma)
Juniper mistletoe (Phoradendron juniperinum)
Jurupa Hills sun cup (Camissoniopsis ignota)
Kallstroemia, California (Kallstroemia californica)
Keckiella,
    Northern blue-stemmed (Keckiella ternata var. septentrionalis)
    San Jacinto Mountains (Keckiella rothrockii var. jacintensis)
Kelloggia (Kelloggia galioides)
Kellogg's knotweed (Polygonum polygaloides ssp. kelloggii)
Kellogg's tarplant (Deinandra kelloggii)
Kelso Creek monkeyflower (Erythranthe shevockii)
Kennedy's buckwheat (Eriogonum kennedyi var. kennedyi)
Kentucky bluegrass (Poa pratensis ssp. pratensis)*
Kern larkspur (Delphinium hansenii ssp. kernense)
Kern mallow (Eremalche parryi ssp. kernensis)
Kern sun cup (Camissonia kernensis ssp. gilmanii)
Kern tarplant (Deinandra pallida)
Keysia (Glyptopleura marginata)
Kidneyleaf buckwheat (Eriogonum reniforme)
Kikuyu grass (Pennisetum clandestinum)*
King's bladderpod (Physaria kingii ssp. kingii)
King's sandwort (Eremogone kingii var. glabrescens)
Knapp's brickellbush (Brickellia knappiana)
Knapweed,
    Russian (Acroptilon repens)*
    Spotted (Centaurea stoebe ssp. micranthos)*
Knobcone pine (Pinus attenuata)
Knot grass (Paspalum distichum)
Knot-stemmed bastard sage (Eriogonum wrightii var. nodosum)
Knotty buckwheat, see knot-stemmed bastard-sage
Knotweed,
    Common (Polygonum aviculare ssp. depressum)*
    Douglas's (Polygonum douglasii)
    Kellogg's (Polygonum polygaloides ssp. kelloggii)
    Sawatch (Polygonum sawatchense ssp. sawatchense)
    Swamp (Persicaria amphibia)
Krantz's catchfly (Silene krantzii)
Lace fern, California (Aspidotis californica)
Lace-fringed spineflower (Chorizanthe fimbriata var. laciniata)
Lace-pod (Thysanocarpus laciniatus)
Ladder brake (Pteris vittata)*
Ladies' fingers (Dudleya edulis)
Lady fern (Athyrium filix-femina var. cyclosorum)
Laguna Mountains aster (Dieteria asteroides var. lagunensis)
Laguna Mountains goldenbush (Ericameria cuneata var. macrocephala)
Laguna Mountains jewelflower (Streptanthus bernardinus)
Lakeside ceanothus (Ceanothus cyaneus)
Lamb's quarters (Chenopodium album)*
Lanceleaf browneyes (Chylismia claviformis ssp. lancifolia)
Lanceleaf dudleya (Dudleya lanceolata)
Langloisia, Bristly (Langloisia setosissima ssp. setosissima)
La purisima manzanita (Arctostaphylos purissima)
Large-flower baby blue eyes (Nemophila menziesii var. menziesii)
Large-flowered collomia (Collomia grandiflora)
Large-flowered cryptantha (Cryptantha intermedia var. intermedia)
Large-flowered leptosiphon (Leptosiphon grandiflorus)
Large-flowered lotus (Acmispon grandiflorus var. grandiflorus)
Large-flowered phacelia (Phacelia grandiflora)
Large-flowered pincushion (Chaenactis macrantha)
Large Heermann's buckwheat (Eriogonum heermannii var. heermannii)
Large-leaved avens (Geum macrophyllum var. perincisum)
Large-nosed monkeyflower (Erythranthe nasuta)
Large yellow primrose (Oenothera primiveris)
Larkspur,
    Blue (Delphinium parryi ssp. parryi)
    Colorado Desert (Delphinium parishii ssp. subglobosum)
    Desert (Delphinium parishii ssp. parishii)
    Gypsum-loving (Delphinium gypsophilum)
    Kern (Delphinium hansenii ssp. kernense)
    Mountain (Delphinium glaucum)
    Mountain spreading (Delphinium patens ssp. montanum)
    Pale (Delphinium parishii ssp. pallidum)
    Scarlet (Delphinium cardinale)
    Spreading (Delphinium patens ssp. hepaticoideum)
Late-flowering mariposa lily (Calochortus fimbriatus)
Latimer's woodland-gilia (Saltugilia latimeri)
Laurel sumac (Malosma laurina)
Lavender, Desert (Hyptis emoryi)
Lavender windows (Phacelia exilis)
Lax flower (Baileya pauciradiata)
Layia, Hawkweed (Layia hieracioides)
Layne's locoweed (Astragalus layneae)
Leafstem tickseed (Leptosyne calliopsidea)
Leafy buckwheat (Eriogonum fasciculatum var. foliolosum)
Leafy daisy (Erigeron foliosus var. foliosus)
Least duckweed (Lemna minuta)
Leather root,
    [Common] (Hoita macrostachya)
    Roundleaf (Hoita orbicularis)
Leather spineflower (Lastarriaea coriacea)
Lemmon's catchfly (Silene lemmonii)
Lemmon's linanthus (Leptosiphon lemmonii)
Lemmon's mustard (Caulanthus anceps)
Lemmon's phacelia (Phacelia lemmonii)
Lemmon's willow (Salix lemmonii)
Lemonade berry (Rhus integrifolia)
Lemon lily (Lilium parryi)
Leopard lily (Lilium pardalinum)
Leptosiphon, Large-flowered (Leptosiphon grandiflorus)
Lesser mohavea (Antirrhinum mohavea)
Lesser paintbrush (Castilleja minor ssp. spiralis)
Lesser wintergreen (Pyrola minor)
Lessingia,
    Spring (Lessingia tenuis)
    Sticky (Lessingia glandulifera var. glandulifera)
    Warner Springs (Lessingia glandulifera var. tomentosa)
Lewisia,
    Dwarf (Lewisia pygmaea)
    Sierra (Lewisia nevadensis)
Lewis's sun cup (Camissonia lewisii)
Licorice, Wild (Glycyrrhiza lepidota)
Lilac sunbonnets (Langloisia setosissima ssp. punctata)
Lily,
    Chocolate (Fritillaria biflora var. biflora)
    Corn (Veratrum californicum var. californicum)
    Desert (Hesperocallis undulata)
    Humboldt (Lilium humboldtii ssp. ocellatum)
    Lemon (Lilium parryi)
    Leopard (Lilium pardalinum)
    Pink funnel (Muilla coronata)
    Star (Zigadenus fremontii)
    Striped adobe (Fritillaria striata)
Limber pine (Pinus flexilis)
Limestone beardtongue (Penstemon calcareus)
Limestone monkeyflower (Erythranthe calcicola)
Limestone phacelia (Phacelia affinis)
Linanthus,
    Baldwin Lake (Linanthus killipii)
    Bigelow's (Linanthus bigelovii ssp. johnsonii)
    Common (Leptosiphon parviflorus)
    Desert (Linanthus demissus)
    Flax-flowered (Leptosiphon liniflorus)
    Jones' (Linanthus jonesii)
    Lemmon's (Leptosiphon lemmonii)
    Little San Bernardino Mountains (Linanthus maculatus ssp. maculatus)
    Many-flowered (Leptosiphon floribundus ssp. floribundus)
    Mojave (Leptosiphon breviculus)
    Parry's (Linanthus parryae)
    Pygmy (Leptosiphon pygmaeus ssp. continentalis)
    San Gabriel (Linanthus concinnus)
    Santa Rosa Mountains (Leptosiphon floribundus ssp. hallii)
    Smooth many-flowered (Leptosiphon floribundus ssp. glaber)
Lindley's blazing star (Mentzelia lindleyi)
Lip fern,
    Cleveland's (Myriopteris clevelandii)
    Cooper's (Myriopteris cooperae)
    Coville's (Myriopteris covillei)
    Parry's (Myriopteris parryi)
    Slender (Myriopteris gracilis)
    Viscid (Myriopteris viscida)
    Wooton's (Myriopteris wootonii)
Little desert trumpet (Eriogonum trichopes)
Little elephant heads (Pedicularis attollens)
Little gilia (Gilia minor)
Little gold poppy (Eschscholzia minutiflora)
Littleleaf palo verde (Parkinsonia microphylla)
Littleleaf redberry (Rhamnus crocea)
Littleleaf rhatany (Krameria erecta)
Little-leaved brickellbush (Brickellia microphylla var. microphylla)
Little-leaved mock orange (Philadelphus microphyllus)
Little-leaved Mojave indigo bush (Psorothamnus arborescens var. minutifolius)
Little-leaved mountain-mahogany (Cercocarpus ledifolius var. intricatus)
Little-leaved yellow penstemon (Keckiella antirrhinoides var. microphylla)
Little monardella (Monardella nana)
Little prince's pine (Chimaphila menziesii)
Little San Bernardino Mountains linanthus (Linanthus maculatus ssp. maculatus)
Little spring beauty (Claytonia exigua ssp. exigua)
Little wiry sun cup (Camissonia pusilla)
Live oak,
    Canyon (Quercus chrysolepis)
    Coast (Quercus agrifolia var. agrifolia)
    Interior (Quercus wislizeni var. wislizeni)
    Shrubby interior (Quercus wislizeni var. frutescens)
    Southern coast (Quercus agrifolia var. oxyadenia)
Lobed ground-cherry (Physalis lobata)
Lobelia,
    Dunn's (Lobelia dunnii var. serrata)
    Scarlet (Lobelia cardinalis var. pseudosplendens)
Locoweed,
    Coast (Astragalus trichopodus var. lonchus)
    Layne's (Astragalus layneae)
    Narrowpod (Astragalus filipes)
    Pomona (Astragalus pomonensis)
    Whitney's (Astragalus whitneyi var. whitneyi)
Locust,
    Black (Robinia pseudoacacia)*
    Desert (Robinia neomexicana)
Lodgepole pine (Pinus contorta ssp. murrayana)
Lomatium,
    California (Lomatium californicum)
    Caraway-Leaved (Lomatium caruifolium var. caruifolium)
    Fernleaf (Lomatium multifidum)
    Nevada (Lomatium nevadense var. nevadense)
    Parish's (Lomatium nevadense var. parishii)
    Shiny (Lomatium lucidum)
    Woolly (Lomatium dasycarpum ssp. dasycarpum)
London rocket (Sisymbrium irio)*
Long-anthered rush (Juncus macrandrus)
Long-beaked storksbill (Erodium botrys)*
Longbeak streptanthella (Streptanthella longirostris)
Long-flowered threadplant (Nemacladus longiflorus var. longiflorus)
Longfruit sun cup (Eremothera chamaenerioides)
Longleaf paintbrush (Castilleja subinclusa ssp. subinclusa)
Longleaf plantain (Plantago elongata)
Long-leaved aster (Symphyotrichum ascendens)
Long-leaved rush (Juncus macrophyllus)
Longspine horsebrush (Tetradymia axillaris var. longispina)
Long-spurred lupine (Lupinus arbustus)
Long-spurred plectritis (Plectritis ciliosa)
Longstalk phacelia (Phacelia longipes)
Longstem buckwheat (Eriogonum elongatum var. elongatum)
Loosestrife,
    California (Lythrum californicum)
    Hyssop (Lythrum hyssopifolia)
Lotebush (Ziziphus parryi var. parryi)
Lotus,
    Broad-leaved (Hosackia crassifolia var. crassifolia)
    California (Acmispon wrangelianus)
    Coastal (Acmispon maritimus var. maritimus)
    Davidson's (Acmispon nevadensis var. davidsonii)
    Heermann's (Acmispon heermannii var. heermannii)
    Hill (Acmispon brachycarpus)
    Large-flowered (Acmispon grandiflorus var. grandiflorus)
    Pygmy (Acmispon haydonii)
    Scrub (Acmispon argyraeus var. multicaulis)
    Short-bannered coastal (Acmispon maritimus var. brevivexillus)
    Sierra Nevada (Acmispon nevadensis var. nevadensis)
    Silver (Acmispon argophyllus var. argophyllus)
    Small-flowered (Acmispon micranthus)
    Streambank (Hosackia oblongifolia var. oblongifolia)
    Strigose (Acmispon strigosus)
Lousewort, Pine (Pedicularis semibarbata)
Low bush monkeyflower (Diplacus aridus)
Low canyon dudleya (Dudleya cymosa ssp. pumila)
Lowland cudweed (Gnaphalium palustre)
Lowland purslane (Trianthema portulacastrum)
Low phacelia (Phacelia humilis var. dudleyi)
Low pussytoes (Antennaria dimorpha)
Lupine,
    Anderson's (Lupinus andersonii)
    Arizona (Lupinus arizonicus)
    Arroyo (Lupinus succulentus)
    Bajada (Lupinus concinnus)
    Bentham (Lupinus benthamii)
    Brewer's (Lupinus breweri var. breweri)
    Broad-leaved (Lupinus latifolius var. latifolius)
    Bush (Lupinus longifolius)
    Chick (Lupinus microcarpus var. horizontalis)
    Coast bush (Lupinus arboreus)
    Clustered tidy (Lupinus lepidus var. confertus)
    Collar (Lupinus truncatus)
    Coulter's (Lupinus sparsiflorus)
    Desert (Lupinus shockleyi)
    Douglas's silver bush (Lupinus albifrons var. douglasii)
    Drew's silky (Lupinus adsurgens)
    Dune (Lupinus chamissonis)
    European yellow (Lupinus luteus)*
    Grape soda (Lupinus excubitus var. excubitus)
    Hall's bush (Lupinus albifrons var. hallii)
    Harlequin (Lupinus stiversii)
    Johnston's bush (Lupinus albifrons var. johnstonii)
    Long-spurred (Lupinus arbustus)
    Matted (Lupinus breweri var. bryoides)
    Meadow (Lupinus polyphyllus var. burkei)
    Miniature (Lupinus bicolor)
    Pale yellow (Lupinus luteolus)
    Peirson's (Lupinus peirsonii)
    Royal desert (Lupinus odoratus)
    San Jacinto (Lupinus hyacinthinus)
    Sand (Lupinus brevicaulis)
    Showy Brewer's (Lupinus breweri var. grandiflorus)
    Silky (Lupinus elatus)
    Silver bush (Lupinus albifrons var. albifrons)
    Silvery (Lupinus argenteus var. argenteus)
    Sky (Lupinus nanus)
    Southern mountain (Lupinus albifrons var. austromontanus)
    Stinging (Lupinus hirsutissimus)
    Summer (Lupinus formosus var. formosus)
    Valley (Lupinus microcarpus var. microcarpus)
    White-whorled (Lupinus microcarpus var. densiflorus)
    Yellow-eyed (Lupinus flavoculatus)
Lyon's pentachaeta (Pentachaeta lyonii)
Lyrepod, Coulter's (Lyrocarpa coulteri)
Macloskie's violet (Viola macloskeyi)
Madia,
    Common (Madia elegans)
    Mountain (Madia glomerata)
    Pygmy (Hemizonella minima)
    Sticky (Madia gracilis)
    Threadstem (Madia exigua)
Madrone, Pacific (Arbutus menziesii)
Maidenhair fern,
    [Common] (Adiantum capillus-veneris)
    California (Adiantum jordanii)
Malacothrix,
    Annual (Malacothrix clevelandii)
    California (Malacothrix californica)
    Cliff (Malacothrix saxatilis var. implicata)
Malibu baccharis (Baccharis malibuensis)
Mallow,
    Alkali (Malvella leprosa)
    Apricot (Sphaeralcea ambigua var. ambigua)
    Bull (Malva nicaeensis)*
    Bush (Malacothamnus fasciculatus var. fasciculatus)
    Cretan (Malva pseudolavatera)*
    Indian Valley (Malacothamnus aboriginum)
    Island (Malva assurgentiflora)
    Many-flowered bush (Malacothamnus densiflorus)
    Newberry's velvet (Horsfordia newberryi)
    Palmer's (Abutilon palmeri)
    Rosy apricot (Sphaeralcea ambigua var. rosacea)
    Round-leaved bush (Malacothamnus orbiculatus)
    Rusby's desert (Sphaeralcea rusbyi var. eremicola)
    San Clemente Island bush (Malacothamnus clementinus)
    Shrubby mallow (Abutilon abutiloides)*
    White (Eremalche exilis)
Mannagrass, Fowl (Glyceria elata)
Man-root,
    California (Marah fabacea)
    Sierra (Marah horrida)
Many-flowered bahia (Picradeniopsis multiflora)
Many-flowered bush mallow (Malacothamnus densiflorus)
Many-flowered linanthus (Leptosiphon floribundus ssp. floribundus)
Many-flowered monkeyflower (Erythranthe floribunda)
Many-nerved catchfly (Silene multiflora)
Many-stemmed dudleya (Dudleya multicaulis)
Many-stem woolly sunflower (Eriophyllum multicaule)
Manzanita,
    Adams' (Arctostaphylos glandulosa ssp. adamsii)
    Big-berry (Arctostaphylos glauca)
    Del Mar (Arctostaphylos glandulosa ssp. crassifolia)
    Desert (Arctostaphylos parryana ssp. desertica)
    Eastwood (Arctostaphylos glandulosa ssp. zacaensis)
    Greenleaf (Arctostaphylos patula)
    Interior (Arctostaphylos parryana ssp. tumescens)
    Island (Arctostaphylos insularis)
    La purisima (Arctostaphylos purissima)
    McMinn's (Arctostaphylos viridissima)
    Mexican (Arctostaphylos pungens)
    Mission (Xylococcus bicolor)
    Otay (Arctostaphylos otayensis)
    Parry's (Arctostaphylos parryana ssp. parryana)
    Pink-bracted (Arctostaphylos pringlei ssp. drupacea)
    Rainbow (Arctostaphylos rainbowensis)
    San Gabriel (Arctostaphylos glandulosa ssp. gabrielensis)
    Santa Catalina Island (Arctostaphylos catalinae)
    Santa Monica Mountains, see Transverse Range
    Santa Rosa Island manzanita (Arctostaphylos confertiflora)
    Transverse Range (Arctostaphylos glandulosa ssp. mollis)
    Zaca Lake, see Eastwood (Arctostaphylos glandulosa ssp. zacaensis)
Marigold,
    Desert (Baileya multiradiata)
    Woolly (Baileya pleniradiata)
Marina,
    California (Marina orcuttii var. orcuttii)
    Parry's (Marina parryi)
Mariposa lily,
    Alkali (Calochortus striatus)
    Butterfly (Calochortus venustus)
    Catalina (Calochortus catalinae)
    Desert (Calochortus kennedyi var. munzii)
    Dunn's (Calochortus dunnii)
    Golden bowl (Calochortus concolor)
    Intermediate (Calochortus weedii var. intermedius)
    Late-flowering (Calochortus fimbriatus)
    Munz's (Calochortus palmeri var. munzii)
    Palmer's (Calochortus palmeri)
    Plain (Calochortus invenustus)
    Plummer's (Calochortus plummerae)
    Red (Calochortus kennedyi var. kennedyi)
    Slender (Calochortus clavatus var. gracilis)
    Splendid (Calochortus splendens)
