| Scientific Name | Most Common Name | |
| Acer macrophyllum | Maple, Big-leaf | |
| Acer negundo | Box Elder | |
| Achillea millefolium | Yarrow, Common | |
| Achyrachaena mollis | Blow-wives | |
| Acmispon americanus var. americanus | Lotus/Clover, Spanish | |
| Acmispon brachycarpus | Trefoil/Lotus, Short-podded/Hill | |
| Acmispon glaber var. glaber | Broom/Deerweed, California/Common | |
| Acmispon wrangelianus | Trefoil/Lotus, Chile | |
| Adenostoma fasciculatum | Chamise | |
| Adiantum jordanii | Fern, California Maiden-hair | |
| Aesculus californica | Buckeye, California | |
| Agoseris grandiflora | Dandelion, California | |
| Agoseris heterophylla | Agoseris, Annual | |
| Agrostis exarata | Bent Grass, Spike | |
| Agrostis hallii | Bent Grass, Hall's | |
| Ailanthus altissima | Tree of Heaven | |
| Aira caryophyllea | Hairgrass, Silver European | |
| Allium amplectens | Onion, Paper/ Narrow-leaf | |
| Allium serra | Onion, Jeweled | |
| Allium unifolium | Onion, One-leaf | |
| Alnus rhombifolia | Alder, White | |
| Amaranthus albus | Tumbleweed | |
| Amaranthus blitoides | Amaranth/Pigweed, Prostrate | |
| Amaryllis belladonna | Naked Lady | |
| Amsinckia intermedia | Fiddleneck, Common | |
| Amsinckia menziesii | Fiddleneck/Rancher's Fireweed | |
| Anagallis arvensis | Scarlet Pimpernel | |
| Anaphalis margaritacea | Everlasting, Pearly | |
| Anthemis arvensis | Corn Chamomile | |
| Anthemis cotula | Mayweed | |
| Anthriscus caucalis | Bur-chervil | |
| Antirrhinum kelloggii | Snapdragon, Kellogg's/Lax | |
| Antirrhinum vexillocalyculatum | Snapdragon, Brewer's/Sail-flower | |
| Aphanes occidentalis | Lady's Mantle, Western | |
| Aquilegia eximia | Columbine, Van Houtte's | |
| Arbutus menziesii | Madrone, Pacific | |
| Arctostaphylos glauca | Manzanita, Big-berry | |
| Artemisia californica | Sagebrush, California | |
| Artemisia douglasiana | Mugwort | |
| Asclepias californica | Milkweed, California/Round-hooded | |
| Asclepias fascicularis | Milkweed, Narrow-leaf | |
| Astragalus gambelianus | Locoweed, Dwarf | |
| Athysanus pusillus | Athysanus, Dwarf | |
| Avena barbata | Oat, Slender Wild | |
| Avena fatua | Oat, Wild | |
| Avena sativa | Oat, Cultivated | |
| Baccharis pilularis | Coyote Brush | |
| Baccharis salicifolia ssp. salicifolia | Mule Fat | |
| Barbarea orthoceras | Winter Cress, American | |
| Bellis perennis | Daisy, English | |
| Berberis aquifolium | Oregon Grape | |
| Bolboschoenus fluviatilis | Tule/Bulrush, River | |
| Bowlesia incana | Bowlesia, Hoary | |
| Brachypodium distachyon | Falsebrome, Purple | |
| Brassica juncea | Mustard, Indian | |
| Brassica nigra | Mustard, Black | |
| Briza minor | Grass, Little Rattlesnake | |
| Brodiaea coronaria | Brodiaea, Crown | |
| Brodiaea elegans ssp. elegans | Brodiaea, Harvest/Elegant | |
| Bromus berteroanus | Chess, Chilean | |
| Bromus carinatus | Brome, California | |
| Bromus diandrus | Grass, Ripgut | |
| Bromus hordeaceus | Chess, Soft | |
| Bromus laevipes | Brome, Chinook | |
