Abert's sanvitalia (Sanvitalia abertii)
Abrams' alumroot (Heuchera abramsii)
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)
Adolphia, California (Adolphia californica)
African asparagus fern (Asparagus asparagoides)*
African daisy (Osteospermum ecklonis)*
African mustard (Malcolmia africana)*
Agave,
    Desert (Agave deserti)
    Shaw's (Agave shawii var. shawii)
    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 draba (Cusickiella douglasii)
Alkali goldenbush
    (Isocoma acradenia var. acradenia)
    (Isocoma acradena var. bracteosa)
    (Isocoma acradenia var. eremophila)
Alkali heath (Frankenia salina)
Alkali mallow (Malvella leprosa)
Alkali mariposa lily (Calochortus striatus)
Akali phacelia (Phacelia neglecta)
Alkali sacaton (Sporobolus airoides)
Alkali weed (Cressa truxillensis)
Allen's daisy (Pentachaeta aurea ssp. allenii)
Allseed, Four-leaf (Polycarpon tetraphyllum)*
Almond, Desert (Prunus fasciculata var. fasciculata)
Alpine aster (Oreostemma alpigenum var. andersonii)
Alpine gold hulsea (Hulsea algida)
Alpine gooseberry (Ribes lasianthum)
Alpine pearlwort (Sagina saginoides)
Alpine pussytoes (Antennaria media)
Alpine shooting star (Dodecatheon alpinum)
Alpine sulphur-flowered buckwheat (Eriogonum umbellatum var. minus)
Alumroot,
    Abrams' (Heuchera abramsii)
    Island (Heuchera maxima)
    Mount Laguna (Heuchera brevistaminea)
    Pink (Heuchera rubescens var. alpicola)
    San Bernardino Mountains (Heuchera parishii)
    Shaggy-haired (Heuchera hirsutissima)
    Urn-flowered (Heuchera caespitosa)
Alverson's spinystar (Coryphantha alversonii)
Alyssum,
    Desert (Lepidium fremontii var. fremontii)
    Sweet (Lobularia maritima)*
Amaranth,
    California (Amaranthus californicus)
    Fringed (Amaranthus fimbriatus)
    Pigweed (Amaranthus albus)*
    Prostrate (Amaranthus blitoides)
    Torrey's (Amaranthus torreyi)
Ambrosia, San Diego (Ambrosia pumila)
American bulrush (Schoenoplectus americanus)
American dogwood (Cornus sericea ssp. sericea)
American rock-brake (Cryptogramma agrostichoides)
American speedwell (Veronica americana)
American vetch (Vicia americana var. americana)
American wild carrot (Daucus pusillus)
Ammannia, Red (Ammannia coccinea)
Amsonia, Woolly (Amsonia tomentosa)
Anderson thornbush (Lycium andersonii)
Anderson's lupine (Lupinus andersonii)
Angelica, Woolly (Angelica tomentosa)
Angel's gilia, see Chaparral gilia
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 sandwort (Minuartia pusilla)
Antelope bush, see Desert bitterbrush
Apache plume (Fallugia paradoxa)
Apricot, Desert (Prunus fremontii)
Apricot mallow (Sphaeralcea ambigua var. ambigua)
Apricot mallow, Rosy (Sphaeralcea ambigua var. rosacea)
Aralia, California (Aralia californica)
Arched elegant rock-cress (Boechera arcuata)
Argus gilia (Gilia brecciarum ssp. neglecta)
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 (Chamaesyce arizonica)
Arrow weed (Pluchea sericea)
Arrowleaf (Pleurocoronis pluriseta)
Arrowleaf butterweed (Senecio triangularis)
Arrowleaf saltbush (Atriplex prostrata)*
Arrowscale (Atriplex covillei)
Arroyo lupine (Lupinus succulentus)
Arroyo willow (Salix lasiolepis)
Ash,
    California (Fraxinus dipetala)
    Velvet (Fraxinus velutina)
Ashy silktassel (Garrya flavescens)
Ashy spike-moss (Selaginella cinerascens)
Ashy-gray paintbrush (Castilleja cinerea)
Ashy-leaf buckwheat (Eriogonum cinereum)
Asian mustard, see Saharan mustard
Aster,
    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 saltbush (Atriplex semibaccata)*
Autumn dwarf gentian (Gentianella amarella ssp. acuta)
Aven Nelson's phacelia (Phacelia anelsonii)
Avens, Large-leaved (Geum macrophyllum var. perincisum)
Ayenia (Ayenia compacta)
Azalea, Western (Rhododendron occidentale)
Baby blue eyes,
    Eastwood's (Nemophila pulchella var. pulchella)
    (Nemophila menziesii var. integrifolia)
    (Nemophila menziesii var. menziesii)
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 (Schkuhria multiflora var. multiflora)