    Weed's (Calochortus weedii var. weedii)
    Winding (Calochortus flexuosus)
    Yellow (Calochortus clavatus var. pallidus)
Mariposa rush (Juncus dubius)
Maroon-spotted woolstar (Eriastrum signatum)
Marsh bulrush (Bolboschoenus maritimus ssp. paludosus)
Marsh jaumea (Jaumea carnosa)
Martin's paintbrush (Castilleja applegatei ssp. martinii)
Mat cholla (Grusonia parishii)
Matchweed, California (Gutierrezia californica)
Matilija poppy,
    [Common] (Romneya coulteri)
    Bristly (Romneya trichocalyx)
Mat muhly (Muhlenbergia richardsonis)
Matted lupine (Lupinus breweri var. bryoides)
Maxon's goldback fern (Pentagramma maxonii)
Mayweed (Anthemis cotula)*
Mayweed, Valley (Matricaria occidentalis)
McMinn's manzanita (Arctostaphylos viridissima)
Meadow arnica (Arnica chamissonis)
Meadow barley (Hordeum brachyantherum ssp. californicum)
Meadowfoam, Parish's (Limnanthes alba ssp. parishii)
Meadow goosefoot (Chenopodium pratericola)
Meadow lupine (Lupinus polyphyllus var. burkei)
Meadow nemophila (Nemophila pedunculata)
Meadow-rue
    [Common] (Thalictrum fendleri var. polycarpum)
    Fendler's (Thalictrum fendleri var. fendleri)
    Few-flowered (Thalictrum sparsiflorum)
Meadow starwort (Stellaria longipes ssp. longipes)
Mecca-aster (Xylorhiza cognata)
Meconella, Small-flowered (Meconella denticulata)
Mediterranean broom (Genista linifolia)*
Mediterranean cabbage (Brassica fruticulosa)*
Melic, Coast range (Melica imperfecta)
Melica, Tall (Melica frutescens)
Melon, Coyote (Cucurbita palmata)
Menodora, Spiny (Menodora spinescens)
Menzies' campion (Silene menziesii)
Menzies' goldenbush (Isocoma menziesii var. menziesii)
Mesquite,
    Honey (Prosopis glandulosa var. torreyana)
    Screwbean (Prosopis pubescens)
Mexican aster (Cosmos bipinnatus)*
Mexican elderberry (Sambucus mexicana)
Mexican flannel bush (Fremontodendron mexicanum)
Mexican manzanita (Arctostaphylos pungens)
Mexican pink (Silene laciniata ssp. laciniata)
Mexican rush (Juncus mexicanus)
Mexican-tea (Dysphania ambrosioides)*
Microseris,
    Brown (Stebbinsoseris heterocarpa)
    Douglas's (Microseris douglasii ssp. douglasii)
Milkflower willow-herb (Epilobium lactiflorum)
Milkmaids (Cardamine californica)
Milk thistle (Silybum marianum)*
Milkvetch,
    Annual desert (Astragalus aridus)
    Bear Valley (Astragalus lentiginosus var. sierrae)
    Borrego (Astragalus lentiginosus var. borreganus)
    Broad-keeled (Astragalus platytropis)
    Cima (Astragalus cimae var. cimae)
    Crested (Astragalus bicristatus)
    Cushenbury (Astragalus albens)
    Douglas's (Astragalus douglasii var. douglasii)
    Dwarf white (Astragalus didymocarpus var. dispermus)
    Egg (Astragalus oophorus var. oophorus)
    Fremont's (Astragalus lentiginosus var. fremontii)
    Gambel's dwarf (Astragalus gambelianus)
    Gilman's (Astragalus gilmanii)
    Gravel (Astragalus sabulonum)
    Inflated cima (Astragalus cimae var. sufflatus)
    Minthorn's (Astragalus minthorniae var. villosus)
    Mojave (Astragalus mohavensis var. mohavensis)
    Naked (Astragalus serenoi var. shockleyi)
    Palmer's (Astragalus palmeri)
    Panamint (Astragalus panamintensis)
    Parish's (Astragalus douglasii var. parishii)
    Peirson's (Astragalus magdalenae var. peirsonii)
    Playa (Astragalus allochrous var. playanus)
    Preuss's (Astragalus preussii var. preussii)
    Providence Mountains (Astragalus nutans)
    Pursh's (Astragalus purshii var. lectulus)
    Salton (Astragalus crotalariae)
    San Luis Obispo (Astragalus curtipes)
    San Miguel (Astragalus miguelensis)
    Santa Barbara (Astragalus trichopodus var. phoxus)
    Scarlet (Astragalus coccineus)
    Shining (Astragalus lentiginosus var. micans)
    Thickpod (Astragalus pachypus)
    Tidestrom's (Astragalus tidestromii)
    Torrey's (Astragalus calycosus var. calycosus)
    Triple-ribbed (Astragalus tricarinatus)
    Two-seeded (Astragalus didymocarpus var. didymocarpus)
    Varied (Astragalus lentiginosus var. variabilis)
    Ventura marsh (Astragalus pycnostachyus var. lanosissimus)
    White Mountains (Astragalus lentiginosus var. semotus)
    Woollypod (Astragalus purshii var. tinctus)
Milkweed,
    California (Asclepias californica)
    Climbing (Funastrum cynanchoides var. hartwegii)
    Desert (Ascelpias erosa)
    Hairy (Funastrum hirtellum)
    Mojave (Asclepias nyctaginifolia)
    Narrow-leaved (Asclepias fascicularis)
    Rush (Asclepias subulata)
    White-stemmed (Asclepias albicans)
    Woolly (Asclepias vestita)
    Woolly-fruited (Asclepias eriocarpa)
Milkwort, Fish's (Rhinotropis cornuta var. fishiae)
Miners' lettuce,
    [Common] (Claytonia perfoliata ssp. perfoliata)
    Green (Claytonia parviflora ssp. viridis)
    Narrow-leaf (Claytonia parviflora ssp. parviflora)
    Southern (Claytonia perfoliata ssp. mexicana)
    Utah (Claytonia parviflora ssp. utahensis)
Miniature gilia (Navarretia capillaris)
Miniature lupine (Lupinus bicolor)
Miniature woolstar (Eriastrum diffusum)
Mint,
    Bergamot (Mentha Xpiperita var. citrata)*
    Mountain (Pycnanthemum californicum)
    Mustang (Monardella breweri ssp. lanceolata)
    Otay Mesa (Pogogyne nudiuscula)
Minthorn's milkvetch (Astragalus minthorniae var. villosus)
Mint-leaved vervain (Verbena menthifolia)
Minute-flowered cryptantha (Cryptantha micromeres)
Mission cactus (Opuntia ficus-indica)*
Mission manzanita (Xylococcus bicolor)
Mission woodland star (Lithophragma cymbalaria)
Mistletoe,
    Big-leaf (Phoradendron leucarpum ssp. macrophyllum)
    Bolle's (Phoradendron bolleanum)
    Desert (Phoradendron californicum)
    Juniper (Phoradendron juniperinum)
    Oak (Phoradendron leucarpum ssp. tomentosum)
    Pine dwarf (Arceuthobium campylopodum)
Mock heather (Ericameria ericoides)
Mock orange,
    Little-leaved (Philadelphus microphyllus)
    Wild (Philadelphus lewisii)
Mock-strawberry (Duchesnea indica var. indica)
Modoc gilia (Gilia modocensis)
Mohavea, Lesser (Antirrhinum mohavea)
Mojave-aster (Xylorhiza tortifolia var. tortifolia)
Mojave beardtongue (Penstemon clevelandii var. mohavensis)
Mojave Brewer's fleabane (Erigeron breweri var. porphyreticus)
Mojave brown-eyed primrose (Chylismia claviformis ssp. claviformis)
Mojave ceanothus (Ceanothus pauciflorus)
Mojave cottonthorn (Tetradymia stenolepis)
Mojave cryptantha (Cryptantha mohavensis)
Mojave desert plum (Prunus eremophila)
Mojave fishhook cactus (Sclerocactus polyancistrus)
Mojave goldeneye (Bahiopsis reticulata)
Mojave goosefoot violet (Viola purpurea ssp. mohavensis)
Mojave indigo bush, Little-leaved (Psorothamnus arborescens var. minutifolius)
Mojave linanthus (Leptosiphon breviculus)
Mojave milkvetch (Astragalus mohavensis var. mohavensis)
Mojave milkweed (Asclepias nyctaginifolia)
Mojave mound cactus (Echinocereus mojavensis)
Mojave owl's clover (Castilleja exserta ssp. venusta)
Mojave phacelia (Phacelia mohavensis)
Mojave popcorn flower (Simpsonanthus jonesii)
Mojave prickly poppy (Argemone corymbosa)
Mojave prickly-pear (Opuntia polyacantha var. erinacea)
Mojave ragwort (Senecio mohavensis)
Mojave rubber rabbitbrush (Ericameria nauseosa ssp. mohavensis)
Mojave sand-verbena (Abronia pogonantha)
Mojave spineflower (Chorizanthe spinosa)
Mojave spurge (Euphorbia schizoloba)
Mojave stinkweed (Cleomella obtusifolia)
Mojave sun cup (Camissonia campestris ssp. campestris)
Mojave tarplant (Deinandra mohavensis)
Mojave thistle (Cirsium mohavense)
Mojave woolstar (Eriastrum densifolium ssp. mohavense)
Mojave yucca (Yucca schidigera)
Monardella,
    Breweri (Monardella breweri ssp. breweri)
    Flax-leaved (Monardella linoides ssp. linoides)
    Gray (Monardella australis ssp. cinerea)
    Little (Monardella nana)
    Narrow-leaved (Monardella linoides ssp. erecta)
    Red (Monardella macrantha ssp. hallii)
    Southern (Monardella australis ssp. australis)
    Tehachapi (Monardella linoides ssp. oblonga)
    White-leaf (Monardella hypoleuca ssp. hypoleuca)
    Willowy (Monardella viminea)
Monkeyflower,
    Bent-stem (Erythranthe geniculata)
    Bigelow's (Diplacus bigelovii var. bigelovii)
    Bolander's (Diplacus bolanderi)
    Brewer's (Erythranthe breweri)
    Calico (Diplacus pictus)
    Cleveland's bush (Diplacus clevelandii)
    Congdon's (Diplacus congdonii)
    Creek (Erythranthe guttata)
    Death Valley (Diplacus rupicola)
    Dense-fruited (Diplacus constrictus)
    Downy (Mimetanthe pilosa)
    Fremont's (Diplacus fremontii)
    Hairy bush (Diplacus longiflorus)
    Island bush (Diplacus parviflorus)
    Johnston's (Diplacus johnstonii)
    Kelso Creek (Erythranthe shevockii)
    Large-nosed (Erythranthe nasuta)
    Limestone (Erythranthe calcicola)
    Low (Diplacus aridus)
    Many-flowered (Erythranthe floribunda)
    Musk (Erythranthe moschata)
    Northern desert (Diplacus bigelovii var. cuspidatus)
    Palmer's (Erythranthe palmeri)
    Parish's (Erythranthe parishii)
    Primrose (Erythranthe primuloides)
    Purple (Erythranthe purpurea)
    Red bush (Diplacus puniceus)
    Red Rock Canyon monkeyflower (Erythranthe rhodopetra)
    Red-stemmed (Erythranthe rubella)
    Rock-jasmine (Erythranthe androsacea)
    San Bernardino Mountains (Erythranthe exigua)
    Scarlet (Erythranthe cardinalis)
    Sierra Nevada (Erythranthe sierrae)
    Smallflower (Erythranthe inconspicua)
    Southern bush (Diplacus australis)
    Southern Sierra bush (Diplacus calycinus)
    Suksdorf's (Erythranthe suksdorfii)
    Tiling's (Erythranthe tilingii)
    Yellow (Diplacus brevipes)
Monkeyflower savory (Clinopodium mimuloides)
Mono groundsel (Senecio flaccidus var. monoensis)
Monolopia, Crum's (Monolopia stricta)
Moonwort, Scalloped (Botrychium crenulatum)
Mormon needlegrass (Stipa arida)
Morning glory,
    Beach (Calystegia soldanella)
    Coast (Calystegia macrostegia ssp. cyclostegia)
    Jepson's (Calystegia malacophylla ssp. pedicellata)
    Northern island (Calystegia macrostegia ssp. macrostegia)
    Peirson's (Calystegia peirsonii)
    Small-flowered (Convolvulus simulans)
    Southern California (Calystegia macrostegia ssp. arida)
    Southern island (Calystegia macrostegia ssp. amplissima)
    Western (Calystegia occidentalis ssp. fulcrata)
Mortonia (Mortonia utahensis)
Mosquito fern, Pacific (Azolla filiculoides)
Moss gentian (Gentiana fremontii)
Moss pygmyweed (Crassula tillaea)*
Moss rush (Juncus bryoides)
Mountain blazing star (Mentzelia montana)
Mountain blue penstemon (Penstemon laetus var. laetus)
Mountain brome (Bromus carinatus var. marginatus)
Mountain clarkia (Clarkia heterandra)
Mountain clover (Trifolium wormskioldii)
Mountain dandelion (Agoseris grandiflora var. grandiflora)
Mountain dogwood (Cornus nuttallii)
Mountain golden stars (Bloomeria crocea var. montana)
Mountain gooseberry (Ribes montigenum)
Mountain heather (Phyllodoce breweri)
Mountain holly fern (Polystichum scopulinum)
Mountain larkspur (Delphinium glaucum)
Mountain madia (Madia glomerata)
Mountain-mahogany,
    Birch-leaf (Cercocarpus betuloides var. betuloides)
    Catalina Island (Cercocarpus traskiae)
    Curl-leaf (Cercocarpus ledifolius var. intermontanus)
    Island (Cercocarpus betuloides var. blancheae)
    Little-leaved (Cercocarpus ledifolius var. intricatus)
    San Diego (Cercocarpus minutiflorus)
Mountain maple (Acer glabrum var. diffusum)
Mountain mint (Pycnanthemum californicum)
Mountain oxytrope (Oxytropis oreophila var. oreophila)
Mountain peppergrass (Lepidium montanum)
Mountain phacelia (Phacelia imbricata var. imbricata)
Mountain pink currant (Ribes nevadense)
Mountain prickly phlox (Linanthus pungens)
Mountain red-root cryptantha (Eremocarya lepida)
Mountain rock-cress (Boechera retrofracta X)
Mountain sagebrush (Artemisia tridentata ssp. vaseyana)
Mountain snowberry (Symphoricarpos rotundifolius var. parishii)
Mountain spreading larkspur (Delphinium patens ssp. montanum)
Mountain sweet-cicely (Osmorhiza berteroi)
Mountain tail leaf (Pericome caudata)
Mountain tansy mustard (Descurainia incisa ssp. incisa)
Mountain timothy (Phleum alpinum)
Mountain whitethorn (Ceanothus cordulatus)
Mountain wormwood (Artemisia ludoviciana ssp. incompta)
Mount Gleason paintbrush (Castilleja gleasoni)
Mount Laguna alumroot (Heuchera brevistaminea)
Mouse-ear chickweed (Cerastium glomeratum)*
Mouse-ear cress (Arabidopsis thaliana)*
Mousetail,
    Bristly (Myosurus apetalus var. montanus)
    Desert (Myosurus cupulatus)
Mousetail ivesia (Ivesia santolinoides)
Mt. Pinos onion (Allium howellii var. clokeyi)
Mud nama (Nama stenocarpa)
Mudwort, Stemless (Limosella acaulis)
Mugwort (Artemisia douglasiana)
Muhly,
    Bush (Muhlenbergia porteri)
    Mat (Muhlenbergia richardsonis)
    Pullup (Muhlenbergia filiformis)
Muilla,
    Cleveland's (Bloomeria clevelandii)
    Common (Muilla maritima)
Mulefat (Baccharis salicifolia ssp. salicifolia)
Mule's ears (Wyethia ovata)
Mullein,
    Wand (Verbascum virgatum)*
    Woolly (Verbascum thapsus)*
Muller's oak (Quercus cornelius-mulleri)
Munzothamnus, Blair's (Munzothamnus blairii)
Munz's buckwheat (Eriogonum umbellatum var. munzii)
Munz's cholla (Cylindropuntia munzii)
Munz's mariposa lily (Calochortus palmeri var. munzii)
Munz's sage (Salvia munzii)
Musk monkeyflower (Erythranthe moschata)
Mustang mint (Monardella breweri ssp. lanceolata)
Mustard,
    African (Strigosella africana)*
    Appressed-fruited mountain tansy (Descurainia incana)
    Black (Brassica nigra)*
    California (Caulanthus lasiophyllus)
    Field (Brassica rapa)*
    Hedge (Sisymbrium officinale)*
    Lemmon's (Caulanthus anceps)
    Mountain tansy (Descurainia incisa ssp. incisa)
    Oriental (Sisymbrium orientale)*
    Saharan (Brassica tournefortii)*
    Shortpod mustard (Hirschfeldia incana)
    Sierra tansy (Descurainia californica)
    Slender-petalled (Thelypodium stenopetalum)
    Tansy (Common) (Descurainia pinnata ssp. glabra)
    Tower (Turritis glabra)
    Tumble (Sisymbrium altissimum)*
    Western tansy (Descurainia pinnata ssp. brachycarpa)
Naked broomrape (Aphyllon purpureum)
Naked cleome (Cleomella sparsifolia)
Naked milkvetch (Astragalus serenoi var. shockleyi)
Naked-stem bedstraw (Galium angustifolium ssp. nudicaule)
Nama,
    Mud (Nama stenocarpa)
    Rothrock's (Nama rothrockii)
    Small-leaved (Nama pusillum)
Narrow-leaf ditaxis (Ditaxis lanceolata)
Narrow-leaf filago (Logfia gallica)*
Narrow-leaf miner's lettuce (Claytonia parviflora ssp. parviflora)
Narrowleaf stoneseed (Lithospermum incisum)
Narrow-leaf sun cup (Eremothera refracta)
Narrow-leaved bedstraw (Galium angustifolium ssp. angustifolium)
Narrow-leaved brickellbush (Brickellia oblongifolia var. linifolia)
Narrow-leaved cryptantha (Johnstonella angustifolia)
Narrow-leaved globemallow (Sphaeralcea angustifolia)
Narrow-leaved milkweed (Asclepias fascicularis)
Narrow-leaved monardella (Monardella linoides ssp. erecta)
Narrow-leaved onion (Allium amplectens)
Narrow-leaved paintbrush (Castilleja linariifolia)
Narrow-leaved stephanomeria (Stephanomeria tenuifolia)
Narrow-leaved stillingia (Stillingia linearifolia)
Narrow-leaved vetch (Vicia sativa ssp. nigra)
Narrow oatgrass (Trisetum spicatum)
Narrowpod locoweed (Astragalus filipes)
Navajo fleabane (Erigeron concinnus)
Navarretia,
    Baja (Navarretia peninsularis)
    Brewer's (Navarretia breweri)
    Hollyleaf (Navarretia atractyloides)
    Hooked (Navarettia hamata ssp. hamata)
    Ojai (Navarretia ojaiensis)
    Prostrate (Navarretia prostrata)
    Spreading (Navarretia fossalis)