| Bromus madritensis ssp. rubens | Brome Red | |
| Calandrinia ciliata | Red Maids | |
| Calochortus albus | Lily, White Globe | |
| Calochortus luteus | Lily, Yellow Mariposa | |
| Calochortus venustus | Lily, Butterfly/White Mariposa | |
| Calystegia purpurata ssp. purpurata | Morning-glory, Western/Chaparral | |
| Calystegia subacaulis ssp. subacaulis | Morning-glory, Hill | |
| Capsella bursa-pastoris | Shepherd's Purse | |
| Cardamine californica | Milk Maids | |
| Cardamine oligosperma | Cress, Bitter/Few-seeded | |
| Carduus pycnocephalus ssp. pycnocephalus | Thistle, Italian | |
| Carex serratodens | Sedge, Bifed | |
| Carex tumulicola | Sedge, Foothill | |
| Carthamus creticus | Thistle, Smooth Distaff | |
| Carthamus lanatus | Thistle, Woolly Distaff | |
| Castilleja affinis | Paintbrush, Indian | |
| Castilleja attenuata | Valley Tassels | |
| Castilleja densiflora | Owl's-clover | |
| Castilleja exserta | Owl's-clover, Purple | |
| Castilleja foliolosa | Paintbrush, Woolly Indian | |
| Castilleja subinclusa ssp. franciscana | Paintbrush, Franciscan | |
| Caulanthus lasiophyllus | Mustard, California | |
| Ceanothus cuneatus var. cuneatus | Buck Brush | |
| Ceanothus papillosus | Ceanothus, Wartleaf | |
| Centaurea calcitrapa | Thistle, Purple Star- | |
| Centaurea melitensis | Tocalote | |
| Centaurea solstitialis | Thistle, Yellow Star- | |
| Centromadia fitchii | Tarweed/Spikeweed, Fitch's | |
| Centromadia pungens ssp. pungens | Tarweed/Spikeweed, Common | |
| Cerastium glomeratum | Chickweed, Mouse-ear | |
| Cercocarpus betuloides var. betuloides | Mountain-mahogany, Birch-leaf | |
| Chenopodium album | Pigweed/Lambs-quarters | |
| Chenopodium californicum | Goosefoot, California | |
| Chlorogalum pomeridianum | Soap Plant/Amole | |
| Cirsium occidentale var. venustum | Thistle, Venus | |
| Cirsium vulgare | Thistle, Bull | |
| Clarkia amoena | Clarkia, Farewell-to-spring | |
| Clarkia purpurea ssp. quadrivulnera | Four-spot | |
| Clarkia purpurea ssp. viminea | Clarkia, Purple/Large | |
| Clarkia rubicunda | Clarkia, Ruby Chalice | |
| Clarkia unguiculata | Clarkia, Elegant | |
| Claytonia exigua ssp. exigua | Montia, Common | |
| Claytonia gypsophiloides | Claytonia/Montia, Spring Beauty/Coast Range | |
| Claytonia perfoliata ssp. perfoliata | Miner's Lettuce ssp. perfoliata | |
| Clematis lasiantha | Pipestems | |
| Clinopodium douglasii | Yerba Buena | |
| Collinsia heterophylla | Chinese Houses | |
| Collinsia multicolor | Collinsia, San Francisco | |
| Collinsia sparsiflora var. collina | Collinsia, Hillside/Blue-eyed Mary | |
| Conium maculatum | Poison Hemlock | |
| Corallorhiza striata | Coralroot, Striped | |
| Cordylanthus pilosus ssp. pilosus | Bird's Beak, Hairy | |
| Cordylanthus rigidus | Bird's-beak, Rigid | |
| Cornus glabrata | Dogwood, Brown | |
| Cortaderia selloana | Pampas Grass, Uruguayan | |
| Crassula connata | Pygmy-weed | |
| Crepis capillaris | Hawksbeard, Smooth | |
| Crepis vesicaria ssp. taraxacifolia | Hawksbeard, Beaked | |
