| A'ali'i | Dodonaea viscosa |
| Abutilon, Hoary | Abutilon incanum |
| Adam's Needle | Yucca filamentosa |
| Agarita | Berberis trifoliolata |
| Agave, Chisos Mountain | Agave x glomeruliflora |
| Agave, Desert | Agave deserti |
| Ageratum, Hardy | Conoclinium coelestinum |
| Agoseris, Pale | Agoseris glauca |
| 'aiakanene | Coprosma ernodeoides |
| Air Plant | Kalanchoe pinnata |
| Alaska Cotton | Eriophorum scheuchzeri |
| Alder, Red | Alnus rubra |
| Alder, Smooth | Alnus serrulata |
| Alder, speckled | Alnus incana ssp. Rugosa |
| Alligator Flag, Bent | Thalia geniculata |
| Alumroot | Heuchera richardsonii |
| Alumroot, Pink | Heuchera rubescens |
| American Threefold | Trixis californica |
| American Vetch | Vicia americana |
| Anacahuita | Cordia boissieri |
| Anacua | Ehretia anacua |
| Andrew's Ladyslipper | Cypripedium x andrewsii |
| Anemone, Carolina | Anemone caroliniana |
| Anemone, Desert | Anemone tuberosa |
| Anemone, Meadow | Anemone canadensis |
| Anemone, Narcissus-flowered | Anemone narcissiflora |
| Anemone, Northern | Anemone parviflora |
| Anemone, Rue | Thalictrum thalictroides |
| Anemone, Small-flowered | Anemone parviflora |
| Anemone, Tall | Anemone virginiana |
| Anemone, Two-Flower | Anemone edwardsiana var. petraea |
| Anemone, Wood | Anemone quinquefolia |
| Anemone, Yellow | Anemone richardsonii |
| Angelica, Great | Angelica atropurpurea |
| Angel's Trumpet | Brugmansia x candida (aurea x versicolor) |
| Apache Plume | Fallugia paradoxa |
| Arbor Vitae | Thuja occidentalis |
| Arbutus, Trailing | Epigaea repens |
| Arnica, Broadleaf | Arnica latifolia |
| Arnica, Frigid | Arnica griscomii |
| Arnica, Hairy | Arnica mollis |
| Arnica, Heart-leaved | Arnica cordifolia |
| Arnica, Mountain | Arnica latifolia |
| Arnica, Snow | Arnica griscomii |
| Arrow Grass | Scheuchzeria palustris |
| Arrowhead, Bull-tongue | Sagittaria lancifolia |
| Arrowhead, Common | Sagittaria latifolia |
| Arrow-weed | Pluchea sericea |
| Arrowwood, Downey | Viburnum rafinesquianum |
| Ash, California | Fraxinus dipetala |
| Ash, Wafer | Ptelea trifoliata |
| Aspen, Quaking | Populus tremuloides |
| Aster, Arctic | Eurybia sibirica |
| Aster, Aromatic | Symphyotrichum oblongifolium |
| Aster, Bog | Oclemena nemoralis |
| Aster, Bristly | Symphyotrichum puniceum |
| Aster, Climbing | Ampelaster carolinianus |
| Aster, Common Blue Wood | Symphyotrichum cordifolium |
| Aster, Drummond's | Symphyotrichum drummondii |
| Aster, Flat-topped | Doellingeria umbellata |
| Aster, Flax-leaved | Ionactis linariifolia |
| Aster, Hairy | Symphyotrichum pilosum |
| Aster, Heath | Symphyotrichum ericoides |
| Aster, Mohave Woody | Xylorhiza tortifolia |
| Aster, New England | Symphyotrichum novae-angliae |
| Aster, Orcutt's | Xylorhiza orcuttii |
| Aster, Panicled | Symphyotrichum lanceolatum |
| Aster, Purple-stemmed | Symphyotrichum puniceum |
| Aster, Shining | Symphyotrichum firmum |
| Aster, Short's | Symphyotrichum shortii |
| Aster, Siberian | Eurybia sibirica |