Nealley three-awn (Aristida purpurea var. nealleyi)
Needle-and-thread (Stipa comata var. comata)
Needle grama (Bouteloua aristidoides var. aristidoides)
Needlegrass,
    Desert (Stipa speciosa)
    Foothill (Stipa lepida)
    Mormon (Stipa arida)
    Nodding (Stipa cernua)
    Parish's (Stipa parishii var. parishii)
    Purple (Stipa pulchra)
    San Diego County (Stipa diegoensis)
    Western (Stipa occidentalis ssp. occidentalis)
Needle spikerush (Eleocharis acicularis var. acicularis)
Nemophila, Meadow (Nemophila pedunculata)
Neststraw,
    Everlasting (Stylocline gnaphaloides)
    Woollyhead (Stylocline micropoides)
Nettle,
    Black hair (Hesperocnide tenella)
    California hedge- (Stachys bullata)
    Dwarf (Urtica urens)*
    Hoary (Urtica dioica ssp. holosericea)
    Rigid hedge- (Stachys ajugoides var. rigida)
Nettleleaf goosefoot (Chenopodium murale)*
Nevada blue-eyed grass (Sisyrinchium halophilum)
Nevada broomsage (Lepidospartum latisquamum)
Nevada buckwheat (Eriogonum umbellatum var. nevadense)
Nevada cinquefoil (Drymocallis lactea var. lactea)
Nevada cryptantha (Cryptantha nevadensis)
Nevada ephedra (Ephedra nevadensis)
Nevada gilia (Gilia brecciarum ssp. brecciarum)
Nevada goldeneye (Heliomeris multiflora var. nevadensis)
Nevada lomatium (Lomatium nevadense var. nevadense)
Nevada ninebark (Physocarpus alternans)
Nevada onion (Allium nevadense)
Nevada rock daisy (Laphamia megalocephala var. megalocephala)
Nevin's bird's beak (Cordylanthus nevinii)
Nevin's brickellbush (Brickellia nevinii)
Nevin's barberry (Berberis nevinii)
Nevin's woolly sunflower (Constancea nevinii)
Newberry's rattleweed (Astragalus newberryi var. newberryi)
Newberry's velvet-mallow (Horsfordia newberryi)
New Mexico ditaxis (Ditaxis neomexicana)
New York Mountains cryptantha (Oreocarya tumulosa)
New Zealand spinach (Tetragonia tetragonioides)*
Nightshade,
    Blue-witch nightshade (Solanum umbelliferum)
    Parish's (Solanum parishii)
    Purple (Solanum xanti)
    Small-flowered (Solanum americanum)
    White (Solanum douglasii)
Ninebark,
    Nevada (Physocarpus alternans)
    Pacific (Physocarpus capitatus)
Nit grass (Gastridium phleoides)*
Nodding bedstraw (Galium hallii)
Nodding needlegrass (Stipa cernua)
Nolina,
    Dehesa (Nolina interrata)
    Parry's (Nolina parryi)
Northern blue-stemmed keckiella (Keckiella ternata var. septentrionalis)
Northern Channel Islands phacelia (Phacelia insularis var. insularis)
Northern desert gilia, see transmontane gilia
Northern desert monkeyflower (Diplacus bigelovii var. cuspidatus)
Northern Grinnell's penstemon (Penstemon grinnellii var. scrophularioides)
Northern island morning glory (Calystegia macrostegia ssp. macrostegia)
Northern starwort (Stellaria calycantha)
Norwegian cinquefoil (Potentilla norvegica)*
Noseburn (Tragia ramosa)
Notchleaf phacelia (Phacelia crenulata var. ambigua)
Nuttall's crinklemat (Tiquilia nuttallii)
Nuttall's island bedstraw (Galium nuttallii ssp. insulare)
Nuttall's poverty weed (Monolepis nuttalliana)
Oak,
    Blue (Quercus douglasii)
    Brewer's (Quercus garryana var. breweri)
    California black (Quercus kelloggii)
    Canyon live (Quercus chrysolepis)
    Channel Island scrub (Quercus pacifica)
    Coast live (Quercus agrifolia var. agrifolia)
    Engelmann (Quercus engelmannii)
    Inland scrub (Quercus berberidifolia)
    Interior live (Quercus wislizeni var. wislizeni)
    Island (Quercus tomentella)
    Muller's (Quercus cornelius-mulleri)
    Oracle (Quercus Xmorehus)
    Palmer's (Quercus palmeri)
    San Gabriel Mountains leather (Quercus durata var. gabrielensis)
    Shrub live (Quercus turbinella)
    Shrubby interior live (Quercus wislizeni var. frutescens)
    Southern coast live (Quercus agrifolia var. oxyadenia)
    Tanbark (Notholithocarpus densiflorus)
    Torrey's scrub (Quercus acutidens)
    Tucker's (Quercus john-tuckeri)
    Valley (Quercus lobata)
Oak gooseberry (Ribes quercetorum)
Oak mistletoe (Phoradendron leucarpum ssp. tomentosum)
Oak violet (Viola purpurea ssp. quercetorum)
Oats,
    Common wild (Avena fatua)*
    Slender (Avena barbata)*
Ocotillo (Fouquieria splendens ssp. splendens)
Ojai fritillary (Fritillaria ojaiensis)
Ojai navarretia (Navarretia ojaiensis)
Oligomeris (Oligomeris linifolia)
Olive, Desert (Forestiera pubescens)
One-flowered fringed gentian, see Hiker's gentian
One-seeded pussypaws (Calyptridium monospermum)
One-sided bluegrass (Poa secunda ssp. secunda)
One-sided wintergreen (Orthilia secunda)
Onion,
    Burlew's (Allium burlewii)
    Crested (Allium atrorubens var. cristatum)
    Davis's pitted (Allium lacunosum var. davisiae)
    Early (Allium praecox)
    Fringed (Allium fimbriatum var. fimbriatum)
    Mt. Pinos (Allium howellii var. clokeyi)
    Narrow-leaved (Allium amplectens)
    Nevada (Allium nevadense)
    Parry's fringed (Allium parryi)
    Peninsular (Allium peninsulare var. peninsulare)
    Red-skinned (Allium haematochiton)
    San Bernardino mountain (Allium monticola)
    Sierra (Allium campanulatum)
Onionweed (Asphodelus fistulosus)*
Oracle oak (Quercus Xmorehus)
Orchard grass (Dactylis glomerata)*
Orchid,
    Alaska rein (Piperia unalascensis)
    Dense-flowered rein (Piperia elongata)
    Rein (Piperia cooperi)
    Royal rein (Piperia transversa)
    Stream (Epipactis gigantea)
    White-flowered bog (Platanthera dilatata var. leucostachys)
Orchid rock-rose (Cistus Xpurpureus)*
Orcutt's bird's beak (Dicranostegia orcuttiana)
Orcutt's brodiaea (Brodiaea orcuttii)
Orcutt's dudleya (Dudleya attenuata ssp. orcuttii)
Orcutt's hazardia (Hazardia orcuttii)
Orcutt's woody-aster (Xylorhiza orcuttii)
Orcutt's yellow pincushion (Chaenactis glabriuscula var. orcuttiana)
Oregon cliff fern (Woodsia oregana)
Oregon willow-herb (Epilobium oregonense)
Oriental mustard (Sisymbrium orientale)*
Oso berry (Oemleria cerasiformis)
Otay manzanita (Arctostaphylos otayensis)
Otay Mesa mint (Pogogyne nudiuscula)
Otay tarplant (Deinandra conjugens)
Oval-leaved buckwheat (Eriogonum ovalifolium var. ovalifolium)
Owl's clover,
    Dense-flowered (Castilleja densiflora ssp. gracilis)
    Hairy (Castilleja tenuis)
    Mojave (Castilleja exserta ssp. venusta)
    Purple (Castilleja exserta ssp. exserta)
    San Bernardino Mountains (Castilleja lasiorhyncha)
Oxalis, Wild (Oxalis californica)
Ox-eye daisy (Leucanthemum vulgare)*
Oxytheca,
    Chickweed (Sidotheca caryophylloides)
    Cushenbury (Acanthoscyphus parishii var. goodmaniana)
    Parish's (Acanthoscyphus parishii var. parishii)
    Roundleaf (Oxytheca perfoliata)
    Threelobe (Sidotheca trilobata)
    Whitemargin (Sidotheca emarginata)
Oxytrope, Mountain (Oxytropis oreophila var. oreophila)
Pacific blazing star (Mentzelia obscura)
Pacific madrone (Arbutus menziesii)
Pacific mosquito fern (Azolla filiculoides)
Pacific ninebark (Physocarpus capitatus)
Pacific pickleweed (Salicornia pacifica)
Pacific rush (Juncus effusus ssp. pacificus)
Pacific saltbush (Atriplex pacifica)
Pacific sanicle (Sanicula crassicaulis)
Pacific silverweed (Potentilla anserina ssp. pacifica)
Pacific wildrye (Elymus pacificus)
Paintbrush,
    Ashy-gray (Castilleja cinerea)
    Coast (Castilleja affinis ssp. affinis)
    Desert (Castilleja chromosa)
    Dwarf alpine (Castilleja nana)
    Mount Gleason (Castilleja gleasoni)
    Great red (Castilleja miniata)
    Heckard's (Castilleja montigena)
    Island (Castilleja hololeuca)
    Lesser (Castilleja minor ssp. spiralis)
    Longleaf (Castilleja subinclusa ssp. subinclusa)
    Martin's (Castilleja applegatei ssp. martinii)
    Narrow-leaved (Castilleja linariifolia)
    Soft-leaved (Castilleja mollis)
    Woolly (Castilleja foliolosa)
    Yellow (Castilleja plagiotoma)
Pale larkspur (Delphinium parishii ssp. pallidum)
Pale primrose (Camissoniopsis pallida ssp. pallida)
Pale yellow lupine (Lupinus luteolus)
Palmer's beadpod (Physaria tenella)
Palmer's buckwheat (Eriogonum palmerianum)
Palmer's catchfly (Silene bernardina)
Palmer's ceanothus (Ceanothus palmeri)
Palmer's crinklemat (Tiquilia palmeri)
Palmer's frankenia (Frankenia palmeri)
Palmer's goldenbush (Ericameria palmeri var. pachylepis)
Palmer's grappling hook (Harpagonella palmeri)
Palmer's mallow (Abutilon palmeri)
Palmer's mariposa lily (Calochortus palmeri var. palmeri)
Palmer's milkvetch (Astragalus palmeri)
Palmer's monkeyflower (Erythranthe palmeri)
Palmer's oak (Quercus palmeri)
Palmer's penstemon (Penstemon palmeri var. palmeri)
Palmer's sagewort (Artemisia palmeri)
Palmer's sun cup (Tetrapteron palmeri)
Palo verde
    [Common] (Parkinsonia florida)
    Littleleaf (Parkinsonia microphylla)
Pampas grass (Cortaderia selloana)*
Panamint buckwheat (Eriogonum panamintense)
Panamint butterfly bush (Buddleja utahensis)
Panamint daisy (Enceliopsis covillei)
Panamint milkvetch (Astragalus panamintensis)
Panamint phacelia (Phacelia perityloides var. perityloides)
Panamint prince's plume (Stanleya elata)
Pancake prickly pear (Opuntia chlorotica)
Panicled bulrush (Scirpus microcarpus)
Panicled pyrrocoma (Pyrrocoma racemosa var. paniculata)
Paperbag bush (Scutellaria mexicana)
Paperflower (Psilostrophe cooperi)
Papillate dodder (Cuscuta californica var. papillosa)
Parikh's threadplant (Nemacladus parikhiae)
Parish's bedstraw (Galium parishii)
Parish's bluecurls (Trichostema parishii)
Parish's broomrape (Aphyllon parishii ssp. parishii)
Parish's buckwheat (Eriogonum parishii)
Parish's catchfly (Silene parishii)
Parish's fleabane (Erigeron parishii)
Parish's goldenbush (Ericameria parishii var. parishii)
Parish's goldeneye (Bahiopsis parishii)
Parish's lomatium (Lomatium nevadense var. parishii)
Parish's lupine (Lupinus latifolius var. parishii)
Parish's meadowfoam (Limnanthes alba ssp. parishii)
Parish's milkvetch (Astragalus douglasii var. parishii)
Parish's monkeyflower (Erythranthe parishii)
Parish's needlegrass (Stipa parishii var. parishii)
Parish's nightshade (Solanum parishii)
Parish's oxytheca (Acanthoscyphus parishii var. parishii)
Parish's poppy (Eschscholzia parishii)
Parish's psoralea (Rupertia rigida)
Parish's rock-cress (Boechera parishii)
Parish's sagebrush (Artemisia tridentata ssp. parishii)
Parish's spurge (Euphorbia parishii)
Parish's tauschia (Tauschia parishii)
Parish's viguiera, see Parish's goldeneye
Parish's yampah,
    [Common] (Perideridia parishii ssp. parishii)
    Wide-leaved (Perideridia parishii ssp. latifolia)
Parry's collinsia (Collinsia parryi)
Parry's fringed onion (Allium parryi)
Parry's green-gentian (Frasera parryi)
Parry's hulsea (Hulsea vestita ssp. parryi)
Parry's jepsonia (Jepsonia parryi)
Parry's linanthus (Linanthus parryae)
Parry's lip fern (Myriopteris parryi)
Parry's manzanita (Arctostaphylos parryana ssp. parryana)
Parry's marina (Marina parryi)
Parry's nolina (Nolina parryi)
Parry's phacelia (Phacelia parryi)
Parry's pussypaws (Calyptridium parryi var. parryi)
Parry's rabbitbrush (Ericameria parryi var. aspera)
Parry's saltbush (Atriplex parryi)
Parry's spurge (Euphorbia parryi)
Parry's tetracoccus (Tetracoccus dioicus)
Parry's wild buckwheat (Eriogonum brachypodum)
Parry's wild parsley (Lomatium parryi)
Parry's wirelettuce (Stephanomeria parryi)
Parsley,
    Desert (Lomatium mohavense)
    Parry's wild (Lomatium parryi)
Patagonia plantain (Plantago patagonica)
Payson's jewelflower (Caulanthus simulans)
Pea,
    Chaparral (Pickeringia montana var. montana)
    Desert rock (Lotus rigidus)
    Woolly chaparral (Pickeringia montana var. tomentosa)
Peach, Desert (Prunus andersonii)
Peak rush-rose (Crocanthemum scoparium var. vulgare)
Pearlwort,
    Alpine (Sagina saginoides)
    Dwarf (Sagina apetala)*
    Western (Sagina decumbens ssp. occidentalis)
Pebble pincushion (Chaenactis carphoclinia var. carphoclinia)
Pectocarya,
    Bristly (Pectocarya setosa)
    Broad-fruited (Pectocarya platycarpa)
    Curvenut (Pectocarya recurvata)
    Hairy-leaved (Pectocarya heterocarpa)
    Slender (Pectocarya linearis ssp. ferocula)
    Winged (Pectocarya penicillata)
Pedicellate phacelia (Phacelia pedicellata)
Peirson's brown-eyed primrose (Chylismia claviformis ssp. peirsonii)
Peirson's lupine (Lupinus peirsonii)
Peirson's milkvetch (Astragalus magdalenae var. peirsonii)
Peirson's morning glory (Calystegia peirsonii)
Peirson's spring beauty (Claytonia peirsonii ssp. peirsonii)
Pellitory (Parietaria hespera var. hespera)
Pellitory, Pennsylvania (Parietaria pensylvanica)
Pencil cholla (Cylindropuntia ramosissima)
Peninsular onion (Allium peninsulare var. peninsulare)
Peninsular spineflower (Chorizanthe leptotheca)
Pennsylvania pellitory (Parietaria pensylvanica)
Pennyroyal,
    California false (Hedeoma nana ssp. californica)
    Desert (Monardella exilis)
    Rock (Monardella robisonii)
Penstemon,
    Beaked (Penstemon rostriflorus)
    Desert (Penstemon pseudospectabilis)
    Doubtful (Penstemon Xdubius)
    Firecracker (Penstemon eatonii var. undosus)
    Foothill (Penstemon heterophyllus var. heterophyllus)
    Gaping (Keckiella breviflora var. breviflora)
    Glandular showy (Penstemon spectabilis var. subviscosus)
    Grinnell's (Penstemon grinnellii var. grinnellii)
    Heartleaf (Keckiella cordifolia)
    Little-leaved yellow (Keckiella antirrhinoides var. microphylla)
    Mountain blue (Penstemon laetus var. laetus)
    Northern Grinnell's (Penstemon grinnellii var. scrophularioides)
    Palmer's (Penstemon palmeri var. palmeri)
    Royal (Penstemon speciosus)
    Smooth showy (Penstemon spectabilis var. spectabilis)
    Southern foothill (Penstemon heterophyllus var. australis)
    Thurber (Penstemon thurberi)
    Utah (Penstemon utahensis)
    Whorl-leaf (Keckiella ternata var. ternata)
    Yellow (Keckiella antirrhinoides var. antirrhinoides)
Pentachaeta,
    Golden-rayed (Pentachaeta aurea ssp. aurea)
    Lyon's (Pentachaeta lyonii)
    White-rayed pentachaeta (Pentachaeta aurea ssp. allenii)
Peony, Wild (Paeonia californica)
Pepper,
    Brazilian (Schinus terebinthifolius)*
    Peruvian (Schinus molle)*
Peppergrass,
    Hairy-podded (Lepidium lasiocarpum ssp. lasiocarpum)
    Mountain (Lepidium montanum)
    Perennial (Lepidium latifolium)*
    Shiny (Lepidium)
    Virginia (Lepidium virginicum ssp. virginicum)
    Wild (Lepidium virginicum ssp. menziesii)
    Yellow (Lepidium flavum)
Perennial chickweed (Cerastium fontanum ssp. vulgare)*
Perennial peppergrass (Lepidium latifolium)*
Perennial rock-cress (Boechera perennans)
Perennial sweet pea (Lathyrus latifolius)*
Periwinkle (Vinca major)*
Persian speedwell (Veronica persica)*
Peruvian pepper (Schinus molle)*
Petty spurge (Euphorbia peplus)*
Petunia, Seaside (Petunia parviflora)
Phacelia,
    Alkali (Phacelia neglecta)
    Aven Nelson's (Phacelia anelsonii)
    Branching (Phacelia ramosissima)
    Caltha-leaved (Phacelia calthifolia)
    Caterpillar (Phacelia cicutaria var. hispida)
    Changeable (Phacelia mutabilis)
    Charlotte's (Phacelia nashiana)
    Cleftleaf wild heliotrope (Phacelia crenulata var. crenulata)
    Common (Phacelia distans)
    Congdon's (Phacelia congdonii)
    Curved-stem (Phacelia curvipes)
    Davidson's (Phacelia davidsonii)
    Death Valley (Phacelia vallis-mortae)
    Douglas (Phacelia douglasii)
    Fremont's (Phacelia fremontii)
    Great valley (Phacelia ciliata)
    Hiddenflower (Phacelia cryptantha)
    Hubby's (Phacelia cicutaria var. hubbyi)
    Imbricate (Phacelia imbricata var. patula)
    Ives' (Phacelia ivesiana)
    Large-flowered (Phacelia grandiflora)