| Croton setigerus | Mullein, Turkey | |
| Crypsis schoenoides | Grass, Swamp | |
| Cryptantha flaccida | Cryptantha, Beaked/Flaccid | |
| Cryptantha muricata | Popcornflower, Prickly | |
| Cupressus sempervirens | Cypress, Italian | |
| Cynoglossum grande | Hound's Tongue, Pacific/Western | |
| Cynosurus echinatus | Grass, Hedgehog Dogtail | |
| Cyperus eragrostis | Nutsedge/Cyperus, Tall | |
| Datura stramonium | Datura/Jimson Weed | |
| Daucus pusillus | Rattlesnake Weed | |
| Delphinium patens ssp. patens | Larkspur, Spreading/Zigzag | |
| Deschampsia elongata | Hairgrass, Slender | |
| Desmazeria rigida | Ferngrass | |
| Dichelostemma capitatum ssp. capitatum | Blue Dicks ssp. capitatum | |
| Dichelostemma congestum | Ookow | |
| Dipsacus sativus | Teasel, Fuller's | |
| Dittrichia graveolens | Stinkwort | |
| Dodecatheon clevelandii ssp. sanctarum | Shooting Star, Padre's ssp. sanctarum | |
| Dodecatheon hendersonii | Shooting Star/Mosquito Bills | |
| Drymocallis glandulosa | Cinquefoil, Common/Sticky | |
| Dudleya abramsii ssp. setchellii | Dudleya, Santa Clara Valley | |
| Dudleya cymosa ssp. cymosa | Dudleya, Canyon/Spreading | |
| Eleocharis acicularis | Spikerush, Needle | |
| Elymus glaucus ssp. glaucus | Grass, Blue Wildrye ssp. glaucus | |
| Elymus multisetus | Grass, Big Squirreltail | |
| Elymus triticoides | Ryegrass, Alkali | |
| Emmenanthe penduliflora | Whispering Bells | |
| Epilobium brachycarpum | Willow Herb, Panicled | |
| Epilobium canum | Fuchsia, California | |
| Epilobium densiflorum | Boisduvalia, Dense-flowered | |
| Epilobium minutum | Willow Herb, Minute | |
| Eriodictyon californicum | Yerba Santa, California | |
| Eriogonum luteolum var. luteolum | Buckwheat, Wicker/Golden | |
| Eriogonum nudum | Buckwheat, Nude | |
| Eriophyllum confertiflorum var. confertiflorum | Golden-yarrow | |
| Erodium botrys | Storksbill/Filaree, Long-beaked | |
| Erodium cicutarium | Storksbill/Filaree, Red-stemmed | |
| Erodium moschatum | Storksbill/Filaree, White-stemmed | |
| Eryngium aristulatum | Eryngo, Jepson's | |
| Eschscholzia californica | Poppy, California | |
| Eucalyptus globulus | Gum, Blue | |
| Euphorbia spathulata | Spurge, Reticulate Seeded/Warty | |
| Eurybia radulina | Aster, Rough-leaved | |
| Euthamia occidentalis | Goldenrod, Western | |
| Festuca bromoides | Fescue, European Foxtail/Six-weeks | |
| Festuca californica | Fescue, California | |
| Festuca microstachys | Fescue, Small | |
| Festuca myuros | Fescue, Foxtail | |
| Festuca perennis | Ryegrass | |
| Frangula californica ssp. californica | Coffeeberry, California ssp. californica | |
| Fritillaria affinis | Lily, Checker | |
| Fritillaria liliacea | Fritillary, Fragrant | |
| Galium andrewsii | Bedstraw, Phlox-leaved | |
| Galium aparine | Goose Grass | |
| Galium murale | Bedstraw, Tiny/Yellow Wall | |
| Galium porrigens var. porrigens | Bedstraw, Climbing/Graceful | |
| Gamochaeta ustulata | Cudweed, Purple | |
| Garrya elliptica | Silk Tassel, Coast | |
