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 cloak fern (Notholaena californica)
California cliff brake (Pellaea mucronata var. 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 sunflower (Helianthus californicus)
California squirreltail (Elymus elymoides ssp. californicus)
California sun cup (Eulobus 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 (Jonstonella 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)
Del Mar manzanita (Arctostaphylos glandulosa ssp. crassifolia)
Delicate buttercup (Ranunculus hebecarpus)
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 var. 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 spinystar (Escobaria 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,
    Least (Lemna minuta)
    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)