    Lemmon's (Phacelia lemmonii)
    Limestone (Phacelia affinis)
    Longstalk (Phacelia longipes)
    Low (Phacelia humilis var. dudleyi)
    Mojave (Phacelia mohavensis)
    Mountain (Phacelia imbricata var. imbricata)
    Northern Channel Islands (Phacelia insularis var. insularis)
    Notchleaf (Phacelia crenulata var. ambigua)
    Panamint (Phacelia perityloides var. perityloides)
    Parry's (Phacelia parryi)
    Rock (Phacelia egena)
    Round-leaved (Phacelia rotundifolia)
    Smallflower notchleaf (Phacelia crenulata var. minutiflora)
    Southern mountain (Phacelia austromontana)
    Sticky (Phacelia viscida var. viscida)
    Tansy-leaved (Phacelia tanacetifolia)
    Thick-leaved (Phacelia pachyphylla)
    Timberline (Phacelia hastata var. hastata)
    Two-color (Phacelia bicolor)
    White caterpillar (Phacelia cicutaria var. cicutaria)
    White sticky (Phacelia viscida var. albiflora)
    Yellow-throated (Phacelia brachyloba)
Phlox,
    Big Bear Valley (Phlox dolichantha)
    Common slender (Microsteris gracilis)
    Condensed (Phlox condensata)
    Prickly (Linanthus californicus)
    Mountain prickly (Linanthus pungens)
    San Jacinto prickly (Linanthus jaegeri)
    Southern mountain (Phlox austromontana)
    Spreading (Phlox diffusa)
    Stansbury (Phlox stansburyi ssp. stansburyi)
Phlox-leaved bedstraw (Galium andrewsii ssp. intermedium)
Pickleweed, Pacific (Salicornia pacifica)
Pigweed amaranth (Amaranthus albus)*
Pincushion,
    Desert (Chaenactis stevioides)
    Fremont's (Chaenactis fremontii)
    Large-flowered (Chaenactis macrantha)
    Orcutt's yellow (Chaenactis glabriuscula var. orcuttiana)
    Pebble (Chaenactis carphoclinia var. carphoclinia)
    Santolina (Chaenactis santolinoides)
    White (Chaenactis artemisiifolia)
    Xantus (Chaenactis xantiana)
    Yellow (Chaenactis glabriuscula var. glabriuscula)
Pine,
    Aleppo (Pinus halapensis)*
    Bishop (Pinus muricata)
    Bristlecone (Pinus longaeva)
    Coulter (Pinus coulteri)
    Four-needle pinyon (Pinus quadrifolia)
    Gray (Pinus sabiniana)
    Jeffrey (Pinus jeffreyi)
    Knobcone (Pinus attenuata)
    Limber (Pinus flexilis)
    Lodgepole (Pinus contorta ssp. murrayana)
    Singleleaf pinyon (Pinus monophylla)
    Sugar (Pinus lambertiana)
    Torrey (Pinus torreyana ssp. torreyana)
    Yellow (Pinus ponderosa var. pacifica)
Pineapple cactus, see Johnson's bee-hive cactus
Pineapple weed (Matricaria discoidea)*
Pinedrops (Pterospora andromedea)
Pine dwarf mistletoe (Arceuthobium campylopodum)
Pine goldenbush (Ericameria pinifolia)
Pine green-gentian (Frasera neglecta)
Pinegrove groundsmoke (Gayophytum oligospermum)
Pineland buckwheat (Eriogonum molestum)
Pine lousewort (Pedicularis semibarbata)
Pine violet (Viola pinetorum ssp. pinetorum)
Pinewoods cryptantha (Cryptantha simulans)
Pinewoods fritillary (Fritillaria pinetorum)
Pink,
    California (Silene laciniata ssp. californica)
    Ground (Linanthus dianthiflorus)
    Mexican (Silene laciniata ssp. laciniata)
    Windmill (Silene gallica)*
Pink alumroot (Heuchera rubescens)
Pink-bracted manzanita (Arctostaphylos pringlei ssp. drupacea)
Pink cudweed (Pseudognaphalium ramosissimum)
Pink fairy duster (Calliandra eriophylla)
Pink funnel lily (Muilla coronata)
Pink rock-rose (Cistus incanus)*
Pink sand-verbena (Abronia umbellata var. umbellata)
Pink spineflower (Chorizanthe membranacea)
Pink velvet-mallow (Horsfordia alata)
Pin-point clover (Trifolium gracilentum)
Pinzl's fleabane (Erigeron clokeyi var. pinzliae)
Pipestems (Clematis lasiantha)
Pipsissewa (Chimaphila umbellata)
Pitcher sage,
    Crimson (Salvia spathacea)
    Fragrant (Lepechinia fragrans)
    Heartleaf (Lepechinia cardiophylla)
Pitch trefoil (Bituminaria bituminosa)*
Pitseed goosefoot (Chenopodium berlandieri)
Plain mariposa lily (Calochortus invenustus)
Plains flax (Linum puberulum)
Plantain,
    Broad-leaf (Plantago major)
    California (Plantago erecta)
    Cut-leaf (Plantago coronopus)*
    English (Plantago lanceolata)*
    Longleaf (Plantago elongata)
    Patagonia (Plantago patagonica)
    Sand (Plantago arenaria)*
    Water (Alisma triviale)
    Woolly (Plantago ovata var fastigiata)
Playa milkvetch (Astragalus allochrous var. playanus)
Plectritis, Long-spurred (Plectritis ciliosa)
Plume acacia (Paraserianthes lophantha)*
Plummer's baccharis (Baccharis plummerae ssp. plummerae)
Plummer's mariposa lily (Calochortus plummerae)
Poison hemlock (Conium maculatum)*
Poison oak, Western (Toxicodendron diversilobum)
Poison sanicle (Sanicula bipinnata)
Pokeweed (Phytolacca americana)*
Polished blazing star (Mentzelia polita)
Polypody,
    California (Polypodium californicum)
    Western (Polypodium hesperium)
Pomona locoweed (Astragalus pomonensis)
Pondweed, Diverse-leaved (Potamogeton diversifolius)
Poodle-dog bush (Eriodictyon parryi)
Poor man's timothy (Iva hayesiana)
Popcorn flower,
    Adobe (Plagiobothrys acanthocarpus)
    Arizona (Plagiobothrys arizonicus)
    California (Plagiobothrys collinus var. fulvescens)
    Harsh (Plagiobothrys hispidulus)
    Hooked (Plagiobothrys undulatus)
    Mojave (Simpsonanthus jonesii)
    Rusty-haired (Plagiobothrys nothofulvus)
    Slender (Plagiobothrys tenellus)
    Tawny (Plagiobothrys fulvus var. campestris)
    Valley (Plagiobothrys canescens var. canescens)
Poppy,
    Bear (Arctomecon merriamii)
    Bush (Dendromecon rigida)
    California (Eschscholzia californica)
    Channel Island tree (Dendromecon harfordii)
    Desert gold (Eschscholzia glyptosperma)
    Fire (Papaver californicum)
    Little gold (Eschscholzia minutiflora)
    Matilija (Romneya coulteri)
    Mojave prickly (Argemone corymbosa)
    Parish's (Eschscholzia parishii)
    Pygmy (Canbya candida)
    Tejon (Eschscholzia lemmonii ssp. kernensis)
    Tufted (Eschscholzia caespitosa)
    Wind (Papaver heterophyllum)
Poreleaf, Slender (Porophyllum gracile)
Portuguese broom (Cytisus striatus)*
Portulaca, Desert (Portulaca halimoides)
Poverty weed,
    [Common] (Iva axillaris)
    Nuttall's (Monolepis nuttalliana)
Pretty face (Triteleia ixioides ssp. scabra)
Preuss's milkvetch (Astragalus preussii var. preussii)
Prickleleaf, Shockley's (Hecastocleis shockleyi)
Pricklepoppy, Mojave (Argemone corymbosa)
Prickly lettuce (Lactuca serriola)*
Prickly-nut cryptantha (Cryptantha muricata var. denticulata)
Prickly-pear,
    Chaparral (Opuntia oricola)
    Coast (Opuntia littoralis)
    Desert (Opuntia phaeacantha)
    Mojave (Opuntia polyacantha var. erinacea)
    Pancake (Opuntia chlorotica)
    Vasey's (Opuntia vaseyi)
Prickly phlox,
    [Common] (Linanthus californicus)
    Mountain (Linanthus pungens)
    San Jacinto (Linanthus jaegeri)
Prickly sow-thistle (Sonchus asper ssp. asper)*
Pride of the mountains (Penstemon newberryi var. newberryi)
Primrose,
    Basket evening (Oenothera deltoides ssp. deltoides)
    Beach (Camissonia cheiranthifolia ssp. suffruticosa)
    California evening (Oenothera californica ssp. californica)
    Channel Islands beach (Camissonia cheiranthifolia ssp. cheiranthifolia)
    Death Valley brown-eyed (Camissonia claviformis ssp. funerea)
    Desert evening (Oenothera californica ssp. avita)
    Eureka Dunes evening (Oenothera californica ssp. eurekensis)
    Hairy evening (Oenothera elata ssp. hirsutissima)
    Hooker's evening (Oenothera elata ssp. hookeri)
    Large yellow (Oenothera primiveris)
    Mojave brown-eyed (Camissonia claviformis ssp. claviformis)
    Mustard evening (Camissonia californica)
    Pale (Camissoniopsis pallida ssp. pallida)
    Peirson's brown-eyed (Camissonia claviformis ssp. peirsonii)
    Rose evening (Oenothera rosea)*
    Small evening (Camissonia micrantha)
    Spike (Epilobium densiflorum)
    Tufted evening (Oenothera caespitosa ssp. marginata)
Primrose monkeyflower (Erythranthe primuloides)
Prince's pine, Little (Chimaphila menziesii)
Prince's plume,
    [Common] (Stanleya pinnata var. pinnata)
    Panamint (Stanleya elata)
Pringle's woolly sunflower (Eriophyllum pringlei)
Prostrate coast goldenbush (Isocoma menziesii var. sedoides)
Prostrate hutchinsia (Hornungia procumbens)
Prostrate navarretia (Navarretia prostrata)
Prostrate spineflower (Chorizanthe procumbens)
Prostrate spurge (Euphorbia prostrata)*
Providence Mountains milkvetch (Astragalus nutans)
Prunus, Desert (Prunus eremophila)
Psoralea, Parish's (Rupertia rigida)
Puff-calyx gilia (Gilia aliquanta ssp. aliquanta)
Pulicaria (Pulicaria paludosa)*
Pullup muhly (Muhlenbergia filiformis)
Punchbowl clarkia (Clarkia bottae)
Puncture vine (Tribulus terrestris)*
Purple bird's beak (Cordylanthus parviflorus)
Purple clarkia (Clarkia purpurea ssp. quadrivulnera)
Purple cudweed (Gamochaeta ustulata)
Purple false-brome (Brachypodium distachyon)*
Purple false-gilia (Allophyllum divaricatum)
Purple mat
    [Common] (Nama demissa var. demissa)
    Coville's (Nama demissa var. covillei)
Purple monkeyflower (Erythranthe purpurea)
Purple needlegrass (Stipa pulchra)
Purple nightshade (Solanum xanti)
Purple owl's clover (Castilleja exserta ssp. exserta)
Purple reedgrass (Calamagrostis purpurascens)
Purple sage (Salvia leucophylla)
Purple salsify (Tragopogon porrifolius)*
Purple sanicle (Sanicula bipinnatifida)
Purpus's gilia (Gilia leptantha ssp. purpusii)
Pursh's milkvetch (Astragalus purshii var. lectulus)
Purslane,
    [Common] (Portulaca oleracea)*
    Lowland (Trianthema portulacastrum)
Purslane speedwell (Veronica peregrina ssp. xalapensis)
Pussypaws,
    One-seeded (Calyptridium monospermum)
    Parry's (Calyptridium parryi var. parryi)
    Pygmy (Calyptridium pygmaeum)
Pussytoes,
    Alpine (Antennaria media)
    Low (Antennaria dimorpha)
    Rosy (Antennaria rosea ssp. confinis)
Pygmy-flower rockjasmine (Androsace septentrionalis)
Pygmy hulsea (Hulsea vestita ssp. pygmaea)
Pygmyleaf, Spreading (Loeflingia squarrosa)
Pygmy linanthus (Leptosiphon pygmaeus ssp. continentalis)
Pygmy lotus (Acmispon haydonii)
Pygmy madia (Hemizonella minima)
Pygmy poppy (Canbya candida)
Pygmy pussypaws (Calyptridium pygmaeum)
Pygmyweed
   Australian (Crassula colligata ssp. lamprosperma)*
    [Common] (Crassula connata)
    Water (Crassula aquatica)
Pyrrocoma,
    Bear Valley (Pyrrocoma uniflora var. gossypina)
    Panicled (Pyrrocoma racemosa var. paniculata)
Quailbush (Atriplex lentiformis)
Quaking aspen (Populus tremuloides)
Quillwort,
    Bolander's (Isoetes bolanderi)
    Flowering (Triglochin scilloides)
Rabbitbrush,
    Black-banded (Ericameria paniculata)
    Ghostly rubber (Ericameria nauseosa var. hololeuca)
    Green (Ericameria teretifolia)
    Mojave rubber (Ericameria nauseosa ssp. mohavensis)
    Parry's (Ericameria parryi var. aspera)
    San Bernardino rubber (Ericameria nauseosa var. bernardina)
    Sharp-bracted rubber (Ericameria nauseosa var. ceruminosa )
    Sticky-leaved (Chrysothamnus viscidiflorus ssp. viscidiflorus)
    Threadleaf rubber (Ericameria nauseosa ssp. oreophila)
    White-flowered (Ericameria albida)
Rabbitsfoot grass (Polypogon monspeliensis)*
Rabbit thorn (Lycium pallidum var. oligospermum)
Ragged-leaf bahia (Hymenothrix dissecta)
Ragweed, Western (Ambrosia psilostachya)
Ragwort,
    Dwarf mountain (Senecio fremontii var. occidentalis)
    Mojave (Senecio mohavensis)
    San Bernardino (Packera bernardina)
    Tehachapi (Packera ionophylla)
Raillardella, Silky (Raillardella argentea)
Rainbow manzanita (Arctostaphylos rainbowensis)
Ramona clarkia (Clarkia similis)
Ramona horkelia (Horkelia truncata)
Rancheria clover (Trifolium albopurpureum)
Ranger's buttons (Angelica capitellata)
Raspberry, Western (Rubus leucodermis)
Rattail fescue (Festuca myuros)*
Rattlesnake weed (Euphorbia albomarginata)
Rattleweed,
    Braunton's (Astragalus brauntonii)
    Newberry's (Astragalus newberryi var. newberryi)
Rayless encelia (Encelia frutescens)
Rayless fleabane (Erigeron aphanactis var. congestus)
Rayless goldfields (Lasthenia glaberrima)
Rayless shaggy fleabane (Erigeron aphanactis var. aphanactis)
Rebman's silverback fern (Pentagramma rebmanii)
Red ammannia (Ammannia coccinea)
Red baneberry (Actaea rubra)
Redberry,
    Hollyleaf (Rhamnus ilicifolia)
    Island (Rhamnus pirifolia)
    Littleleaf (Rhamnus crocea)
Red brome (Bromus rubens)*
Redbud, Western (Cercis occidentalis)
Red bush monkeyflower (Diplacus puniceus)
Red clover (Trifolium pratense)*
Red elderberry (Sambucus racemosa var. racemosa)
Red fescue (Festuca rubra)
Red-flowered buckwheat (Eriogonum grande var. rubescens)
Red four o'clock (Mirabilis coccinea)
Red-gland spurge (Euphorbia melanadenia)
Red grama (Bouteloua trifida)
Red iceplant (Malephora crocea)*
Red maids,
    Brewer's (Calandrinia breweri)
    [Common] (Calandrinia menziesii)
    Seaside (Cistanthe maritima)
Red mariposa lily (Calochortus kennedyi var. kennedyi)
Red monardella (Monardella macrantha ssp. hallii)
Redowski's stickseed (Lappula redowskii var. redowskii)
Red-rayed hulsea (Hulsea heterochroma)
Red Rock Canyon monkeyflower (Erythranthe rhodopetra)
Red Rock tarplant (Deinandra arida)
Red-root cryptantha (Eremocarya micrantha var. micrantha)
Red sand-spurrey (Spergularia rubra)*
Red sand-verbena (Abronia maritima)
Red shanks (Adenostoma sparsifolium)
Red-skinned onion (Allium haematochiton)
Red spot clarkia (Clarkia speciosa ssp. polyantha)
Red-stem filaree (Erodium cicutarium)*
Red-stemmed monkeyflower (Erythranthe rubella)
Redstem spring beauty (Claytonia rubra ssp. rubra)
Red thistle (Cirsium arizonicum var. tenuisectum)
Red valerian (Centranthus ruber)*
Red willow (Salix laevigata)
Reflexed blazing star (Mentzelia reflexa)
Rein orchid,
    Alaska (Piperia unalascensis)
    [Common] (Piperia cooperi)
    Dense-flowered (Piperia elongata)
    Royal (Piperia transversa)
Retrorse desert four o'clock (Mirabilis laevis var. retrorsa)
Reveal's buckwheat (Eriogonum contiguum)
Rhatany,
    Littleleaf (Krameria erecta)
    White (Krameria bicolor)
Rhubarb, Wild (Rumex hymenosepalus)
Ribbed cryptantha (Johnstonella costata)
Ricegrass, Sand (Stipa hymenoides)
Rigid cryptantha (Cryptantha juniperensis)
Rigid fiddleneck (Amsinckia retrorsa)
Rigid hedge-nettle (Stachys rigida)
Rigid spineflower (Chorizanthe rigida)
Ring-stemmed bastard-sage (Eriogonum wrightii var. membranaceum)
Ringstem, Sticky (Anulocaulis annulatus)
Ripgut brome (Bromus diandrus)*
Ripley's aliciella (Aliciella ripleyi)
River bar bird's-foot trefoil (Acmispon denticulatus)
Riverside spineflower (Chorizanthe xanti var. leucotheca)
Rixford's buckwheat (Eriogonum rixfordii)
Rixford's rockwort (Scopulophila rixfordii)
Robust heartleaf sun cup (Chylismia cardiophylla ssp. robusta)
Robust Hoffmann's buckwheat (Eriogonum hoffmannii var. robustius)
Robust sun cup (Camissoniopsis robusta)
Robust vervain (Verbena lasiostachys var. scabrida)
Rock-brake, American (Cryptogramma acrostichoides)
Rock buckwheat (Eriogonum saxatile)
Rock Creek broomrape (Aphyllon validum)
Rock-cress,
    Arching (Boechera arcuata)
    Beautiful (Boechera pulchra)
    Bristly-leaved (Boechera rectissima)
    Broad-seeded (Boechera platysperma)
    California (Boechera californica)
    Mountain (Boechera retrofracta X)
    Parish's (Boechera parishii)
    Perennial (Boechera perennans)
    Shockley's (Boechera shockleyi)
    Slender beautiful (Boechera xylopoda)
    Yosemite (Boechera repanda)
Rock crossosoma (Crossosoma bigelovii)
Rock daisy
    [Common] (Perityle emoryi)
    Nevada (Perityle megalocephala var. megalocephala)