| Gastridium phleoides | Grass, Nit | |
| Genista monspessulana | Broom, French | |
| Geranium dissectum | Geranium, Cut-leaved | |
| Geranium molle | Geranium, Cranesbill | |
| Gilia achilleifolia ssp. multicaulis | Gilia, Many-stemmed/California | |
| Gilia tricolor | Gilia, Bird's Eyes/Tricolor | |
| Grindelia camporum | Gumweed, Common/Great Valley | |
| Hainardia cylindrica | Grass, Thin Tail | |
| Helenium puberulum | Sneezeweed | |
| Helianthella castanea | Helianthella, Diablo | |
| Heliotropium curassavicum var. oculatum | Heliotrope, Salt/Seaside | |
| Hemizonia congesta ssp. luzulifolia | Tarweed, Hayfield ssp. luzulifolia | |
| Heracleum maximum | Cowparsnip, Common | |
| Hesperevax sparsiflora | Evax, Erect | |
| Hesperocnide tenella | Nettle, Western | |
| Hesperolinon micranthum | Flax, Common/Small-flowered Dwarf | |
| Heteromeles arbutifolia | Toyon | |
| Heterotheca sessiliflora ssp. echioides | Goldenaster, Bristly | |
| Hirschfeldia incana | Hoary-mustard, Mediterranean | |
| Hoita macrostachya | Leather-root | |
| Hoita strobilina | Hoita/Psoralea, Loma Prieta | |
| Holodiscus discolor var. discolor | Oceanspray | |
| Hordeum brachyantherum ssp. californicum | Barley, California Meadow | |
| Hordeum marinum ssp. gussoneanum | Barley, Mediterranean | |
| Hordeum murinum ssp. leporinum | Foxtail, Farmer's | |
| Hordeum vulgare | Barley, Common | |
| Horkelia californica var. frondosa | Horkelia, California ssp. frondosa | |
| Hypochaeris glabra | Cat's-ear, Smooth | |
| Hypochaeris radicata | Cat's-ear, Rough/Hairy | |
| Iris douglasiana | Iris, Douglas' | |
| Iris macrosiphon | Iris, Ground/Bowltube | |
| Juncus bufonius | Rush, Toad | |
| Juncus effusus ssp. pacificus | Rush, Pacific Bog | |
| Juncus patens | Rush, Spreading/Common | |
| Juncus xiphioides | Rush, Iris-leaved | |
| Koeleria macrantha | Junegrass | |
| Lactuca saligna | Lettuce, Willow | |
| Lactuca serriola | Lettuce, Prickly/Wild | |
| Lactuca virosa | Lettuce, Bitter | |
| Lagophylla ramosissima | Hareleaf, Common | |
| Lamarckia aurea | Grass, Goldentop | |
| Lamium amplexicaule | Henbit/Deadnettle | |
| Lasthenia californica | Goldfields, California/Common | |
| Lasthenia maritima | Goldfields, Maritime | |
| Lathyrus latifolius | Pea, Perennial Sweet | |
| Lathyrus vestitus var. vestitus | Pea, Hillside/Common Pacific | |
| Layia gaillardioides | Layia, Woodland | |
| Lepechinia calycina | Pitcher Sage/Woodbalm | |
| Lepidium draba | Hoary Cress, Heart-podded | |
| Lepidium nitidum | Peppergrass, Common/Shining | |
| Lepidium strictum | Peppergrass, Prostrate/Wayside | |
| Leptosiphon ambiguus | Linanthus, Serpentine | |
| Leptosiphon androsaceus | Linanthus, Common/Showy | |
| Leptosiphon bicolor | Linanthus, Bicolor | |
| Leptosiphon ciliatus | Linanthus, Whisker Brush | |
| Leptosiphon liniflorus | Linanthus, Flax-flowered | |
| Leptosiphon parviflorus | Linanthus, Common/Variable/Small-flowered | |
| Lessingia micradenia var. glabrata | Lessingia, Smooth | |