| Aster, Side-flowering | Symphyotrichum lateriflorum |
| Aster, Silky | Symphyotrichum sericeum |
| Aster, Skyblue | Symphyotrichum oolentangiense |
| Aster, Smooth Blue | Symphyotrichum laeve |
| Aster, Stiff | Solidago ptarmicoides |
| Aster, Swamp | Symphyotrichum puniceum |
| Aster, Western Showy | Eurybia conspicua |
| Aster, Western Silver | Symphyotrichum sericeum |
| Aster, Whorled Wood | Oclemena acuminata |
| Aster, Willow | Symphyotrichum praealtum |
| Aster, Yellow Stiff | Solidago x lutescens |
| Aunt Lucy | Ellisia nyctelea |
| Avalanche-Lily, White | Erythronium montanum |
| Aven, Yellow | Geum aleppicum |
| Avens, alpine | Geum rossii |
| Avens, Water | Geum rivale |
| Avens, White | Geum canadense |
| Azalea, Alpine | Kalmia procumbens |
| Azalea, Cascade | Rhododendron albiflorum |
| Azalea, Western | Rhododendron occidentale |
| Baby Blue-eyes | Nemophila menziesii |
| Babybonnets, Rosary | Coursetia glandulosa |
| Baby-innocence, Greater | Tonella floribunda |
| Bald Cypress | Taxodium distichum |
| Balsam, old-field | Pseudognaphalium obtusifolium |
| Balsamroot, Arrow-leaved | Balsamorhiza sagittata |
| Banana | Musa sp. |
| Baneberry, Red | Actaea rubra |
| Baneberry, White | Actaea pachypoda |
| Barberry, Holly-leaved | Berberis aquifolium |
| Barberry, Japanese | Berberis thunbergii |
| Barberry, Red | Berberis haematocarpa |
| Barnyard-grass | Echinochloa walteri |
| Barometer Bush, Texas | Leucophyllum frutescens |
| Basin Yellow Cryptantha | Cryptantha confertiflora |
| Bay Hops | Ipomoea pes-caprae |
| Bay, California | Umbellularia californica |
| Beak Rush, Hair | Rhynchospora capillacea |
| Beak Rush, White | Rhynchospora alba |
| Bearberry | Arctostaphylos uva-ursa |
| Beard-tongue, Chaparral | Keckiella antirrhinoides |
| Beard-tongue, Foxglove | Penstemon digitalis |
| Beardtongue, Hairy | Penstemon hirsutus |
| Beardtongue, Low | Penstemon humilis |
| Beardtongue, Minidoka | Penstemon perpulcher |
| Beard-tongue, Pale | Penstemon pallidus |
| Bearflower | Boykinia richardsonii |
| Beargrass | Xerophyllum tenax |
| Bedstraw, bluntleaf | Galium obtusum |
| Bedstraw, Bog | Galium labradoricum |
| Bedstraw, Common Marsh | Galium palustre |
| Bedstraw, Northern | Galium boreale |
| Bedstraw, Rough | Galium asprellum |
| Bee Balm, Spotted | Monarda punctata |
| Beeblossom, Longflower | Oenothera filiformis |
| Beech Drops | Epifagus virginiana |
| Beech, American | Fagus grandifolia |
| Beech, Blue | Carpinus caroliniana |
| Beggarticks, Hawaii | Bidens hawaiensis |
| Bellflower, European | Campanula rapunculoides |
| Bellflower, Marsh | Campanula aparinoides |
| Bellflower, Parry's | Campanula parryi |
| Bellflower, Tall | Campanula americana |
| Bellheather, Alaska | Harrimanella stelleriana |
| Bellwort | Uvularia grandiflora |
| Bellwort, Perfoliate | Uvularia perfoliata |
| Bellwort, sessileleaf | Uvularia sessilifolia |
| Bergamot, Wild | Monarda fistulosa |
| Be-Still Tree | Cascabela thevetia |
| Betony, Fen | Pedicularis lanceolata |