Rock dudleya (Dudleya saxosa ssp. aloides)
Rock gilia (Gilia scopulorum)
Rock goldenbush (Ericameria cuneata var. cuneata)
Rock hibiscus (Hibiscus denudatus)
Rock ivesia (Ivesia saxosa)
Rock-jasmine monkeyflower (Erythranthe androsacea)
Rock lady (Holmgrenanthe petrophila)
Rock melic (Melica stricta)
Rock mustard (Halimolobos jaegeri)
Rock-nettle,
    Annual (Eucnide rupestris)
    Desert (Eucnide urens)
Rock pennyroyal (Monardella robisonii)
Rock phacelia (Phacelia egena)
Rock-rose,
    Crimson spot (Cistus ladanifer var. maculatus)*
    Orchid (Cistus Xpurpureus)*
    Pink (Cistus incanus)*
    White-flowered (Cistus ladanifer var. albiflorus)*
Rock spiraea (Petrophytum caespitosum ssp. caespitosum)
Rockwort, Rixford's (Scopulophila rixfordii)
Rocky Mountain rush (Juncus saximontanus)
Ropevine (Clematis pauciflora)
Rose,
    Cliff (Purshia stansburyana)
    Interior (Rosa woodsii ssp. gratissima)
    Small-leaved (Rosa minutifolia)
    Wild (Rosa californica)
    Wood (Rosa gymnocarpa var. gymnocarpa)
Rose-and-white buckwheat (Eriogonum gracillimum)
Rose clover (Trifolium hirtum)*
Rose evening primrose (Oenothera rosea)*
Rose heath (Chaetopappa ericoides)
Rose sage (Salvia pachyphylla)
Rose snapdragon (Antirrhinum thompsonii)
Ross's sedge (Carex rossii)
Rosy apricot mallow (Sphaeralcea ambigua var. rosacea)
Rosy gilia (Gilia sinuata)
Rosy pussytoes (Antennaria rosea ssp. confinis)
Rosy spinystar (Coryphantha vivipara var rosea)
Rothrock's keckiella (Keckiella rothrockii var. rothrockii)
Rothrock's nama (Nama rothrockii)
Rothrock's sagebrush (Artemisia rothrockii)
Rough cat's ear (Hypochaeris radicata)*
Rough hairy golden-aster (Heterotheca villosa var. scabra)
Rough joint-fir (Ephedra aspera)
Rough menodora (Menodora scabra)
Roughseed cryptantha (Cryptantha flavoculata)
Round-fruited bladderpod (Peritoma arborea var. globosa)
Round-fruit yellowcress (Rorippa sphaerocarpa)
Roundleaf geranium (Geranium rotundifolium)*
Roundleaf leather root (Hoita orbicularis)
Roundleaf oxytheca (Oxytheca perfoliata)
Round-leaved boykinia (Boykinia rotundifolia)
Round-leaved bush mallow (Malacothamnus orbiculatus)
Round-leaved phacelia (Phacelia rotundifolia)
Royal desert lupine (Lupinus odoratus)
Royal goldfields (Lasthenia coronaria)
Royal penstemon (Penstemon speciosus)
Royal rein orchid (Piperia transversa)
Rubber rabbitbrush,
    Ghostly (Ericameria nauseosa var. hololeuca)
    Mojave (Chrysothamnus nauseosus ssp. mohavensis)
    San Bernardino (Ericameria nauseosa var. bernardina)
    Sharp-bracted (Ericameria nauseosa var. ceruminosa)
    Threadleaf (Chrysothamnus nauseosus ssp. consimilis)
Rusby's desert mallow (Sphaeralcea rusbyi var. eremicola)
Rush,
    Basket (Juncus textilis)
    Brown-headed (Juncus phaeocephalus var. paniculatus)
    Common toad (Juncus bufonius var. bufonius)
    Coville's (Juncus covillei)
    Clustered toad (Juncus bufonius var. congestus)
    Iris-leaved (Juncus xiphioides)
    Long-anthered (Juncus macrandus)
    Long-leaved (Juncus macrophyllus)
    Mariposa (Juncus dubius)
    Mexican (Juncus mexicanus)
    Moss (Juncus bryoides)
    Pacific (Juncus effusus ssp. pacificus)
    Pacific wood (Luzula comosa)
    Rocky Mountain (Juncus saximontanus)
    Spiny (Juncus acutus ssp. leopoldii)
    Spreading (Juncus patens)
    Straightleaf (Juncus orthophyllus)
    Tiehm's (Juncus tiehmii)
    Western toad (Juncus bufonius var. occidentalis)
    Wire (Juncus balticus)
    Wrinkled (Juncus rugulosus)
Rush bluegrass (Poa secunda ssp. juncifolia)
Rush milkweed (Asclepias subulata)
Rush seepweed (Suaeda nigra)
Rush-rose, Peak (Crocanthemum scoparium var. vulgare)
Russian knapweed (Rhaponticum repens)*
Russian thistle (Salsola tragus)*
Rusty-haired popcorn flower (Plagiobothrys nothofulvus)
Rusty slender sedge (Carex subfusca)
Rydberg's horkelia (Horkelia rydbergii)
Ryegrass (Festuca perennis)*
Sacapellote (Acourtia microcephala)
Sacred datura (Datura wrightii)
Safflower (Carthamus tinctorius)*
Sage,
    Black (Salvia mellifera)
    Blue (Salvia dorrii var. dorrii)
    Brandegee's (Salvia brandegeei)
    Cleveland's (Salvia clevelandii)
    Creeping (Salvia sonomensis)
    Crimson pitcher (Salvia spathacea)
    Death Valley (Salvia funerea)
    Desert (Salvia eremostachya)
    Fragrant pitcher (Lepechinia fragrans)
    Hairy blue (Salvia dorrii var. pilosa)
    Munz's (Salvia munzii)
    Purple (Salvia leucophylla)
    Rose (Salvia pachyphylla)
    Thistle (Salvia carduacea)
    Vasey's (Salvia vaseyi)
    White (Salvia apiana)
Sagebrush,
    Basin (Artemisia tridentata ssp. tridentata)
    Black (Artemisia nova)
    California (Artemisia californica)
    Flat (Artemisia bigelovii)
    Island (Artemisia nesiotica)
    Mountain (Artemisia tridentata ssp. vaseyana)
    Parish's (Artemisia tridentata ssp. parishii)
    Rothrock's (Artemisia rothrockii)
Sagebrush sedge (Carex filifolia var. erostrata)
Saguaro, Giant (Carnegiea gigantea)
Saharan mustard (Brassica tournefortii)*
Salsify,
    Purple (Tragopogon porrifolius)*
    Yellow (Tragopogon dubius)*
Saltbush,
    Arrowleaf (Atriplex prostrata)*
    Australian (Atriplex semibaccata)*
    Beach (Atriplex leucophylla)
    Caleb (Atriplex canescens var. laciniata)
    California (Extriplex californica)
    Coulter's (Atriplex coulteri)
    Four-wing (Atriplex canescens var. canescens)
    Pacific (Atriplex pacifica)
    Parry's (Atriplex parryi)
    Shadscale (Atriplex confertifolia)
    Silverscale (Atriplex argentea)
    Slenderleaf (Atriplex canescens var. linearis)
    Swamp (Atriplex amnicola)*
    Torrey's (Atriplex torreyi var. torreyi)
    Watson's (Atriplex watsonii)
    Waxy (Atriplex glauca)*
    Wheelscale (Atriplex elegans var. fasciculata)
Salt cedar (Tamarix ramosissima)*
Salt grass (Distichlis spicata)
Salt marsh baccharis (Baccharis glutinosa)
Salt marsh bird's beak (Chloropyron maritimum ssp. maritimum)
Salt marsh dodder (Cuscuta pacifica var. pacifica)
Salt marsh fleabane (Pluchea odorata var. odorata)
Salt marsh sand-spurrey (Spergularia marina)
Salton milkvetch (Astragalus crotalariae)
Saltwort (Batis maritima)
San Antonio Canyon bedstraw (Galium angustifolium ssp. gabrielense)
San Bernardino aster (Symphyotrichum defoliatum)
San Bernardino beardtongue (Penstemon caesius)
San Bernardino bluegrass (Poa atropurpurea)
San Bernardino buckwheat (Eriogonum microthecum var. corymbosoides)
San Bernardino mountain onion (Allium monticola)
San Bernardino Mountains alumroot (Heuchera parishii)
San Bernardino Mountains bladderpod (Physaria kingii ssp. bernardina)
San Bernardino Mountains dudleya (Dudleya abramsii ssp. affinis)
San Bernardino Mountains monkeyflower (Erythranthe exigua)
San Bernardino Mountains owl's clover (Castilleja lasiorhyncha)
San Bernardino ragwort (Packera bernardina)
San Bernardino rubber rabbitbrush (Ericameria nauseosa var. bernardina)
San Bernardino showy gilia (Gilia cana ssp. bernardina)
San Bernardino sun cup (Camissoniopsis confusa)
San Clemente Island bird's-foot trefoil (Acmispon argophyllus var. adsurgens)
San Clemente Island bush mallow (Malacothamnus clementinus)
Sandbar willow (Salix exigua var. exigua)
Sand blazing star (Mentzelia involucrata)
Sand cress (Calyptridium monandrum)
Sand-dune bluegrass (Poa douglasii)
Sand food (Pholisma sonorae)
Sand gilia (Aliciella triodon)
San Diego ambrosia (Ambrosia pumila)
San Diego button-celery (Eryngium aristulatum var. parishii)
San Diego chamise (Adenostoma fasciculatum var. obtusifolium)
San Diego County goldeneye (Bahiopsis laciniata)
San Diego County needlegrass (Stipa diegoensis)
San Diego gilia (Gilia diegensis)
San Diego gumplant (Grindelia hallii)
San Diego hulsea (Hulsea californica)
San Diego mountain-mahogany (Cercocarpus minutiflorus)
San Diego pea (Lathyrus vestitus var. alefeldii)
San Diego satureja (Clinopodium chandleri)
San Diego sedge (Carex spissa)
San Diego tarplant (Deinandra paniculata)
San Diego thornmint (Acanthomintha ilicifolia)
San Diego wreathplant (Stephanomeria diegensis)
San Diego yerba santa (Eriodictyon trichocalyx var. lanatum)
Sand-lettuce (Dudleya caespitosa)
Sand lupine (Lupinus brevicaulis)
Sandmat (Cardionema ramosissimum)
Sandpaper plant (Petalonyx thurberi ssp. thurberi)
Sandpaper plant, Shinyleaf (Petalonyx nitidus)
Sand plantain (Plantago arenaria)*
Sand ricegrass (Stipa hymenoides)
Sand spikerush (Eleocharis montevidensis)
Sand-spurrey,
    Boccone's (Spergularia bocconi)*
    Hairy (Spergularia villosa)*
    Red (Spergularia rubra)*
    Salt marsh (Spergularia marina)
    Sticky (Spergularia macrotheca var. macrotheca)
Sand-verbena,
    Chaparral (Abronia villosa var. aurita)
    Desert (Abronia villosa var. villosa)
    Mojave (Abronia pogonantha)
    Pink (Abronia umbellata var. umbellata)
    Red (Abronia maritima)
    White (Abronia turbinata)
Sandwort,
    Annual (Sabulina pusilla)
    Bear Valley (Eremogone ursina)
    Brittle (Sabulina nuttallii var. gracilis)
    Desert (Eremogone macradenia var. macradenia)
    Forest camp (Eremogone macradenia var. arcuifolia)
    King's (Eremogone kingii var. glabrescens)
    Spreading (Arenaria lanuginosa var. saxosa)
San Felipe dyssodia (Adenophyllum porophylloides)
San Fernando Valley spineflower (Chorizanthe parryi var. fernandina)
San Gabriel beardtongue (Penstemon labrosus)
San Gabriel bedstraw (Galium grande)
San Gabriel bluecup (Githopsis diffusa ssp. diffusa)
San Gabriel linanthus (Linanthus concinnus)
San Gabriel manzanita (Arctostaphylos glandulosa ssp. gabrielensis)
San Gabriel Mountains dudleya (Dudleya densiflora)
San Gabriel Mountains gilia (Gilia ochroleuca ssp. vivida)
San Gabriel Mountains hulsea (Hulsea vestita ssp. gabrielensis)
San Gabriel Mountains leather oak (Quercus durata var. gabrielensis)
San Gabriel River dudleya (Dudleya cymosa ssp. crebrifolia)
Sanicle,
    Pacific (Sanicula crassicaulis)
    Poison (Sanicula bipinnata)
    Purple (Sanicula bipinnatifida)
    Sierra (Sanicula graveolens)
San Jacinto beardtongue (Penstemon clevelandii var. connatus)
San Jacinto buckwheat (Eriogonum apiculatum)
San Jacinto lupine (Lupinus hyacinthinus)
San Jacinto Mountains bedstraw (Galium angustifolium ssp. jacinticum)
San Jacinto Mountains fleabane (Erigeron breweri var. jacinteus)
San Jacinto Mountains keckiella (Keckiella rothrockii var. jacintensis)
San Jacinto prickly phlox (Linanthus jaegeri)
San Joaquin adobe sunburst (Pseudobahia peirsonii)
San Luis Obispo milkvetch (Astragalus curtipes)
San Miguel Island bedstraw (Galium californicum ssp. miguelense)
San Miguel Island deerweed (Acmispon dendroideus var. veatchii)
San Miguel milkvetch (Astragalus miguelensis)
Santa Ana River woolstar (Eriastrum densifolium ssp. sanctorum)
Santa Barbara Island buckwheat (Eriogonum giganteum var. compactum)
Santa Barbara Island dudleya (Dudleya traskiae)
Santa Barbara milkvetch (Astragalus trichopodus var. phoxus)
Santa Catalina Island ironwood (Lyonothamnus floribundus ssp. floribundus)
Santa Catalina Island manzanita (Arctostaphylos catalinae)
Santa Cruz Island bird's-foot trefoil (Acmispon argophyllus var. niveus)
Santa Cruz Island buckwheat (Eriogonum arborescens)
Santa Cruz Island bush mallow (Malacothamnus fasciculatus var. nesioticus)
Santa Cruz Island fringe-pod (Thysanocarpus conchuliferus)
Santa Cruz Island gooseberry (Ribes thacherianum)
Santa Monica Mountains manzanita, see Transverse Range manzanita
Santa Rosa basalt brodiaea (Brodiaea santarosae)
Santa Rosa Island manzanita (Arctostaphylos confertiflora)
Santa Rosa Island torrey pine (Pinus torreyana ssp. insularis)
Santa Rosa Mountains linanthus (Leptosiphon floribundus ssp. hallii)
Santa Susana tarplant (Deinandra minthornii)
Santa Ynez wild buckwheat (Eriogonum cithariforme var. agninum)
Santolina pincushion (Chaenactis santolinoides)
Sanvitalia, Abert's (Sanvitalia abertii)
Sapphire woolstar (Eriastrum sapphirinum ssp. sapphirinum)
Satintail, California (Imperata brevifolia)
Satureja, San Diego (Clinopodium chandleri)
Savory, Monkeyflower (Clinopodium mimuloides)
Sawatch knotweed (Polygonum sawatchense ssp. sawatchense)
Sawtooth goldenbush (Hazardia squarrosa var. grindelioides)
Saxifrage, California (Micranthes californica)
Scalebroom (Lepidospartum squamatum)
Scalebud (Anisocoma acaulis)
Scalloped moonwort (Botrychium crenulatum)
Scaly cloak fern (Astrolepis cochisensis)
Scaly-stemmed sand plant (Pholisma arenarium)
Scarlet bugler (Penstemon centranthifolius)
Scarlet gaura (Oenothera suffrutescens)
Scarlet larkspur (Delphinium cardinale)
Scarlet lobelia (Lobelia cardinalis var. pseudosplendens)
Scarlet milkvetch (Astragalus coccineus)
Scarlet monkeyflower (Erythranthe cardinalis)
Scarlet pimpernel (Lysimachia arvensis)*
Scarlet spiderling (Boerhavia coccinea)
Scented cryptantha (Cryptantha utahensis)
Schott's calico (Loeseliastrum schottii)
Schott's indigo bush (Psorothamnus schottii)
Scouler's St. John's wort (Hypericum scouleri)
Scouler's willow (Salix scouleriana)
Screwbean mesquite (Prosopis pubescens)
Scrub aster (Dieteria asteroides var. asteroides)
Scrub lotus (Acmispon argyraeus var. multicaulis)
Scrub oak,
    Channel Island (Quercus pacifica)
    Coastal (Quercus dumosa)
    Desert (Quercus john-tuckeri)
    Inland (Quercus berberidifolia)
Sea beet (Beta vulgaris ssp. maritima)
Sea-blite,
    Estuary (Suaeda esteroa)
    Woolly (Suaeda taxifolia)
Seacliff buckwheat (Eriogonum parvifolium)
Sea dahlia (Leptosyne maritima)
Sea fig (Carpobrotus chilensis)*
Sea-lavender (Limonium californicum)
Sea-pink, California (Armeria maritima ssp. californica)
Searls' prairie clover (Dalea searlsiae)
Sea rocket (Cakile maritima)*
Seashore bentgrass (Agrostis pallens)
Seaside brome (Bromus sitchensis var. maritimus)
Seaside daisy (Erigeron glaucus)
Seaside fiddleneck (Amsinckia spectabilis var. spectabilis)
Seaside petunia, see Wild petunia
Seaside red maids (Cistanthe maritima)
Sedge,
    Black (Schoenus nigricans)
    Bolander's (Carex bolanderi)
    Clustered field (Carex praegracilis)
    Dense (Carex densa)
    Forest (Carex multicaulis)
    Fragile-sheathed (Carex fracta)
    Golden (Carex aurea)
    Ross's sedge (Carex rossii)
    Rusty slender (Carex subfusca)
    Sagebrush (Carex filifolia var. erostrata)
    San Diego (Carex spissa)
    Smooth-fruited (Carex heteroneura)
    Sturdy (Carex alma)
    Tall flat (Cyperus eragrostis)
    Triangular-fruit (Carex triquetra)
    Western rough (Carex senta)
    Woolly (Carex pellita)
Seepweed, Rush (Suaeda nigra)
Self-heal (Prunella vulgaris var. lanceolata)
Senecio, Bush (Senecio flaccidus var. douglasii)
Senna,
    Bladder (Colutea arborescens)*
    Coues' (Senna covesii)
    Desert (Senna armata)
    Silver (Senna artemisioides)
Sequoia, Giant (Sequoiadendron giganteum)*
Serviceberry, Utah (Amelanchier utahensis)
Shadscale saltbush (Atriplex confertifolia)
Shaggy-flowered woolstar (Eriastrum sapphirinum ssp. dasyanthum)
Shaggy-haired alumroot (Heuchera hirsutissima)
Shaggy hawkweed (Hieracium horridum)
Sharp-bracted rubber rabbitbrush (Ericameria nauseosa var. ceruminosa)
Sharpleaf cancerwort (Kickxia elatine)*
Sharpnut cryptantha (Cryptantha oxygona)
Shaw's agave (Agave shawii var. shawii)
Sheep sorrel (Rumex acetosella)*
Shelton's violet (Viola sheltonii)
Shepherd's purse (Capsella bursa-pastoris)*
Shining chickweed (Stellaria nitens)
Shining milkvetch (Astragalus lentiginosus var. micans)
Shining willow (Salix lasiandra var. lasiandra)
Shinyleaf sandpaper plant (Petalonyx nitidus)