| Linanthus dichotomus | Evening Snow | |
| Lithophragma affine | Star, Woodland/Common | |
| Lithophragma heterophyllum | Star, Hillside | |
| Logfia filaginoides | Filago/Cottonrose, California | |
| Logfia gallica | Filago/Cottonrose, Narrow-leaved | |
| Lomatium dasycarpum ssp. dasycarpum | Lomatium, Woolly-fruited | |
| Lomatium macrocarpum | Lomatium, Large-fruited | |
| Lomatium utriculatum | Lomatium, Common/Bladder Parsnip | |
| Lonicera hispidula | Honeysuckle, California/Hairy | |
| Lupinus albifrons | Lupine, Silver/Silver Bush | |
| Lupinus bicolor | Lupine, Annual/Bicolored/Miniature | |
| Lupinus latifolius var. latifolius | Lupine, Broadleaf | |
| Lupinus microcarpus var. densiflorus | Lupine, Chick var. densiflorus | |
| Lupinus nanus | Lupine, Sky | |
| Lupinus succulentus | Lupine, Arroyo/Succulent | |
| Luzula comosa | Rush, Common/Pacific/Hairy Wood | |
| Lythrum hyssopifolia | Loosestrife, Hyssop | |
| Madia elegans | Madia/Tarweed, Common | |
| Madia exigua | Madia/Tarweed, Threadstem/Small | |
| Madia gracilis | Madia/Tarweed, Gumweed/Slender | |
| Madia sativa | Tarweed, Coast/Common | |
| Maianthemum stellatum | Solomon's Seal, False/Slim | |
| Malacothamnus hallii | Bush Mallow, Hall's | |
| Malva nicaeensis | Mallow, Bull | |
| Malva parviflora | Cheeseweed | |
| Marah fabacea | Man-root, California | |
| Marrubium vulgare | Horehound, Common | |
| Matricaria discoidea | Pineapple Weed | |
| Medicago orbicularis | Buttonclover | |
| Medicago polymorpha | Burclover, California | |
| Melica californica | Melic, California | |
| Melica imperfecta | Melic, Small-flowered | |
| Melica torreyana | Melic, Torrey's | |
| Melilotus indicus | Sourclover | |
| Mentzelia lindleyi | Blazing Star, Lindley's | |
| Micranthes californica | Saxifrage, California | |
| Micropus californicus var. californicus | Cottonweed, Slender/Hairy var. californicus | |
| Microseris douglasii | Microseris, Douglas's | |
| Microseris laciniata | Scorzonella/Microseris, Cut-leaved | |
| Microsteris gracilis | Phlox, Slender/Annual | |
| Mimulus aurantiacus | Monkeyflower, Sticky/Bush/Island | |
| Mimulus guttatus | Monkeyflower, Large/Yellow/Seep | |
| Monardella douglasii | Monardella, Perforated | |
| Monardella villosa ssp. franciscana | Coyote-mint, San Francisco | |
| Monardella villosa ssp. villosa | Coyote-mint, ssp. villosa | |
| Monolopia gracilens | Monolopia, Woodland | |
| Monolopia major | Monolopia, Cupped | |
| Nasturtium officinale | Cress, Water | |
| Navarretia atractyloides | Navarretia, Holly-leaf | |
| Navarretia heterodoxa | Navarretia, Calistoga | |
| Navarretia squarrosa | Skunkweed | |
| Nemophila heterophylla | Nemophila, Canyon/White/Variable-leaved | |
| Nemophila menziesii var. atomaria | Baby Blue-eyes var. atomaria | |
| Nemophila parviflora var. parviflora | Nemophila, Woodland | |
| Nicotiana glauca | Tree Tobacco | |
| Nuttallanthus texanus | Toadflax, Blue | |
| Oemleria cerasiformis | Oso Berry | |
| Olea europaea | Olive | |