    Ragged-leaf (Amauriopsis dissecta)
Baja birdbush (Ornithostaphylos oppositifolia)
Baja navarretia (Navarretia peninsularis)
Bajada lupine (Lupinus concinnus)
Baldwin Lake linanthus (Linanthus killipii)
Balloon clover (Trifolium depauperatum var. truncatum)
Balsamroot, Deltoid (Balsamorhiza deltoidea)
Banana yucca (Yucca baccata)
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 rush (Juncus textilis)
Bassia, Five-hook (Bassia hyssopifolia)
Bastard toadflax, California (Comandra umbellata ssp. californica)
Bay, California (Umbellularia californica)
Beach primrose,
    Channel Islands (Camissoniopsis cheiranthifolia ssp. cheiranthifolia)
    [Common] (Camissonia cheiranthifolia ssp. suffruticosa)
Beach morning glory (Calystegia soldanella)
Beach saltbush (Atriplex leucophylla)
Beaked penstemon (Penstemon rostriflorus)
Bear Valley milkvetch (Astragalus lentiginosus var. sierrae)
Bear Valley pyrrocoma (Pyrrocoma uniflora var. gossypina)
Bear Valley sandwort (Eremogone ursina)
Bear Valley woollypod (Astragalus leucolobus)
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)
    San Bernardino (Penstemon caesius)
    San Gabriel (Penstemon labrosus)
    San Gabriel (yellow variant) (Penstemon labrosus)
    San Jacinto (Penstemon clevelandii var. connatus)
    Stephens' (Penstemon stephensii)
Beargrass,
    Chaparral (Nolina cismontana)
    [Common] (Nolina bigelovii)
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,
    Annual (Galium aparine)
    Boxwood-leaved (Galium buxifolium)
    Catalina Island (Galium catalinense)
    Climbing (Galium nuttallii ssp. nuttallii)
    Graceful (Galium porrigens var. porrigens)
    Hilend's bedstraw (Galium hilendiae ssp. hilendiae)
    Leafy (Galium angustifolium ssp. foliosum)
    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. andrewsii)
    Phlox-leaved (Galium andrewsii ssp. intermedium)
    San Antonio Canyon (Galium angustifolium ssp. gabrielense)
    San Jacinto Mountains (Galium angustifolium ssp. jacinticum)
    San Miguel Island (Galium californicum ssp. miguelense)
    Slender (Galium angustifolium ssp. gracillimum)
    Star-flowered (Galium stellatum)
    Three-petal (Galium trifidum ssp. columbianum)
    Three-petal (Galium trifidum ssp. subbiflorum)
    Tiny (Galium murale)*
    Twinleaf (Galium bifolium)
    Wall (Galium parisiense)*
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)
Bergamot mint (Mentha Xpiperita var. citrata)*
Bermuda buttercup (Oxalis pes-caprae)*
Bermuda grass (Cynodon dactylon)*
Bernardia (Bernardia incana)
Biennial cinquefoil (Potentilla biennis)
Big Bear checkerbloom (Sidalcea pedata)
Big Bear Valley phlox (Phlox dolichantha)
Big galleta grass (Hilaria rigida)
Big-berry manzanita (Arctostaphylos glauca)
Big-bract verbena (Verbena bracteata)
Big-cone spruce (Pseudotsuga macrocarpa)
Big-leaf maple (Acer macrophyllum)
Big-leaf mistletoe (Phoradendron macrophyllum)
Big-pod ceanothus (Ceanothus megacarpus var. megacarpus)
Bigelow's coreopsis (Leptosyne bigelovii)
Bigelow's desert four o'clock (Mirabilis laevis var. villosa)
Bigelow's monkeyflower (Mimulus bigelovii var. bigelovii)
Bigelow's monkeyflower (Mimulus bigelovii var. cuspidatus)
Bigelow's sneezeweed (Helenium bigelovii)
Bigelow's spike-moss (Selaginella bigelovii)
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. rigidus)
    Bristly (Cordylanthus rigidus ssp. setigerus)
    Nevin's (Cordylanthus nevinii)
    Orcutt's (Dicranostegia orcuttiana)
    Purple (Cordylanthus parviflorus)
    Salt marsh (Chloropyron maritimum ssp. maritimum)
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)
Black cottonwood (Populus balsamifera ssp. 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 walnut,
    California (female flowers) (Juglans californica var. californica)
    California (fruit) (Juglans californica var. californica)
    California (male flowers) (Juglans californica var. californica)