| Betony, Wood | Pedicularis canadensis |
| Bindweed, Fringed | Fallopia cilinodis |
| Bindweed, Hedge False | Calystegia sepium |
| Bindweed, Low False | Calystegia spithamaea |
| Bindweed. Field | Convolvulus arvensis |
| Birch, Bog | Betula pumila |
| Birch, Paper | Betula papyrifera |
| Birch, Yellow | Betula alleghaniensis |
| Bird's Eyes | Gilia tricolor |
| Biscuitroot, Fernleaf | Lomatium dissectum |
| Biscuitroot, Idaho | Lomatium idahoense |
| Bistort, Alpine | Bistorta vivipara |
| Bistort, American | Bistorta bistortoides |
| Bistort, Meadow | Bistorta officinalis |
| Bitter Melon | Momordica charantia |
| Bitterroot | Lewisia rediviva |
| Bittersweet, Oriental | Celastrus orbiculatus |
| Black Haw | Viburnum prunifolium |
| Blackberry, Highbush | Rubus allegheniensis |
| Black-Eyed Susan | Rudbeckia hirta |
| Black-eyed Susan, Sweet | Rudbeckia subtomentosa |
| Blackfoot, Hoary | Melampodium cinereum |
| Blackfoot, Plains | Melampodium leucanthum |
| Bladdernut, American | Staphylea trifolia |
| Bladderpod | Peritoma isomeris |
| Bladderpod, Fendler's | Physaria fendleri |
| Bladderpod, Rose | Physaria purpurea |
| Bladdersage, Mexican | Scutellaria mexicana |
| Bladderwort, Flat-Leaved | Utricularia intermedia |
| Bladderwort, Great | Utricularia macrorhiza |
| Bladderwort, Horned | Utricularia cornuta |
| Bladderwort, Humped | Utricularia gibba |
| Bladderwort, Small | Utricularia minor |
| Blazing Star, Button | Liatris aspera |
| Blazing Star, Cylindrical | Liatris cylindracea |
| Blazing Star, Marsh | Liatris spicata |
| Blazing Star, Sand | Mentzelia involucrata |
| Blazing Star, Spinyhair | Mentzelia tricuspis |
| Blazing Star, White-Stemmed | Mentzelia albicaulis |
| Blazingstar, Prairie | Liatris pycnostachya |
| Bleed Heart | Lamprocapnos spectabilis |
| Bleeding Heart, Pacific | Dicentra formosa |
| Bloodroot | Sanguinaria canadensis |
| Blue Flax | Linum lewisii |
| Blue Hearts | Buchnera americana |
| Bluebead Lily | Clintonia borealis |
| Bluebells, Northern | Mertensia paniculata var. borealis |
| Bluebells, Northern | Mertensia paniculata var. paniculata |
| Bluebells, Oblong-leaf | Mertensia oblongifolia |
| Bluebells, Small | Mertensia longiflora |
| Bluebells, Tall Fringed | Mertensia ciliata |
| Bluebells, Virginia | Mertensia virginica |
| Blueberry, Alaska | Vaccinium alaskaense |
| Blueberry, Bog | Vaccinium uliginosum |
| Blueberry, Early Low-bush | Vaccinium pallidum |
| Blueberry, Highbush | Vaccinium corymbosum |
| Blueberry, Lowbush | Vaccinium angustifolium |
| Blueberry, Velvetleaf | Vaccinium myrtilloides |
| Bluebonnet, Big Bend | Lupinus havardii |
| Blue-eyed Grass | Sisyrinchium albidum |
| Blue-eyed Grass | Sisyrinchium bellum |
| Blue-eyed Grass, Mountain | Sisyrinchium montanum |
| Blue-eyed Grass, Narrow-leaved | Sisyrinchium angustifolium |
| Blue-eyed Grass, Strict | Sisyrinchium montanum |
| Blue-eyed Mary, Spring | Collinsia verna |
| Blue-eyed Mary, Violet | Collinsia violacea |
| Bluestar, Fringed | Amsonia ciliata |