| Opuntia xoccidentalis | Cactus, Western Prickly Pear | |
| Orobanche fasciculata | Broom-rape, Clustered | |
| Osmorhiza berteroi | Sweet Cicely, Wood | |
| Papaver heterophyllum | Poppy, Wind | |
| Parapholis incurva | Sickle Grass | |
| Pedicularis densiflora | Indian Warrior | |
| Pellaea andromedifolia | Fern, Coffee | |
| Pellaea mucronata var. mucronata | Fern, Bird's-foot var. mucronata | |
| Pentagramma triangularis ssp. triangularis | Fern, Gold-back ssp. triangularis | |
| Perideridia kelloggii | Yampah, Kellogg's | |
| Phacelia californica | Phacelia, California | |
| Phacelia distans | Phacelia, Common | |
| Phacelia imbricata ssp. imbricata | Phacelia, Imbricate ssp. imbricata | |
| Phalaris aquatica | Grass, Harding | |
| Phalaris californica | Canary Grass, California | |
| Pholistoma auritum var. auritum | Fiesta Flower, Blue/Common | |
| Pholistoma membranaceum | Fiesta Flower, White | |
| Phoradendron serotinum ssp. tomentosum | Mistletoe, Oak | |
| Phragmites australis | Reed, Common | |
| Pinus pinea | Pine, Italian Stone/Umbrella | |
| Piperia elegans | Piperia/Rein Orchid, Elegant/Hillside | |
| Piperia unalascensis | Piperia/Rein Orchid, Alaska | |
| Plagiobothrys canescens | Popcornflower, Valley/Grey | |
| Plagiobothrys glaber | Popcornflower, Hairless | |
| Plagiobothrys nothofulvus | Popcornflower | |
| Plantago erecta | Plantain, California | |
| Plantago lanceolata | Plantain, English | |
| Platanus racemosa | Sycamore, Western/California | |
| Platystemon californicus | Cream Cups | |
| Plectritis ciliosa | Plectritis, Long-spurred | |
| Plectritis congesta | Plectritis/Sea Blush, Short-spurred | |
| Poa annua | Bluegrass, Annual | |
| Poa howellii | Bluegrass, Howell's | |
| Poa secunda ssp. secunda | Bluegrass, One-sided | |
| Pogogyne serpylloides | Pogogyne, Thyme-leaved | |
| Polycarpon tetraphyllum var. tetraphyllum | Allseed, Four-leaved | |
| Polygonum aviculare ssp. depressum | Knotweed, Common | |
| Polypodium californicum | Fern, California Polypody | |
| Polypodium glycyrrhiza | Fern, Licorice | |
| Polypogon monspeliensis | Beard Grass, Annual/Rabbitfoot | |
| Polypogon viridis | Bent Grass, Water | |
| Prosartes hookeri | Fairy Bell, Hooker's | |
| Prunus emarginata | Cherry, Bitter | |
| Prunus ilicifolia | Cherry, Holly-leafed | |
| Prunus virginiana var. demissa | Choke-cherry, Western | |
| Pseudognaphalium californicum | Cudweed, California | |
| Pseudognaphalium luteoalbum | Cudweed, Common/Weedy | |
| Pseudognaphalium stramineum | Cudweed, Chilean/Cotton-batting Plant | |
| Psilocarphus brevissimus var. brevissimus | Woolly-heads/Marbles, Dwarf/Short | |
| Psilocarphus tenellus | Woolly-heads/Marbles, Slender | |
| Pteridium aquilinum var. pubescens | Fern, Bracken | |
| Pterostegia drymarioides | Pterostegia, Woodland | |
| Quercus agrifolia var. agrifolia | Oak, Coast Live | |
| Quercus berberidifolia | Oak, Scrub | |
| Quercus douglasii | Oak, Blue | |
| Quercus durata var. durata | Oak, Leather | |