Black willow, Goodding's (Salix gooddingii)
Black-banded rabbitbrush (Ericameria paniculata)
Blackberry,
    California (Rubus ursinus)
    California, fruit (Rubus ursinus)
Blackbrush (Coleogyne ramosissima)
Bladder senna (Colutea arborescens)*
Bladderpod,
    [Common] (Peritoma arborea)
    King's (Physaria kingii ssp. kingii)
    San Bernardino Mountains (Physaria kingii ssp. bernardina)
Blazing star,
    Bushy (Mentzelia dispersa)
    Clustered (Mentzelia congesta)
    Giant (Mentzelia laevicaulis)
    Hairy (Mentzelia hirsutissima)
    Inyo (Mentzelia oreophila)
    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)
Blue dicks (Dichelostemma capitatum ssp. capitatum)
Blue flag, Western (Iris missouriensis)
Blue flax, Western (Linum lewisii var. lewisii)
Blue grama (Bouteloua gracilis)
Blue gum (Eucalyptus globulus)*
Blue larkspur (Delphinium parryi ssp. parryi)
Blue oak (Quercus douglasii)
Blue sage (Salvia dorrii var. dorrii)
Blue sage (Salvia dorrii var. pilosa)
Blue toadflax (Nuttallanthus texanus)
Blue violet (Viola adunca ssp. adunca)
Blue wildrye (Elymus glaucus ssp. glaucus)
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-eyed grass,
    [Common] (Sisyrinchium bellum)
    Idaho (Sisyrinchium idahoense var. occidentale)
Bluegrass,
    Bulbous (Poa bulbosa)*
    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-witch nightshade (Solanum umbelliferum)
Bluish spike-moss (Selaginella asprella)
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 var. occidentalis)
Boisduvalia, Smooth (Epilobium pygmaeum)
Bolander's monkeyflower (Mimulus bolanderi)
Bolander's woodland stars (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)
Boundary goldenbush (Ericameria brachylepis)
Bowlesia (Bowlesia incana)
Bownut cryptantha (Cryptantha cinerea var. 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)
Brake, Cliff (Pellaea truncata)
Branched hareleaf (Lagophylla ramosissima)
Branching phacelia,
    (Phacelia ramosissima var. latifolia) * These two vars. are Phacelia ramosissima in JM2
    (Phacelia ramossisima var. ramossisima) * These two vars. are Phacelia ramosissima in JM2
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 fleabane (Erigeron breweri var. breweri)
Brewer's lupine (Lupinus breweri var. breweri)
Brewer's monkeyflower (Mimulus 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)
    Little-leaved (Brickellia microphylla)
    Narrow-leaved (Brickellia oblongifolia var. linifolia)
    Nevin's (Brickellia nevinii)
    Shrubby (Brickellia frutescens)
    Spearleaf (Brickellia atractyloides var. arguta)
    Woolly (Brickellia incana)
Bright white (Prenanthella exigua)
Bristlecone pine (Pinus longaeva)
Bristly bird's beak (Cordylanthus rigidus ssp. rigidus)
Bristly bird's beak (Cordylanthus rigidus ssp. setigerus)
Bristly golden-aster (Heterotheca sessiliflora ssp. echioides)
Bristly langloisia (Langloisia setosissima ssp. setosissima)
Bristly matilija poppy (Romneya trichocalyx)
Bristly ox-tongue (Helminthotheca echioides)*
Bristly pectocarya (Pectocarya setosa)
Bristly-leaved rock-cress (Boechera rectissima)
Brittle fern (Cystopteris fragilis)
Brittle sandwort (Minuartia nuttallii var. gracilis)
Brittle spineflower (Chorizanthe brevicornu var. brevicornu)
Brittlebush (Encelia farinosa)
Broad-flowered gilia (Gilia latiflora ssp. latiflora)
Broad-fruited pectocarya (Pectocarya platycarpa)
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 crassifolius var. crassifolius)
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 carinatus var. carinatus)
    Hall's (Bromus hallii)
    Red (Bromus madritensis ssp. rubens)*
    Ripgut (Bromus diandrus)*
    Seaside (Bromus 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)
Broom-rape,
    California (Orobanche californica ssp. feudgei)
    Chaparral (Orobanche bulbosa)
    Clustered (Orobanche fasciculata)
    Cooper's (Orobanche cooperi)
    Naked (Orobanche uniflora)