| Bluestar, Palmer's | Amsonia palmeri |
| Bluestem, Big | Andropogon gerardii |
| Bluestem, Little | Schizachyrium scoparium |
| Bluets | Houstonia caerulea |
| Bluets, Long-leaved | Houstonia longifolia |
| Bluets, Thyme-leaved | Houstonia serpyllifolia |
| Bluff Lettuce | Dudleya farinosa |
| Bog Arrow Grass, Common | Triglochin maritima |
| Bog Arrow Grass, Slender | Triglochin palustris |
| Bog Orchid, Round-leaved | Galearis rotundifolia |
| Bog Orchid, Slender | Platanthera stricta |
| Bog Orchid, White | Platanthera dilatata |
| Bog Orchid. Northern | Platanthera aquilonis |
| Bog Rosemary | Andromeda polifolia |
| Bog Violet | Pinguicula villosa |
| Bolete, Apple | Exsudoporus frostii |
| Boneset | Eupatorium perfoliatum |
| Boneset, Tall | Eupatorium altissimum |
| Bouncing Bet | Saponaria officinalis |
| Bower Plant | Pandorea jasminoides |
| Brackenfern | Pteridium aquilinum |
| Bride's Bonnet | Clintonia uniflora |
| Bristlehead, Bigelow's | Carphochaete bigelovii |
| British Soldiers | Cladonia cristatella |
| Brittlebush | Encelia farinosa |
| Brittlestem | Mabrya acerifolia |
| Brodiaea, Crown | Brodiaea coronaria ssp. coronaria |
| Brodiaea, Dwarf | Brodiaea terrestris ssp. terrestris |
| Brodiaea, Thread-leaved | Brodiaea filifolia |
| Brodiaea, White | Triteleia hyacinthina |
| Brome, Prairie | Bromus ciliatus |
| Bromeliad | Aechmia dichlamydea |
| Brook Lettuce | Micranthes micranthidifolia |
| Brookfoam, Coastal | Boykinia occidentalis |
| Brookfoam, Richardson's | Boykinia richardsonii |
| Broom, Spanish | Spartium junceum |
| Broomrape, Clustered | Aphyllon fasciculata |
| Broomrape, Desert | Aphyllon cooperi |
| Broomrape, One-flowered | Aphyllon purpureum |
| Broomrape, One-flowered | Aphyllon uniflora |
| Brown-Eyed Susan | Rudbeckia triloba |
| Buckbean | Menyanthes trifoliata |
| Buck-brush, Blue | Ceanothus cuneatus var. cuneatus |
| Buckeye, Mexican | Ungnadia speciosa |
| Buckeye, Ohio | Aesculus glabra |
| Buckeye, Pale | Aesculus pavia var. flavescens |
| Buckeye, Red | Aesculus pavia var. pavia |
| Buckeye, Red | Aesculus pavia var. flavescens |
| Buckwheat | Eriogonum sp. |
| Buckwheat, Alpine Golden | Eriogonum flavum |
| Buckwheat, Arrowleaf | Eriogonum compositum |
| Buckwheat, California | Eriogonum fasciculatum |
| Buckwheat, Cushion | Eriogonum ovalifolium |
| Buckwheat, Dune | Eriogonum parvifolium |
| Buckwheat, Fraziers Well | Eriogonum wrightii |
| Buckwheat, Parsnipflower | Eriogonum heracleoides |
| Buckwheat, Wright's | Eriogonum wrightii |
| Buffaloberry, Russet | Shepherdia canadensis |
| Bugleweed, Blue | Ajuga reptans |
| Bugleweed, Northern | Lycopus uniflorus |
| Bugleweed, Riverbank | Lycopus virginicus |
| Bulrush, Hard-stemmed | Schoenoplectus acutus |
| Bulrush, Red | Scirpus pendulus |
| Bunchberry | Cornus canadensis |
| Bunchberry, Western | Cornus unalaschkensis |
| Bur Reed, American | Sparganium americanum |
| Bur Reed, Common | Sparganium eurycarpum |
| Bur Reed, Narrow-leaved Floating | Sparganium angustifolium |