| Quercus kelloggii | Oak, California Black | |
| Quercus lobata | Oak, Valley | |
| Quercus wislizeni | Oak, Interior Live | |
| Rafinesquia californica | Chicory, California | |
| Ranunculus aquatilis var. diffusus | Buttercup, Water var. capillaceus | |
| Ranunculus californicus | Buttercup, California | |
| Ranunculus hebecarpus | Buttercup, Pubescent-fruited | |
| Raphanus sativus | Radish, Cultivated/Wild | |
| Rhamnus crocea | Redberry, Spiny | |
| Rhamnus ilicifolia | Redberry, Holly-leaf | |
| Ribes californicum var. californicum | Gooseberry, Hillside var. californicum | |
| Ribes malvaceum var. malvaceum | Currant, Chaparral var. malvaceum | |
| Ribes menziesii | Gooseberry, Canyon | |
| Rigiopappus leptocladus | Rigiopappus/Wire-weed | |
| Robinia pseudoacacia | Locust, Black | |
| Rosa californica | Rose, California | |
| Rosa gymnocarpa | Rose, Wood | |
| Rosa spithamea | Rose, Ground | |
| Rubus armeniacus | Blackberry, Himalayan | |
| Rubus ursinus | Blackberry, California | |
| Rumex acetosella | Sheep Sorrel, Common | |
| Rumex conglomeratus | Dock, Clustered/Green | |
| Rumex crispus | Dock, Curly | |
| Rupertia physodes | Tea, California | |
| Salix laevigata | Willow, Red | |
| Salix lasiolepis | Willow, Arroyo | |
| Salsola tragus | Thistle, Russian | |
| Salvia columbariae | Chia | |
| Salvia mellifera | Sage, Black | |
| Sambucus nigra ssp. caerulea | Elderberry, Blue | |
| Sanicula arctopoides | Footsteps of Spring | |
| Sanicula bipinnata | Sanicle, Poison | |
| Sanicula bipinnatifida | Sanicle, Purple | |
| Sanicula crassicaulis | Sanicle, Pacific | |
| Scandix pecten-veneris | Venus's/Shepherd's Needle | |
| Schinus molle | Pepper Tree, Peruvian | |
| Scirpus microcarpus | Bulrush, Panicled/Small-fruited | |
| Scrophularia californica | Bee-plant, California | |
| Scutellaria tuberosa | Skullcap, Dannie's | |
| Selaginella bigelovii | Spike-moss, Bigelow's | |
| Senecio vulgaris | Groundsel/Old Man of Spring, Common | |
| Sherardia arvensis | Madder, Blue Field | |
| Sidalcea malviflora | Checker Mallow/Bloom | |
| Silene gallica | Pink, Windmill | |
| Silybum marianum | Thistle, Milk | |
| Sinapis arvensis | Charlock | |
| Sisymbrium irio | London Rocket | |
| Sisymbrium officinale | Mustard, Hedge | |
| Sisyrinchium bellum | Blue-eyed-grass | |
| Solanum americanum | Nightshade, American/Small-flowered | |
| Solanum umbelliferum | Nightshade, Blue Witch | |
| Sonchus asper ssp. asper | Thistle, Prickly Sow | |
| Sonchus oleraceus | Thistle, Common Sow | |
| Spartium junceum | Broom, Spanish | |
| Spergularia rubra | Sand-spurrey, Purple | |
| Stachys bullata | Hedge Nettle, California | |
| Stachys rigida | Hedge Nettle, Rigid | |
| Stellaria media | Chickweed, Common | |
| Stellaria nitens | Chickweed, Shining | |
| Stephanomeria virgata | Stephanomeria, Tall | |
| Stipa lepida | Needlegrass, Foothill | |
| Stipa miliacea var. miliacea | Grass, Smilo | |
| Stipa pulchra | Needlegrass, Purple | |