Shiny lomatium (Lomatium lucidum)
Shiny peppergrass (Lepidium nitidum)
Shockley's goldenheads (Acamptopappus shockleyi)
Shockley's prickleleaf (Hecastocleis shockleyi)
Shockley's rock-cress (Boechera shockleyi)
Shooting star,
    Alpine (Primula tetrandra)
    [Common] (Primula clevelandii var. clevelandii)
    Foothill (Primula hendersonii)
    Fragrant (Primula fragrans)
    Island (Primula clevelandii ssp. insularis)
Shore grass (Distichlis littoralis)
Shortawn foxtail (Alopecurus aequalis var. aequalis)
Short-bannered coastal lotus (Acmispon brevivexillus var. brevivexillus)
Shortflower buckwheat (Eriogonum brachyanthum)
Short-flowered California dodder (Cuscuta occidentalis)
Short-fruited filaree (Erodium brachycarpum)*
Short-joint beavertail cactus (Opuntia basilaris var. brachyclada)
Shortleaf baccharis (Baccharis brachyphylla)
Short-leaved cliff-aster (Malacothrix saxatilis var. tenuifolia)
Short-leaved squirreltail (Elymus elymoides ssp. brevifolius)
Short-lobed broomrape (Aphyllon parishii ssp. brachylobum)
Shortpod mustard (Hirschfeldia incana)*
Shortray fleabane (Erigeron lonchophyllus)
Short-stemmed bastard sage (Eriogonum wrightii var. subscaposum)
Short-winged deerweed (Acmispon glaber var. brevialatus)
Showy Brewer's lupine (Lupinus breweri var. grandiflorus)
Showy cryptantha (Cryptantha muricata var. muricata)
Showy cycladenia (Cycladenia humilis var. venusta)
Showy gilia (Gilia cana ssp. speciformis)
Showy island snapdragon (Gambelia speciosa)
Shrubby brickellbush (Brickellia frutescens)
Shrubby interior live oak (Quercus wislizeni var. frutescens)
Shrubby mallow (Abutilon abutiloides)*
Shrub live oak (Quercus turbinella)
Sibbaldia (Sibbaldia procumbens)
Siberian water-milfoil (Myriophyllum sibiricum)
Sicklegrass, Curved (Parapholis incurva)*
Sicklepod rock-cress, see Elegant rock-cress
Side-oats grama (Bouteoua curtipendula)
Sierra gooseberry (Ribes roezlii var. roezlii)
Sierra helianthella (Helianthella californica var. nevadensis)
Sierra hoary coffeeberry (Frangula californica ssp. cuspidata)
Sierra lewisia (Lewisia nevadensis)
Sierra man-root (Marah horrida)
Sierra nemophila (Nemophila spatulata)
Sierra Nevada lotus (Acmispon nevadensis var. nevadensis)
Sierra Nevada monkeyflower (Erythranthe sierrae)
Sierra onion (Allium campanulatum)
Sierra sanicle (Sanicula graveolens)
Sierra tansy mustard (Descurainia californica)
Sigmoid threadplant (Nemacladus sigmoideus)
Silktassel,
    Ashy (Garrya flavescens)
    Canyon (Garrya veatchii)
    Coast (Garrya elliptica)
    Fremont's (Garrya fremontii)
Silky dalea (Dalea mollis)
Silky deerweed (Acmispon procumbens var. procumbens)
Silky lupine (Lupinus elatus)
Silky raillardella (Raillardella argentea)
Silverback fern,
    Coastal (Pentagramma viscosa)
    Rebman's (Pentagramma rebmanii)
Silver beach bur (Ambrosia chamissonis)
Silver bush lupine (Lupinus albifrons var. albifrons)
Silver cholla (Cylindropuntia echinocarpa)
Silver-haired ivesia (Ivesia argyrocoma var. argyrocoma)
Silver Lake daisy (Leucosyris arida)
Silverleaf horse-nettle (Solanum elaeagnifolium)*
Silver lotus (Acmispon argophyllus var. argophyllus)
Silver puffs (Uropappus lindleyi)
Silverscale saltbush (Atriplex argentea)
Silver senna (Senna artemisioides)*
Silverweed
    Common (Potentilla anserina ssp. anserina)
    Pacific (Potentilla anserina ssp. pacific)
Silver wormwood (Artemisia ludoviciana ssp. ludoviciana)
Silvery false-lupine (Thermopsis californica var. argentata)
Silvery lupine (Lupinus argenteus var. argenteus)
Simpson's buckwheat (Eriogonum microthecum var. simpsonii)
Singleleaf pinyon pine (Pinus monophylla)
Single-rosetted desert agave (Agave deserti var. simplex)
Single-toothed sticky cinquefoil (Drymocallis glandulosa var. viscida)
Six-weeks grass (Festuca octoflora)
Skeleton-plant, Thorny (Pleiacanthus spinosus)
Skullcap,
    Common (Scutellaria tuberosa)
    Grayleaf (Scutellaria siphocampyloides)
    Southern (Scutellaria bolanderi ssp. austromontana)
Skunkbrush (Rhus aromatica)
Sky lupine (Lupinus nanus)
Sky pilot, Western (Polemonium occidentale)
Sleepy catchfly (Silene antirrhina)
Slender beautiful rock-cress (Boechera xylopoda)
Slender bedstraw (Galium angustifolium ssp. gracillimum)
Slender buckwheat (Eriogonum gracile var. gracile)
Slender cinquefoil (Potentilla gracilis var. fastigiata)
Slender cottonweed (Micropus californicus var. californicus)
Slender cryptantha (Cryptantha gracilis)
Slender draba (Draba albertina)
Slender everlasting (Pseudognaphalium thermale)
Slender goldenweed (Xanthisma gracile)
Slender hairgrass (Deschampsia elongata)
Slenderleaf collomia (Collomia linearis)
Slenderleaf saltbush (Atriplex canescens var. linearis)
Slender-leaved iceplant (Mesembryanthemum nodiflorum)*
Slender-leaved sunflower (Helianthus gracilentus)
Slender lip fern (Myriopteris gracilis)
Slender-lobed four o'clock (Mirabilis tenuiloba)
Slender mariposa lily (Calochortus clavatus var. gracilis)
Slender oats (Avena barbata)*
Slender pectocarya (Pectocarya linearis ssp. ferocula)
Slender-petalled mustard (Thelypodium stenopetalum)
Slender phlox (Microsteris gracilis)
Slender-pod jewelflower (Caulanthus heterophyllus)
Slender popcorn flower (Plagiobothrys tenellus)
Slender poreleaf (Porophyllum gracile)
Slender spiderling (Boerhavia triquetra var. intermedia)
Slender tarplant (Deinandra fasciculata)
Slender threadplant (Nemacladus tenuis var. tenuis)
Slender vetch (Vicia hassei)
Slender volcanic gilia (Gilia ochroleuca ssp. exilis)
Slender wheat grass (Elymus trachycaulus ssp. trachycaulus)
Slender wild cabbage (Caulanthus major)
Slender woodland star (Lithophragma tenellum)
Slender woollyheads (Psilocarphus tenellus)
Slim aster (Symphyotrichum subulatum var. parviflorum)
Slim tridens (Triden muticus)
Slim vetch (Vicia ludoviciana ssp. ludoviciana)
Small evening primrose (Camissoniopsis micrantha)
Small fescue (Festuca microstachys)
Small-flower baby blue eyes (Nemophila menziesii var. integrifolia)
Smallflower bluecurls (Trichostema micranthum)
Small-flowered collinsia (Collinsia parviflora)
Small-flowered dwarf flax (Hesperolinon micranthum)
Small-flowered eucrypta (Eucrypta micrantha)
Small-flowered fiddleneck, see Rigid fiddleneck
Small-flowered groundsmoke (Gayophytum diffusum ssp. parviflorum)
Small-flowered lotus (Acmispon micranthus)
Small-flowered meconella (Meconella denticulata)
Small-flowered morning glory (Convolvulus simulans)
Small-flowered nightshade (Solanum americanum)
Small-flowered soap plant (Hooveria parviflora)
Small-flowered tamarisk (Tamarix parviflora)*
Smallflower monkeyflower (Erythranthe inconspicua)
Smallflower notchleaf phacelia (Phacelia crenulata var. minutiflora)
Smallflower threadplant (Nemacladus ramosissimus)
Smallflower woodland star (Lithophragma parviflorum var. parviflorum)
Small-head field clover (Trifolium microcephalum)
Small horseweed (Erigeron bonariensis)*
Small-leaved cream bush (Holodiscus discolor var. microphyllus)
Small-leaved nama (Nama pusillum)
Small-leaved rose (Rosa minutifolia)
Small-seeded spurge (Euphorbia polycarpa)
Small water-plantain buttercup (Ranunculus alismifolius var. alismellus)
Small wirelettuce (Stephanomeria exigua ssp. exigua)
Smartweed,
    Himalayan (Persicaria capitata)*
    Water (Persicaria punctata)
    Willow (Persicaria lapathifolia)
Smilo grass (Stipa miliacea var. miliacea)*
Smoke tree (Psorothamnus spinosus)
Smooth beggar-ticks (Bidens laevis)
Smooth boisduvalia (Epilobium campestre)
Smooth cat's ear (Hypochaeris glabra)*
Smooth flatsedge (Cyperus laevigatus)
Smooth-fruited sedge (Carex heteroneura)
Smooth many-flowered linanthus (Leptosiphon floribundus ssp. glaber)
Smooth scouring rush (Equisetum laevigatum)
Smooth showy penstemon (Penstemon spectabilis var. spectabilis)
Smooth-stemmed fagonia (Fagonia laevis)
Smooth tarplant (Centromadia pungens ssp. laevis)
Smooth willow-herb (Epilobium glaberrimum ssp. glaberrimum)
Smooth winter vetch (Vicia villosa ssp. varia)*
Snakeroot (Sanicula arguta)
Snake's head (Malacothrix coulteri)
Snakeweed,
    Broom (Gutierrezia sarothrae)
    Sticky (Gutierrezia microcephala)
Snapdragon,
    Desert twining (Antirrhinum filipes)
    Rose (Antirrhinum thompsonii)
    Showy island (Gambelia speciosa)
    Twining (Antirrhinum kelloggii)
    Violet (Antirrhinum nuttallianum ssp. nuttallianum)
    Violet twining (Maurandella antirrhiniflora)
    White (Antirrhinum coulterianum)
Sneezeweed,
    Bigelow's (Helenium bigelovii)
    [Common] (Helenium puberulum)
Snowberry,
    Creeping (Symphoricarpos mollis)
    Fragrant (Symphoricarpos longiflorus)
    Mountain (Symphoricarpos rotundifolius var. parishii)
    White (Symphoricarpos albus var. laevigatus)
Snowdrop bush (Styrax redivivus)
Snow plant (Sarcodes sanguinea)
Soap plant,
    [Common] (Chlorogalum pomeridianum var. pomeridianum)
    Small-flowered (Hooveria parviflora)
Soda straw (Angelica lineariloba)
Soft arnica (Arnica mollis)
Soft chess (Bromus hordeaceus)*
Soft-leaved paintbrush (Castilleja mollis)
Solitary-leaved alkali goldenbush (Isocoma acradenia var. eremophila)
Solomon's seal
    False (Maianthemum racemosum)
    Star-flowered false (Maianthemum stellatum)
Sonoran maiden fern (Pelazoneuron puberulum var. sonorensis)
Sonoran spurge (Euphorbia micromera)
Sourclover (Melilotus indicus)*
Southern alpine buckwheat (Eriogonum kennedyi var. alpigenum)
Southern bluecurls (Trichostema austromontanum ssp. austromontanum)
Southern bush monkeyflower (Diplacus australis)
Southern California draba (Draba corrugata)
Southern California morning glory (Calystegia macrostegia ssp. arida)
Southern California rock draba (Draba saxosa)
Southern cattail (Typha domingensis)
Southern Chinese houses (Collinsia concolor)
Southern coast live oak (Quercus agrifolia var. oxyadenia)
Southern foothill penstemon (Penstemon heterophyllus var. australis)
Southern goldenrod (Solidago confinis)
Southern honeysuckle (Lonicera subspicata var. denudata)
Southern island morning glory (Calystegia macrostegia ssp. amplissima)
Southern jewelflower (Streptanthus campestris)
Southern meadow thistle (Cirsium scariosum var. citrinum)
Southern miner's lettuce (Claytonia perfoliata ssp. mexicana)
Southern monardella (Monardella australis ssp. australis)
Southern mountain buckwheat (Eriogonum kennedyi var. austromontanum)
Southern mountain cutleaf (Hymenopappus filifolius var. lugens)
Southern mountain lupine (Lupinus albifrons var. austromontanus)
Southern mountain misery (Chamaebatia australis)
Southern mountain phacelia (Phacelia austromontana)
Southern mountain phlox (Phlox austromontana)
Southern mountain woolstar (Eriastrum densifolium ssp. austromontanum)
Southern Sierra bush monkeyflower (Diplacus calycinus)
Southern skullcap (Scutellaria bolanderi ssp. austromontana)
Southern tarplant (Centromadia parryi ssp. australis)
Southern tauschia (Tauschia arguta)
Southern woodland-gilia (Saltugilia australis)
Southwestern bushy bluestem (Andropogon glomeratus var. scabriglumis)
Sow-thistle,
    [Common] (Sonchus oleraceus)*
    Prickly (Sonchus asper ssp. asper)*
Spanish broom (Spartium junceum)*
Spanish clover (Acmispon americanus var. americanus)
Spanish needles,
    [Common] (Palafoxia arida var. arida)
    Giant (Palafoxia arida var. gigantea)
Sparse-flowered bog orchid (Platanthera sparsiflora)
Spearleaf brickellbush (Brickellia atractyloides var. arguta)
Spearleaf mountain dandelion (Agoseris retrorsa)
Spearmint (Mentha spicata)*
Speckled clarkia (Clarkia cylindrica ssp. cylindrica)
Spectacle pod (Dithyrea californica)
Speedwell,
    American (Veronica americana)
    Corn (Veronica arvensis) *
    Persian (Veronica persica)*
    Purslane (Veronica peregrina ssp. xalapensis)
    Thyme-leaved (Veronica serpyllifolia ssp. humifusa)*
    Water (Veronica anagallis-aquatica)*
Spicebush (Calycanthus occidentalis)*
Spiderling,
    Coulter's (Boerhavia coulteri var. palmeri)
    Scarlet (Boerhavia coccinea)
    Slender (Boerhavia triquetra var. intermedia)
    Wright's (Boerhavia wrightii)
Spike fescue (Festuca kingii)
Spike-moss,
    Ashy (Selaginella cinerascens)
    Bigelow's (Selaginella bigelovii)
    Bluish (Selaginella asprella)
    Desert (Selaginella eremophila)
    Hansen's (Selaginella hansenii)
    Watson's (Selaginella watsonii)
Spike primrose (Epilobium densiflorum)
Spikerush,
    Common (Eleocharis macrostachya)
    Needle (Eleocharis acicularis var. acicularis)
    Sand (Eleocharis montevidensis)
Spikeweed (Centromadia pungens ssp. pungens)
Spineflower,
    Brittle (Chorizanthe brevicornu var. brevicornu)
    California (Mucronea californica)
    Five-tooth (Chorizanthe watsonii)
    Fringed (Chorizanthe fimbriata var. fimbriata)
    Lace-fringed (Chorizanthe fimbriata var. laciniata)
    Leather (Lastarriaea coriacea)
    Mojave (Chorizanthe spinosa)
    Peninsular (Chorizanthe leptotheca)
    Pink (Chorizanthe membranacea)
    Prostrate (Chorizanthe procumbens)
    Rigid (Chorizanthe rigida)
    Riverside (Chorizanthe xanti var. leucotheca)
    San Fernando Valley (Chorizanthe parryi var. fernandina)
    Thurber's spineflower (Centrostegia thurberi)
    Wrinkled (Chorizanthe corrugata)
    Xantus' (Chorizanthe xanti var. xanti)
Spineless horsebrush (Tetradymia canescens)
Spiny aster (Chloracantha spinosa var. spinosa)
Spiny cocklebur (Xanthium spinosum)
Spiny greasebush (Glossopetalon spinescens var. aridum)
Spiny hopsage (Grayia spinosa)
Spiny menodora (Menodora spinescens)
Spiny rush (Juncus acutus ssp. leopoldii)
Spinystar,
    Alverson's (Coryphantha alversonii)
    Desert (Coryphantha chlorantha)
    Rosy (Coryphantha vivipara var. rosea)
Spiraea, Rock (Petrophyton caespitosum)
Splendid mariposa lily (Calochortus splendens)
Splendid woodland-gilia (Saltugilia splendens ssp. splendens)
Spotted buckwheat (Eriogonum maculatum)
Spotted coralroot (Corallorhiza maculata)
Spotted downingia (Downingia bella)
Spotted knapweed (Centaurea stoebe ssp. micranthos)*
Sprawling three-petal bedstraw (Galium trifidum ssp. columbianum)
Spreading dogbane (Apocynum androsaemifolium)
Spreading fleabane (Erigeron divergens)
Spreading gilia (Ipomopsis polycladon)
Spreading larkspur (Delphinium patens ssp. hepaticoideum)
Spreading navarretia (Navarretia fossalis)
Spreading phlox (Phlox diffusa)
Spreading pygmyleaf (Loeflingia squarrosa)
Spreading rush (Juncus patens)
Spreading sandwort (Arenaria lanuginosa var. saxosa)
Spring draba (Draba verna)
Spring lessingia (Lessingia tenuis)
Spring-parsley (Cymopterus aboriginum)
Spring vetch (Vicia sativa ssp. sativa )*
Spruce, Big-cone (Pseudotsuga macrocarpa)
Spurge,
    Abrams' (Euphorbia abramsiana)
    Arizona (Euphorbia arizonica)
    Beetle (Euphorbia eriantha)
    Bush (Euphorbia characias)*
    Caper (Euphorbia lathyris)*
    Carrizo Mountain (Euphorbia pediculifera)
    Cliff (Euphorbia misera)
    Dune (Euphorbia ocellata ssp. arenicola)
    Mojave (Euphorbia schizoloba)
    Parish's (Euphorbia parishii)
    Parry's (Euphorbia parryi)
    Petty (Euphorbia peplus)*
    Prostrate (Euphorbia prostrata)*
    Red-gland (Euphorbia melanadenia)
    Small-seeded (Euphorbia polycarpa)
    Sonoran (Euphorbia micromera)
    Terracina (Euphorbia terracina)*
    Thyme-leaved (Euphorbia serpyllifolia ssp. serpyllifolia)
    Warty (Euphorbia spathulata)
    Woodland (Euphorbia lurida)
    Yuma (Euphorbia setiloba)
Squawbush, see Skunkbrush
Squirreltail,
    California (Elymus elymoides ssp. californicus)
