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 (Paraserianthes 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 (Escobaria 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)
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] (Cleomella arborea var. arborea)
    King's (Physaria kingii ssp. kingii)
    Round-fruited (Cleomella 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 var. campanularia)
    Funnel (Phacelia campanularia var. vasiformis)
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, [Common] (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 pygmaeum)
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 microseris (Stebbinsoseris heterocarpa)
Brown turbans (Malperia tenuis)
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)
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 (Eriogonum 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)