| Streptanthus glandulosus ssp. glandulosus | Jewelflower, Bristly/Common | |
| Stuckenia pectinata | Pondweed, Fennel-leaf | |
| Symphoricarpos albus var. laevigatus | Snowberry, Common/Upright | |
| Symphoricarpos mollis | Snowberry, Creeping/Trailing | |
| Symphyotrichum chilense | Aster, California | |
| Tauschia hartwegii | Tauschia, Hartweg's | |
| Tetrapteron graciliflorum | Sun Cup, Hill | |
| Thalictrum fendleri var. polycarpum | Meadow-rue, Fendler's var. polycarpum | |
| Thysanocarpus curvipes | Fringepod, Common/Hairy | |
| Thysanocarpus laciniatus | Fringepod, Narrow-leaved/Crenate | |
| Torilis arvensis | Hedge Parsley, Field/Spreading | |
| Torilis nodosa | Hedge Parsley, Knotted | |
| Toxicodendron diversilobum | Poison Oak, Western | |
| Toxicoscordion fremontii | Lily/Death Camas, Fremont's Star | |
| Tragopogon porrifolius | Salsify/Oyster Plant | |
| Tribulus terrestris | Puncture-vine | |
| Trichostema lanceolatum | Vinegar Weed | |
| Trientalis latifolia | Starflower, Western/Pacific | |
| Trifolium albopurpureum | Clover, Indian | |
| Trifolium bifidum var. decipiens | Clover, Deceptive | |
| Trifolium depauperatum var. truncatum | Clover, Dwarf Sack | |
| Trifolium dichotomum | Clover, Branched Indian | |
| Trifolium fucatum | Clover, Sour/Bull | |
| Trifolium gracilentum | Clover, Pin-point var. gracilentum | |
| Trifolium hirtum | Clover, Rose | |
| Trifolium incarnatum | Clover, Crimson | |
| Trifolium microcephalum | Clover, Small-headed/Hairy/Maiden | |
| Trifolium microdon | Clover, Valparaiso/Thimble | |
| Trifolium subterraneum | Clover, Subterranean | |
| Trifolium willdenovii | Clover, Tomcat | |
| Trillium chloropetalum | Trillium, Giant | |
| Triphysaria pusilla | Orthocarpus, Dwarf | |
| Trisetum canescens | Trisetum/Oatgrass, Nodding/Tall | |
| Trisetum cernuum | Trisetum/Oatgrass, Nodding | |
| Triteleia hyacinthina | Brodiaea, White | |
| Triteleia laxa | Ithuriel's Spear | |
| Triticum aestivum | Wheat | |
| Tropidocarpum gracile | Dobie Pod | |
| Turritis glabra | Rock Cress, Tower | |
| Typha angustifolia | Cattail, Narrow-leaved | |
| Umbellularia californica | California Bay | |
| Urtica dioica ssp. holosericea | Nettle, Hoary | |
| Urtica urens | Nettle, Dwarf | |
| Verbena lasiostachys var. scabrida | Vervain, Robust | |
| Veronica arvensis | Speedwell, Corn | |
| Veronica persica | Speedwell, Persian | |
| Vicia americana ssp. americana | Vetch, American | |
| Vicia benghalensis | Vetch, Purple | |
| Vicia gigantea | Vetch, Giant | |
| Vicia sativa ssp. nigra | Vetch, Narrow-leaved | |
| Vicia sativa ssp. sativa | Vetch, Common/Spring | |
| Vicia villosa ssp. varia | Vetch, Thick-fruited | |
| Viola ocellata | Violet, Two-eyed/Heart's Ease/Western | |
| Viola pedunculata | Violet, California Golden/Johnny-jump-up | |
| Woodwardia fimbriata | Fern, Giant Chain | |
| Wyethia glabra | Mule Ears, Coast Range/Smooth | |
| Xanthium spinosum | Cocklebur, Spiny | |
| Xanthium strumarium | Cocklebur | |
| Yabea microcarpa | Hedge Parsley, California | |