    Parish's (Orobanche parishii ssp. parishii)
    Rock Creek (Orobanche valida ssp. valida)
    Short-lobed (Orobanche parishii ssp. brachyloba)
    Valley (Orobanche vallicola)
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)
    California, seed (Aesculus californica)
Buckhorn cholla (Cylindropuntia acanthocarpa var. coloradensis)
Buckwheat,
    Alpine suphur-flowered buckwheat (Eriogonum umbellatum var. minus)
    Angled-stem (Eriogonum angulosum)
    Ashy-leaf (Eriogonum cinereum)
    Birdnest (Eriogonum nidularium)
    California (Eriogonum fasciculatum var. fasciculatum)
    Conejo (Eriogonum crocatum)
    Cushenbury (Eriogonum ovalifolium var. vineum)
    Davidson's (Eriogonum davidsonii)
    Desert wild (Eriogonum fasciculatum var. polifolium)
    Dune (Eriogonum deserticola)
    East Mojave (Eriogonum fasciculatum var. flavoviride)
    Few-flowered naked (Eriogonum nudum var. pauciflorum)
    Flatcrown (Eriogonum deflexum)
    Flat-topped (Eriogonum plumatella)
    Gilman's (Eriogonum gilmanii)
    Heermann's (Eriogonum heermannii var. argense)
    Heermann's (Eriogonum heermannii var. floccosum)
    Island (Eriogonum grande var. grande)
    Johnston's (Eriogonum microthecum var. johnstonii)
    Kennedy's (Eriogonum kennedyi var. kennedyi)
    Knotty (Eriogonum wrightii var. nodosum)
    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)
    Pineland (Eriogonum molestum)
    Red-flowered (Eriogonum grande var. rubescens)
    Reveal's (Eriogonum contiguum)
    Rixford's (Eriogonum rixfordii)
    Rock (Eriogonum saxatile)
    San Jacinto (Eriogonum apiculatum)
    Santa Cruz Island (Eriogonum arborescens)
    Seacliff (Eriogonum parvifolium)
    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)
    Thomas' (Eriogonum thomasii)
    Thorne's (Eriogonum thornei)
    Varicolored (Eriogonum umbellatum var. versicolor)
    Weston's (Eriogonum nudum var. westonii)
    Wildrose Canyon (Eriogonum eremicola)
    Wright's (Eriogonum wrightii var. membranaceum)
    Wright's (Eriogonum wrightii var. subscaposum)
    Wright's (Eriogonum wrightii var. wrightii)
Budsage (Artemisia spinescens)
Buffalo-berry (Shepherdia argentea)
Bulbous bluegrass (Poa bulbosa)*
Bull mallow (Malva nicaeensis)*
Bull thistle (Cirsium vulgare)*
Bulrush,
    American (Schoenoplectus americanus)
    California (Schoenoplectus californicus)
    Marsh (Bolboschoenus maritimus ssp. paludosus)
    Panicled (Scirpus microcarpus)
Burbush, Holly-leaved (Ambrosia ilicifolia)
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)
    Woolly (Ambrosia eriocentra)
Bush anenome (Carpenteria californica)*
Bush chinquapin (Chrysolepis sempervirens)
Bush chinquapin seed pod (Chrysolepis sempervirens)
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)
    Fremont's (Malacothamnus fremontii)
    Indian Valley (Malacothamnus aboriginum)
    Pink-flowered (Malacothamnus marrubioides)
    San Clemente Island (Malacothamnus clementinus)
    Yellow-stemmed (Malacothamnus densiflorus)
Bush monkeyflower
    [Common] (Mimulus aurantiacus)}
    Island (Mimulus flemingii)
Bush muhly (Muhlenbergia porteri)
Bush poppy (Dendromecon rigida)
Bush sage,
    [Common] Mexican (Salvia leucantha)
    Purple Mexican (Salvia leucantha cv. "Midnight")
Bush senecio (Senecio flaccidus var. douglasii)
Bush spurge (Euphorbia characias)*
Bush sunflower (Encelia californica)
Bush-loving cryptantha (Cryptantha dumetorum)
Bushrue (Cneoridium dumosum)
Bushy blazing star (Mentzelia dispersa)
Bushy cryptantha (Cryptantha racemosa)
Buttercup,
    Bermuda (Oxalis pes-caprae)*
    California (Ranunculus californicus var. californicus)
    Delicate (Ranunculus hebecarpus)
    Eschscholtz's (Ranunculus eschscholtzii var. oxynotus)
    Rocky Mountain (Ranunculus cymbalaria var. saximontanus)
    Small water-plantain (Ranunculus alismifolius)
    Water (Ranunculus aquatilis var. capillaceus)
    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)