    Short-leaved (Elymus elymoides ssp. brevifolius)
Stansbury phlox (Phlox stansburyi ssp. stansburyi)
Star-flowered bedstraw (Galium stellatum)
Star-flowered false solomon's seal (Maianthemum stellatum)
Star gilia (Gilia stellata)
Star lily (Toxicoscordion fremontii)
Star thistle, Yellow (Centaurea solstitialis)*
Starwort,
    Meadow (Stellaria longipes ssp. longipes)
    Northern (Stellaria calycantha)
    Sticky (Schizotechium jamesianum)
Statice (Limonium sinuatum)*
St. Catherine's lace (Eriogonum giganteum var. giganteum)
Stemless evax (Hesperevax acaulis var. ambusticola)
Stemless mudwort (Limosella acaulis)
Stephanomeria,
    Chicory-leaved (Stephanomeria cichoriacea)
    Narrow-leaved (Stephanomeria tenuifolia)
Stephens' beardtongue (Penstemon stephensii)
Stickleaf (Mentzelia micrantha)
Stickseed (Lappula redowskii var. cupulata)
Sticky Chinese houses (Collinsia tinctoria)
Sticky cinquefoil
    Coastal (Drymocallis glandulosa var. wrangelliana)
    Double-toothed (Drymocallis glandulosa var. reflexa)
    Inland (Drymocallis glandulosa var. glandulosa)
    Single-toothed (Drymocallis glandulosa var. viscida)
Sticky dudleya (Dudleya viscida)
Sticky fagonia (Fagonia pachyacantha)
Sticky false-gilia (Allophyllum glutinosum)
Sticky geraea (Geraea viscida)
Sticky-leaved rabbitbrush (Chrysothamnus viscidiflorus ssp. viscidiflorus)
Sticky lessingia (Lessingia glandulifera var. glandulifera)
Sticky madia (Madia gracilis)
Sticky phacelia (Phacelia viscida var. viscida)
Sticky ringstem (Anulocaulis annulatus)
Sticky sand-spurrey (Spergularia macrotheca var. macrotheca)
Sticky snakeweed (Gutierrezia microcephala)
Sticky starwort (Schizotechium jamesianum)
Sticky tarplant, see Graceful tarplant
Stiffbranch bird's beak (Cordylanthus rigidus var. rigidus)
Stillingia,
    Broad-leaved (Stillingia spinulosa)
    Narrow-leaved (Stillingia linearifolia)
Stinging lupine (Lupinus hirsutissimus)
Stinkweed, Mojave (Cleomella obtusifolia)
Stipa, Giant (Stipa coronata)
Stitchwort, Douglas's (Sabulina douglasii)
St. John's wort, Scouler's (Hypericum scouleri)
Stonecrop,
    Broad-leaf (Sedum spathulifolium)
    Davidson's (Sedum niveum)
Straightleaf rush (Juncus orthophyllus)
Strawberry cactus (Mammillaria dioica)
Strawberry, Wild (Fragaria vesca)
Streambank lotus (Hosackia oblongifolia var. oblongifolia)
Stream orchid (Epipactis gigantea)
Streptanthella, Longbeak (Streptanthella longirostris)
Strigose lotus (Acmispon strigosus)
Strigose sun cup (Camissonia strigulosa)
Striped adobe lily (Fritillaria striata)
Striped horsebrush (Tetradymia argyraea)
Sturdy sedge (Carex alma)
Succulent lupine, see Arroyo lupine
Suffrutescent wallflower (Erysimum suffrutescens)
Sugar bush (Rhus ovata)
Sugar pine (Pinus lambertiana)
Suksdorf's monkeyflower (Erythranthe suksdorfii)
Sulphur-flowered buckwheat (Eriogonum umbellatum var. subaridum)
Sumac, Laurel (Malosma laurina)
Summer clover (Trifolium longipes ssp. hansenii)
Summer-holly,
    Flat leaf (Comarostaphylis diversifolia ssp. planifolia)
    Varied-leaf (Comarostaphylis diversifolia ssp. diversifolia)
Summer lupine (Lupinus formosus var. formosus)
Sun cup,
    California (Eulobus californicus)
    Common (Camissoniopsis bistorta)
    Hairy (Camissoniopsis hirtella)
    Heartleaf (Chylismia cardiophylla ssp. cardiophylla)
    Intermediate (Camissoniopsis intermedia)
    Jurupa Hills (Camissioniopsis ignota)
    Kern (Camissonia kernensis ssp. gilmanii)
    Little wiry (Camissonia pusilla)
    Longfruit (Eremothera chamaenerioides)
    Mojave (Camissonia campestris ssp. campestris)
    Narrow-leaf (Eremothera refracta)
    Palmer's (Tetrapteron palmeri)
    Robust (Camissoniopsis robusta)
    Robust heartleaf (Chylismia cardiophylla ssp. robusta)
    San Bernardino (Camissoniopsis confusa)
    Strigose (Camissonia strigulosa)
    Walker's (Chylismia walkeri ssp. tortilis)
    Wingfruit (Chylismiella pterosperma)
Sunflower,
    Algodones Dunes (Helianthus niveus ssp. tephrodes)
    Bush (Encelia californica)
    California (Helianthus californicus)
    Canyon (Venegasia carpesioides)
    Common (Helianthus annuus)
    Desert (Geraea canescens)
    Dune (Helianthus petiolaris ssp. canescens)
    Many-stem woolly (Eriophyllum multicaule)
    Nevin's woolly (Constancea nevinii)
    Slender-leaved (Helianthus gracilentus)
    Woolly (Eriophyllum lanatum var. obovatum)
Sunray (Enceliopsis nudicaulis)
Swamp knotweed (Persicaria amphibia)
Swamp saltbush (Atriplex amnicola)*
Sweet acacia (Vachellia farnesiana var. farnesiana)*
Sweet alyssum (Lobularia maritima)*
Sweetbush (Bebbia juncea var. aspera)
Sweet-cicely,
    Common (Osmorhiza brachypoda)
    Mountain (Osmorhiza berteroi)
Sweetclover,
    White (Melilotus albus)*
    Yellow (Melilotus officinalis)*
Sweet fennel (Foeniculum vulgare)*
Sweet pea,
    Canyon (Lathyrus vestitus var. vestitus)
    Perennial (Lathyrus latifolius)*
Sword fern,
    Cliff (Polystichum imbricans ssp. curtum)
    Western (Polystichum munitum)
Sycamore, Western (Platanus racemosa)
Syntrichopappus, Fremont's (Syntrichopappus fremontii)
Tackstem,
    White (Calycoseris wrightii)
    Yellow (Calycoseris parryi)
Tahquitz ivesia (Ivesia callida)
Tall fescue (Festuca arundinacea)*
Tall flat sedge (Cyperus eragrostis)
Tall hawksbeard (Crepis acuminata)
Tall horseweed (Erigeron canadensis)
Tall melica (Melica frutescens)
Tall skeleton weed (Eriogonum deflexum var. baratum)
Tall wheat grass (Elymus ponticus)*
Tanbark oak (Notholithocarpus densiflorus var. densiflorus)
Tansy-leaved phacelia (Phacelia tanacetifolia)
Tansy mustard,
    Appressed-fruited mountain (Descurainia incana)
    [Common] (Descurainia pinnata ssp. glabra)
    Mountain (Descurainia incisa ssp. incisa)
    Sierra (Descurainia californica)
    Western (Descurainia pinnata ssp. brachycarpa)
Tarragon, Wild (Artemisia dracunculus)
Tarplant,
    Graceful (Holocarpha virgata ssp. elongata)
    Heermann's (Holocarpha heermannii)
    Island (Deinandra clementina)
    Kellogg's (Deinandra kelloggii)
    Kern (Deinandra pallida)
    Mojave (Deinandra mohavensis)
    Otay (Deinandra conjugens)
    Red Rock (Deinandra arida)
    San Diego (Deinandra paniculata)
    Santa Susana (Deinandra minthornii)
    Slender (Deinandra fasciculata)
    Smooth (Centromadia pungens ssp. laevis)
    Southern (Centromadia parryi ssp. australis)
Tauschia,
    Parish's (Tauschia parishii)
    Southern (Tauschia arguta)
Tawny popcorn flower (Plagiobothrys fulvus var. campestris)
Tecate cypress (Hesperocyparis forbesii)
Tecopa bird's beak (Chloropyron tecopense)
Tehachapi buckwheat (Eriogonum callistum)
Tehachapi monardella (Monardella linoides ssp. oblonga)
Tehachapi ragwort (Packera ionophylla)
Tejon cryptantha (Cryptantha microstachys)
Tejon poppy (Eschscholzia lemmonii ssp. kernensis)
Telegraph weed (Heterotheca grandiflora)
Terracina spurge (Euphorbia terracina)*
Tetracoccus,
    Holly-leaved (Tetracoccus ilicifolius)
    Parry's (Tetracoccus dioicus)
Thickleaf yerba santa (Eriodictyon crassifolium var. crassifolium)
Thick-leaved ground-cherry (Physalis crassifolia)
Thick-leaved phacelia (Phacelia pachyphylla)
Thickpod milkvetch (Astragalus pachypus var. pachypus)
Thickstem wild cabbage (Caulanthus crassicaulis)
Thimbleberry (Rubus parviflorus)
Thimblehead, Wright's (Hymenothrix wrightii)
Thistle,
    Barbwire Russian (Salsola paulsenii)*
    Blessed (Centaurea benedictus)*
    Bull (Cirsium vulgare)*
    California (Cirsium occidentale var. californicum)
    Cobweb (Cirsium occidentale var. occidentale)
    Desert (Cirsium neomexicanum)
    Elk (Cirsium scariosum var. congdonii)
    Italian (Carduus pycnocephalus ssp. pycnocephalus)*
    Milk (Silybum marianum)*
    Mojave (Cirsium mohavense)
    Red (Cirsium arizonicum var. tenuisectum)
    Russian (Salsola tragus)*
    Southern meadow (Cirsium scariosum var. citrinum)
    Venus (Cirsium occidentale var. venustum)
    Yellow star (Centaurea solstitialis)*
Thistle sage (Salvia carduacea)
Thomas' buckwheat (Eriogonum thomasii)
Thompson's beardtongue (Penstemon thompsoniae)
Thornbush,
    Anderson's (Lycium andersonii)
    Fremont's (Lycium fremontii)
Thorne's buckwheat (Eriogonum thornei)
Thornmint,
    Heartleaf (Acanthomintha obovata ssp. cordata)
    San Diego (Acanthomintha ilicifolia)
Thorny skeleton-plant (Pleiacanthus spinosus)
Thoroughwort (Ageratina adenophora)*
Threadleaf rubber rabbitbrush (Ericameria nauseosa ssp. oreophila)
Thread-leaved brodiaea (Brodiaea filifolia)
Threadplant,
    Botany woman's (Nemacladus twisselmannii var. botanywomaniae)
    Comb-leaved (Nemacladus pinnatifidus)
    Desert (Nemacladus rubescens)
    Desert short-flowered (Nemacladus longiflorus var. breviflorus)
    Eastern (Nemacladus orientalis)
    Eastwood's (Nemacladus eastwoodiae)
    Glandular (Nemacladus glanduliferus)
    Long-flowered (Nemacladus longiflorus var. longiflorus)
    Parikh's (Nemacladus parikhiae)
    Sigmoid (Nemacladus sigmoideus)
    Slender (Nemacladus tenuis var. tenuis)
    Smallflower (Nemacladus ramosissimus)
Threadstem (Pterostegia drymarioides)
Threadstem carpet-weed (Mollugo cerviana)*
Threadstem gilia (Linanthus filiformis)
Threadstem madia (Madia exigua)
Three-awn (Aristida adscensionis)
Three-headed showy gilia (Gilia cana ssp. triceps)
Three-hearts (Tricardia watsonii)
Threelobe oxytheca (Sidotheca trilobata)
Three-petal bedstraw, see Sprawling three-petal bedstraw
Three-petal bedstraw, see Dwarf three-petal bedstraw
Three-spot (Osmadenia tenella)
Thurber's buckwheat (Eriogonum thurberi)
Thurber's penstemon (Penstemon thurberi)
Thurber's spineflower (Centrostegia thurberi)
Thurber's stemsucker (Pilostyles thurberi)
Thyme-leaved speedwell (Veronica serpyllifolia ssp. humifusa)*
Thyme-leaved spurge (Euphorbia serpyllifolia ssp. serpyllifolia)
Thymophylla, Five-needled (Thymophylla pentachaeta var. belenidium)
Tickseed,
    California (Leptosyne californica)
    Leafstem (Leptosyne calliopsidea)
Tidestrom's milkvetch (Astragalus tidestromii)
Tidy tips,
    Comanche Point (Layia leucopappa)
    White (Layia glandulosa)
     Yellow (Layia platyglossa)
Tiehm's rush (Juncus tiehmii)
Tiling's monkeyflower (Erythranthe tilingii)
Timberline phacelia (Phacelia hastata var. hastata)
Tinker's penny (Hypericum anagalloides)
Tiny bedstraw (Galium murale)*
Toadflax,
    Blue (Nuttallanthus texanus)
    Dalmatian (Linaria dalmatica ssp. dalmatica)*
Toad lily (Montia chamissoi)
Toad rush,
    Common (Juncus bufonius var. bufonius)
    Clustered (Juncus bufonius var. congestus)
    Western (Juncus bufonius var. occidentalis)
Tobacco,
    Coyote (Nicotiana attenuata)
    Desert (Nicotiana obtusifolia)
    Four-valved tobacco (Nicotiana quadrivalvis)
    Tree (Nicotiana glauca)
Tocalote (Centaurea melitensis)*
Tomato, Common (Lycopersicon esculentum)*
Tomcat clover (Trifolium willdenovii)
Toothed calicoflower (Downingia cuspidata)
Toothed wintergreen (Pyrola dentata)
Torrey pine (Pinus torreyana ssp. torreyana)
Torrey pine, Santa Rosa Island (Pinus torreyana ssp. insularis)
Torrey's amaranth (Amaranthus torreyi)
Torrey's eucrypta (Eucrypta chrysanthemifolia var. bipinnatifida)
Torrey's milkvetch (Astragalus calycosus var. calycosus)
Torrey's saltbush (Atriplex torreyi var. torreyi)
Torrey's scrub oak (Quercus acutidens)
Tower mustard (Turritis glabra)
Toyon (Heteromeles arbutifolia)
Tracy's woolstar (Eriastrum tracyi)
Trailing windmills (Allionia incarnata var. incarnata)
Transmontane gilia (Gilia transmontana)
Transverse fine-flower gilia (Gilia leptantha ssp. transversa)
Transverse Range manzanita (Arctostaphylos glandulosa ssp. mollis)
Trask's yerba santa (Eriodictyon traskiae ssp. smithii)
Tree clover (Trifolium ciliolatum)
Tree of heaven (Ailanthus altissima)*
Tree poppy, Channel Island (Dendromecon harfordii)
Tree tobacco (Nicotiana glauca)*
Trefoil, Pitch (Bituminaria bituminosa)*
Triangular-fruit sedge (Carex triquetra)
Tridens, Slim (Tridens muticus)
Triple-ribbed milkvetch (Astragalus tricarinatus)
Triteleia, Coast range (Triteleia lugens)
Trixis, California (Trixis californica var. californica)
True babystars (Leptosiphon bicolor)
Tubercled crowfoot (Ranunculus testiculatus)*
Tucker's oak (Quercus john-tuckeri)
Tufted evening primrose (Oenothera cespitosa ssp. marginata)
Tufted poppy (Eschscholzia caespitosa)
Tumble mustard (Sisymbrium altissimum)*
Turion duckweed (Lemna turionifera)
Turkey pea (Sanicula tuberosa)
Turkish rugging (Chorizanthe staticoides)
Turpentine-broom (Thamnosma montana)
Turpentine bush (Ericameria laricifolia)
Turtleback (Psathyrotes ramosissima)
Twayblade (Listera convallarioides)
Twiggy wreathplant (Stephanomeria virgata ssp. virgata)
Twinberry (Lonicera involucrata var. ledebourii)
Twining snapdragon (Antirrhinum kelloggii)
Twinleaf bedstraw (Galium bifolium)
Two-color phacelia (Phacelia bicolor)
Two-seeded milkvetch (Astragalus didymocarpus var. didymocarpus)
Two-tone everlasting (Pseudognaphalium biolettii)
Umbrella plant (Cyperus involucratus)*
Unicorn-plant, Desert (Proboscidea althaeifolia)
Urn-flowered alumroot, see Elegant alumroot
Utah agave (Agave utahensis)
Utah fendlerbush (Fendlerella utahensis)
Utah juniper (Juniperus osteosperma)
Utah miner's lettuce (Claytonia parviflora ssp. utahensis)
Utah penstemon (Penstemon utahensis)
Utah serviceberry (Amelanchier utahensis)
Valerian, Red (Centranthus ruber)*
Valley broomrape (Aphyllon vallicolum)
Valley cholla (Cylindropuntia bernardina)
Valley lupine (Lupinus microcarpus var. microcarpus)
Valley mayweed (Matricaria occidentalis)
Valley oak (Quercus lobata)
Valley popcorn flower (Plagiobothrys canescens var. canescens)
Varicolored buckwheat (Eriogonum umbellatum var. versicolor)
Varied-leaf summer-holly (Comarostaphylis diversifolia ssp. diversifolia)
Varied milkvetch (Astragalus lentiginosus var. variabilis)
Variegated dudleya (Dudleya variegata)
Vasey's prickly-pear (Opuntia vaseyi)
Vasey's sage (Salvia vaseyi)
Veatch's blazing star (Mentzelia veatchiana)
Velvet ash (Fraxinus velutina)
Velvet-mallow
    Newberry's (Horsfordia newberryi)
    Pink (Horsfordia alata)
Velvety false-lupine (Thermopsis californica var. semota)
Ventura marsh milkvetch (Astragalus pycnostachyus var. lanosissimus)
Venus looking-glass (Triodanis biflora)
Venus thistle (Cirsium occidentale var. venustum)
Verbena,
    Big-bract (Verbena bracteata)
    Goodding's (Verbena gooddingii)
Vernal water-starwort (Callitriche palustris)
Vervain,
    Mint-leaved (Verbena menthifolia)
    Robust (Verbena lasiostachys var. scabrida)
    Western (Verbena lasiostachys var. lasiostachys)
Vetch,
    American (Vicia americana ssp. americana)
    Hairy winter (Vicia villosa ssp. villosa)*
    Narrow-leaved (Vicia sativa ssp. nigra)*
    Slender (Vicia hassei)
    Slim (Vicia ludoviciana ssp. ludoviciana)
    Spring (Vicia sativa ssp. sativa)*
    Smooth winter (Vicia villosa ssp. varia)*
Viguiera, Parish's, see Parish's goldeneye
Vinegar weed (Trichostema lanceolatum)
Violet,
    Douglas's (Viola douglasii)
    Goosefoot (Viola purpurea ssp. purpurea)
    Gray-leaved (Violet pinetorum ssp. grisea)
    Macloskie's (Viola macloskeyi)
    Mojave goosefoot (Viola purpurea ssp. mohavensis)
    Oak (Viola purpurea ssp. quercetorum)
    Pine (Viola pinetorum ssp. pinetorum)
    Shelton's (Viola sheltonii)
    Western dog (Viola adunca ssp. adunca)
    Yellow (Viola lobata ssp. lobata)
Violet false-gilia (Allophyllum gilioides ssp. violaceum)
Violet snapdragon (Antirrhinum nuttallianum ssp. nuttallianum)
Violet twining snapdragon (Maurandella antirrhiniflora)
Virginia peppergrass (Lepidium virginicum ssp. virginicum)
Virgin River cryptantha (Cryptantha virginensis)
Virgin's bower (Clematis ligusticifolia)
Viscid lip fern (Myriopteris viscida)
Volcanic gilia (Gilia ochroleuca ssp. ochroleuca)
Walker's sun cup (Chylismia walkeri ssp. tortilis)
Wall bedstraw (Galium parisiense)*
Wallflower,
    Island (Erysimum insulare)
    Suffrutescent (Erysimum suffrutescens)
    Western (Erysimum capitatum var. capitatum)
Walnut,
    California black (female flowers) (Juglans californica var. californica)
    California black (fruit) (Juglans californica var. californica)
    California black (male flowers) (Juglans californica var. californica)
Wand buckwheat (Eriogonum roseum)
Wand mullein (Verbascum virgatum)*
Wand wirelettuce (Stephanomeria virgata ssp. pleurocarpa)
Warner Springs lessingia (Lessingia glandulifera var. tomentosa)
Warrior's plume (Pedicularis densiflora)
Wart cress (Lepidium didymum)*
Wartleaf ceanothus (Ceanothus papillosus)
Wartstem ceanothus (Ceanothus verrucosus)
Warty spurge (Euphorbia spathulata)
Water buttercup (Ranunculus aquatilis var. diffusus)
Water chickweed (Montia fontana)
Watercress (Nasturtium officinale)
Water-milfoil, Siberian (Myriophyllum sibiricum)
Water-parsley (Oenanthe sarmentosa)
Water parsnip (Berula erecta)
Water pennywort (Hydrocotyle verticillata)
Water pepper (Persicaria hydropiper)
Water-pimpernel (Samolus parviflorus)
Water plantain (Alisma triviale)
Water-plantain buttercup, Small (Ranunculus alismifolius var. alismellus)
Water pygmy weed (Crassula aquatica)
Water smartweed (Persicaria punctata)
Water speedwell (Veronica anagallis-aquatica)*
Water-starwort
    [Common] (Callitriche heterophylla var. bolanderi)
    Vernal (Callitriche palustris)
Waterweed, Western (Elodea nuttallii)
Wattle,
    Cootamundra (Acacia baileyana)*
    Golden (Acacia longifolia)*
Watson's saltbush (Atriplex watsonii)
Watson's spike-moss (Selaginella watsonii)
Wavyleaf bee blossom (Oenothera sinuosa)*
Wax currant (Ribes cereum var. cereum)
Wax-myrtle, California (Morella californica)
Waxy saltbush (Atriplex glauca)*
Weak bluegrass (Poa infirma)*
Wedge-leaf horkelia (Horkelia cuneata var. cuneata)
Weed's mariposa lily (Calochortus weedii var. weedii)
Weedy cudweed (Pseudognaphalium luteoalbum)*
Weeping love grass (Eragrostis curvula)*
Western azalea (Rhododendron occidentale)
Western bistort (Bistorta bistortoides)
Western blue flag (Iris missouriensis)
Western blue flax (Linum lewisii var. lewisii)
Western bog yellowcress (Rorippa palustris ssp. palustris)
Western buttercup (Ranunculus occidentalis)
Western chokecherry (Prunus virginiana var. demissa)
Western cowbane (Oxypolis occidentalis)
Western dichondra (Dichondra occidentalis)
Western dog violet (Viola adunca ssp. adunca)
Western false-indigo (Amorpha fruticosa)
Western field dodder (Cuscuta campestris)
Western gilia (Gilia aliquanta ssp. breviloba)
Western goldenrod (Euthamia occidentalis)
Western hackberry (Celtis reticulata)
Western hawksbeard (Crepis occidentalis)
Western lady's mantle (Aphanes occidentalis)
Western lanceleaf aster (Symphyotrichum lanceolatum ssp. hesperium)
Western maidenhair fern, see Five-finger fern
Western morning glory (Calystegia occidentalis ssp. fulcrata)
Western mountain aster (Symphyotrichum spathulatum var. spathulatum)
Western needlegrass (Stipa occidentalis ssp. occidentalis)
Western pearlwort (Sagina decumbens ssp. occidentalis)
Western poison oak (Toxicodendron diversilobum)
Western polypody (Polypodium hesperium)
Western ragweed (Ambrosia psilostachya)
Western raspberry (Rubus leucodermis)
Western redbud (Cercis occidentalis)
Western rough sedge (Carex senta)
Western sky pilot (Polemonium occidentale)
Western snakeroot (Ageratina occidentalis)
Western sword fern (Polystichum munitum)
Western sycamore (Platanus racemosa)
Western tansy mustard (Descurainia pinnata ssp. brachycarpa)
Western toad rush (Juncus bufonius var. occidentalis)
Western vervain (Verbena lasiostachys var. lasiostachys)
Western wallflower (Erysimum capitatum var. capitatum)
Western waterweed (Elodea nuttallii)
Weston's buckwheat (Eriogonum nudum var. westonii)
Wheat grass,
    Desert crested (Agropyron cristatum ssp. pectinatum)*
    Intermediate (Elymus hispidus)*
    Slender (Elymus trachycaulus ssp. trachycaulus)
    Tall (Elymus ponticus)*
Wheeler's cinquefoil (Potentilla wheeleri)
Wheelscale saltbush (Atriplex elegans var. fasciculata)
Whiskerbrush (Leptosiphon ciliatus)
Whispering bells (Emmenanthe penduliflora)
White alder (Alnus rhombifolia)
White catchfly (Silene verecunda)
White caterpillar phacelia (Phacelia cicutaria var. cicutaria)
White clover (Trifolium repens)*
White easter bonnets (Eriophyllum lanosum)
White false-gilia (Allophyllum integrifolium)
White fiesta flower (Pholistoma membranaceum)
White fir (Abies concolor)
White-flowered bluecup (Githopsis diffusa ssp. candida)
White-flowered bog orchid (Platanthera dilatata var. leucostachys)
White-flowered filaree (California macrophylla)
White-flowered hawkweed (Hieracium albiflorum)
White-flowered rabbitbrush (Ericameria albida)
White-flowered rock-rose (Cistus ladanifer var. albiflorus)*
White-flowering currant (Ribes indecorum)
White hedge-nettle (Stachys albens)
White-leaf monardella (Monardella hypoleuca ssp. hypoleuca)
White mallow (Eremalche exilis)
Whitemargin oxytheca (Sidotheca emarginata)
White Mountains horkelia (Horkelia hispidula)
White Mountains milkvetch (Astragalus lentiginosus var. semotus)
White Mountains wild buckwheat (Eriogonum gracilipes)
White nightshade (Solanum douglasii)
White pincushion (Chaenactis artemisiifolia)
Whiteplume wirelettuce (Stephanomeria exigua ssp. coronaria)
White rhatany (Krameria bicolor)
White sage (Salvia apiana)
White sand-verbena (Abronia turbinata)
White snapdragon (Antirrhinum coulterianum)
White snowberry (Symphoricarpos albus var. laevigatus)
Whitestem blazing star (Mentzelia albicaulis)
White-stem filaree (Erodium moschatum)*
White-stemmed milkweed (Asclepias albicans)
White sticky phacelia (Phacelia viscida var. albiflora)
White sweetclover (Melilotus albus)*
White tackstem (Calycoseris wrightii)
Whitethorn,
    Chaparral (Ceanothus leucodermis)
    Mountain (Ceanothus cordulatus)
White tidy tips (Layia glandulosa)
Whitetip clover (Trifolium variegatum)
White-veined wintergreen (Pyrola picta)
White-whorled lupine (Lupinus microcarpus var. densiflorus)
Whitney's locoweed (Astragalus whitneyi var. whitneyi)
Whorled dock (Rumex conglomeratus)*
Whorl-leaf penstemon (Keckiella ternata var. ternata)
Wide-leaved Parish's yampah (Perideridia parishii ssp. latifolia)
Wide-leaved rock goldenbush (Ericameria cuneata var. spathulata)
Wiggins's croton (Croton wigginsii)
Wilcox's woolstar (Eriastrum wilcoxii)
Wild cabbage,
    Slender (Caulanthus major)
    Thickstem (Caulanthus crassicaulis)
Wild carrot, American (Daucus pusillus)
Wild celery (Apiastrum angustifolium)
Wild cucumber (Marah macrocarpa)
Wild grape (Vitis girdiana)
Wild heliotrope (Heliotropium curassavicum var. oculatum)
Wild licorice (Glycyrrhiza lepidota)
Wild mock orange (Philadelphus lewisii)
Wild oxalis (Oxalis pilosa)
Wild peony (Paeonia californica)
Wild peppergrass (Lepidium virginicum ssp. menziesii)
Wild petunia (Petunia parviflora)
Wild radish (Raphanus sativus)*
Wild-rhubarb (Rumex hymenosepalus)
Wild rose (Rosa californica)
Wildrose Canyon buckwheat (Eriogonum eremicola)
Wildrye,
    Blue (Elymus glaucus ssp. glaucus)
    Creeping (Elymus triticoides)
    Giant (Elymus condensatus)
    Great Basin (Elymus cinereus)
    Pacific (Elymus pacificus)
Wild strawberry (Fragaria vesca)
Wild tarragon (Artemisia dracunculus)
Willow,
    Arroyo (Salix lasiolepis)
    Desert (Chilopsis linearis ssp. arcuata)
    Geyer's (Salix geyeriana)
    Goodding's black (Salix gooddingii)
    Hinds' narrowleaf (Salix exigua var. hindsiana)
    Lemmon's (Salix lemmonii)
    Red (Salix laevigata)
    Sandbar (Salix exigua var. exigua)
    Scouler's (Salix scouleriana)
    Shining (Salix lasiandra var. lasiandra)
Willow baccharis (Baccharis salicina)
Willow-herb,
    [Common] (Epilobium ciliatum ssp. ciliatum)
    Field (Epilobium brachycarpum)
    Glandular (Epilobium ciliatum ssp. glandulosum)
    Hall's (Epilobium hallianum)
    Milkflower (Epilobium lactiflorum)
    Oregon (Epilobium oregonense)
    Smooth (Epilobium glaberrimum ssp. glaberrimum)
Willowleaf lettuce (Lactuca saligna)*
Willow-leaved dock (Rumex californicus)
Willow smartweed (Persicaria lapathifolia)
Willowy monardella (Monardella viminea)
Windflower, Desert (Anemone tuberosa)
Winding mariposa lily (Calochortus flexuosus)
Windmill pink (Silene gallica)*
Windmills
    Hairy (Allionia incarnata var. villosa)
    Trailing (Allionia incarnata var. incarnata)
Wind poppy (Papaver heterophyllum)
Winged cryptantha (Johnstonella holoptera)
Winged pectocarya (Pectocarya penicillata)
Wingfruit sun cup (Chylismiella pterosperma)
Wingnut cryptantha (Cryptantha pterocarya)
Winter cress (Barbarea orthoceras)
Winterfat (Krascheninnikovia lanata)
Wintergreen,
    Bog (Pyrola asarifolia ssp. asarifolia)
    Lesser (Pyrola minor)
    Toothed (Pyrola dentata)
    White-veined (Pyrola picta)
Winter vetch,
    Hairy (Vicia villosa ssp. villosa)*
    Smooth (Vicia villosa ssp. varia)*
Wirelettuce,
    Deane's (Stephanomeria exigua ssp. deanei)
    Parry's (Stephanomeria parryi)
    Small wirelettuce (Stephanomeria exigua ssp. exigua)
    Wand (Stephanomeria virgata ssp. pleurocarpa)
    Whiteplume (Stephanomeria exigua ssp. coronaria)
Wire rush (Juncus balticus)
Wireweed (Rigiopappus leptocladus)
Wishbone bush (Mirabilis laevis var. crassifolia)
Wolf's cholla (Cylindropuntia wolfii)
Woodland-gilia
    Grant's (Saltugilia splendens ssp. grantii)
    Latimer's (Saltugilia latimeri)
    Southern (Saltugilia australis)
    Splendid (Saltugilia splendens ssp. splendens)
Woodland spurge (Euphorbia lurida)
Woodland star,
    Bolander's (Lithophragma bolanderi)
    [Common] (Lithophragma affine)
    Hillside (Lithophragma heterophyllum)
    Mission (Lithophragma cymbalaria)
    Slender (Lithophragma tenellum)
    Smallflower (Lithophragma parviflorum var. parviflorum)
Wood rose (Rosa gymnocarpa var. gymnocarpa)
Wood rush, Hairy (Luzula comosa)
Wood sorrel,
    Creeping (Oxalis corniculata)*
    Hairy (Oxalis pilosa)
Woody crinklemat (Tiquilia canescens var. canescens)
Woolly amsonia (Amsonia tomentosa)
Woolly angelica (Angelica tomentosa)
Woolly bluecurls (Trichostema lanatum)
Woolly brickellbush (Brickellia incana)
Woolly bur-sage (Ambrosia eriocentra)
Woolly chaparral pea (Pickeringia montana var. tomentosa)
Woolly daisy (Eriophyllum wallacei)
Woolly-fruited milkweed (Asclepias eriocarpa)
Woollyhead neststraw (Stylocline micropoides)
Woollyheads,
    Dwarf (Psilocarphus brevissimus var. brevissimus)
    Slender (Psilocarphus tenellus)
Woollyleaf ceanothus (Ceanothus tomentosus)
Woolly lomatium (Lomatium dasycarpum ssp. dasycarpum)
Woolly marigold (Baileya pleniradiata)
Woolly milkweed (Asclepias vestita)
Woolly mountain parsley (Oreonana vestita)
Woolly mullein (Verbascum thapsus)*
Woolly paintbrush (Castilleja foliolosa)
Woolly plantain (Plantago ovata var. fastigiata)
Woollypod, Bear Valley (Astragalus leucolobus)
Woollypod milkvetch (Astragalus purshii var. tinctus)
Woolly sea-blite (Suaeda taxifolia)
Woolly sedge (Carex pellita)
Woolly sunflower,
    [Common] (Eriophyllum lanatum var. obovatum)
    Many-stem (Eriophyllum multicaule)
    Nevin's (Constancea nevinii)
    Pringle's (Eriophyllum pringlei)
Woolstar,
    Desert (Eriastrum eremicum ssp. eremicum)
    Few-flowered (Eriastrum sparsiflorum)
    Giant (Eriastrum densifolium ssp. elongatum)
    Harwood's (Eriastrum harwoodii)
    Maroon-spotted (Eriastrum signatum)
    Miniature (Eriastrum diffusum)
    Mojave (Eriastrum densifolium ssp. mohavense)
    Santa Ana River (Eriastrum densifolium ssp. sanctorum)
    Sapphire (Eriastrum sapphirinum ssp. sapphirinum)
    Shaggy-flowered (Eriastrum sapphirinum ssp. dasyanthum)
    Southern mountain (Eriastrum densifolium ssp. austromontanum)
    Tracy's (Eriastrum tracyi)
    Wilcox's (Eriastrum wilcoxii)
Wooton's lip fern (Myriopteris wootonii)
Wormwood,
    Mountain (Artemisia ludoviciana ssp. incompta)
    Silver (Artemisia ludoviciana ssp. ludoviciana)
Wreathplant,
    San Diego (Stephanomeria diegensis)
    Twiggy (Stephanomeria virgata ssp. virgata)
Wright's bastard-sage (Eriogonum wrightii var. wrightii)
Wright's bedstraw (Galium wrightii)
Wright's beebrush (Aloysia wrightii)
Wright's buckwheat, see bastard-sage
Wright's collinsia (Collinsia torreyi var. wrightii)
Wright's cudweed (Pseudognaphalium canescens)
Wright's spiderling (Boerhavia wrightii)
Wright's thimblehead (Hymenothrix wrightii)
Wrinkled rush (Juncus rugulosus)
Wrinkled spineflower (Chorizanthe corrugata)
Xantus pincushion (Chaenactis xantiana)
Xantus' spineflower (Chorizanthe xanti var. xanti)
Yampah,
    Adobe (Perideridia pringlei)
    Parish's (Perideridia parishii ssp. parishii)
    Wide-leaved Parish's (Perideridia parishii ssp. latifolia)
Yarrow,
    [Common] (Achillea millefolium)
    Golden (Eriophyllum confertiflorum var. confertiflorum)
Yellow bird-of-paradise (Caesalpinia gilliesii)*
Yellow carpet (Blennosperma nana var. nana)
Yellow comet (Mentzelia affinis)
Yellowcress,
    Bluntleaf (Rorippa curvipes)
    Curvepod yellowcress (Rorippa curvisiliqua)
    Round-fruit (Rorippa sphaerocarpa)
    Western bog (Rorippa palustris ssp. palustris)
Yellow cryptantha (Oreocarya confertiflora)
Yellow cups (Chylismia brevipes ssp. brevipes)
Yellow-eyed grass (Sisyrinchium elmeri)
Yellow-eyed lupine (Lupinus flavoculatus)
Yellow-frocks (Eriophyllum ambiguum var. paleaceum)
Yellowheads (Trichoptilium incisum)
Yellow mariposa lily (Calochortus clavatus var. pallidus)
Yellow monkeyflower (Diplacus brevipes)
Yellow paintbrush (Castilleja plagiotoma)
Yellow penstemon (Keckiella antirrhinoides var. antirrhinoides)
Yellow peppergrass (Lepidium flavum)
Yellow pincushion (Chaenactis glabriuscula var. glabriuscula)
Yellow pine (Pinus ponderosa var. pacifica)
Yellow salsify (Tragopogon dubius)*
Yellow saucers (Malacothrix sonchoides)
Yellow star thistle (Centaurea solstitialis)*
Yellow sweetclover (Melilotus officinalis)*
Yellow tackstem (Calycoseris parryi)
Yellow-throated phacelia (Phacelia brachyloba)
Yellow tidy tips (Layia platyglossa)
Yellow turban (Eriogonum pusillum)
Yellow violet (Viola lobata ssp. lobata)
Yellow water-weed (Ludwigia peploides)*
Yerba amarilla (Mentzelia longiloba)
Yerba buena (Clinopodium douglasii)
Yerba mansa (Anemopsis californica)
Yerba santa,
    Bicolored (Eriodictyon crassifolium var. nigrescens)
    Hairy (Eriodictyon trichocalyx var. trichocalyx)
    San Diego (Eriodictyon trichocalyx var. lanatum)
    Thickleaf (Eriodictyon crassifolium var. crassifolium)
    Trask's (Eriodictyon traskiae ssp. smithii)
Yosemite rock-cress (Boechera repanda)
Yucca,
    Banana (Yucca baccata var. baccata)
    Chaparral (Hesperoyucca whipplei)
    Mojave (Yucca schidigera)
Yuma spurge (Euphorbia setiloba)
Zaca Lake manzanita, see Eastwood manzanita
Ziegler's aster (Dieteria canescens var. ziegleri)
Zig-zag groundsmoke (Gayophytum heterozygum)
Zygadene, Desert (Zigadenus brevibracteatus)