| Bur-Marigold, Nodding | Bidens cernua |
| Bur-Marigold, Tall | Bidens trichosperma |
| Burnet, Canadian | Sanguisorba canadensis |
| Burning Bush | Euonymus atropurpureus |
| Bush Clover, Prairie | Lespedeza leptostachya |
| Bush Clover, Round-headed | Lespedeza capitata |
| Bush Pea | Lathyrus brachycalyx var. zionis |
| Bush Sunflower, California | Encelia californica |
| Bushbean, Purple | Macroptilium atropurpureum |
| Bushmallow, Chaparral | Malacothamnus densiflorus |
| Butter-and-Eggs | Triphysaria eriantha ssp. eriantha |
| Butter-and-Eggs | Linaria vulgaris |
| Buttercup, Anderson's | Ranunculus andersonii |
| Buttercup, Bristly | Ranunculus hispidus |
| Buttercup, California | Ranunculus californicus |
| Buttercup, Early | Ranunculus fascicularis |
| Buttercup, Large | Ranunculus macranthus |
| Buttercup, Prairie | Ranunculus rhomboideus |
| Buttercup, Sagebrush | Ranunculus glaberrimus |
| Buttercup, Sand | Ranunculus andersonii |
| Buttercup, Swamp | Ranunculus hispidus var. nitidus |
| Buttercup, Western | Ranunculus occidentalis |
| Butterfly Weed | Asclepias tuberosa |
| Butterweed | Packera glabella |
| Butterweed, California | Senecio californicus |
| Butterweed, Shrubby | Senecio flaccidus |
| Butterwort, Common | Pinguicula vulgaris |
| Butterwort, Hairy | Pinguicula villosa |
| Buttonbush | Cephalanthus occidentalis |
| Buttter and Eggs, Pink | Triphysaria eriantha ssp. rosea |
| Cactus, Arizona Fishhook | Mammillaria grahamii |
| Cactus, Barrel | Ferocactus cylindraceus ssp. cylindraceus |
| Cactus, Beavertail | Opuntia basilaris |
| Cactus, Boyce Thompson Hedgehog | Echinocereus fasciculatus |
| Cactus, Claret-cup Hedgehog | Echinocereus triglochidiatus |
| Cactus, Desert Christmas | Cylindropuntia leptocaulis |
| Cactus, Engelmann's Hedgehog | Echinocereus engelmannii |
| Cactus, Fendler Hedgehog | Echinocereus fendleri |
| Cactus, Little Fishhook | Mammillaria tetrancistra |
| Cactus, Mojave Mound | Echinocereus triglochidiatus |
| Cactus, Nipple | Mammillaria dioica |
| Cactus, Nipple Beehive | Coryphantha macromeris |
| Cactus, Organ Pipe | Stenocereus thurberi |
| Cactus, Rusty Hedgehog | Echinocereus russanthus |
| Cactus, San Pedro | Trichocereus sp. |
| Cactus, Scarlet Hedgehog | Echinocereus coccineus |
| Cactus, Walkingstick | Cylindropuntia spinosior |
| Calamint, Limestone | Clinopodium glabrum |
| Calamint, Low | Clinopodium glabrum |
| Calicoflower, Maroonspot | Downingia concolor var. concolor |
| California Peony | Paeonia californica |
| Camas, Common | Camassia quamash |
| Camas, White | Anticlea elegans ssp. glauca |
| Campion, Bladder | Silene vulgaris |
| Campion, Moss | Silene acaulis |
| Campion, Starry | Silene stellata |
| Campion, White | Silene latifolia ssp. alba |
| Cancer Root, American | Conopholis americana |
| Candelilla | Euphorbia antisyphilitica |
| Candlenut | Aleurites moluccanus |
| Candy Flower | Claytonia sibirica |
| Canterbury Bells, Wild | Phacelia minor |
| Cardinal Flower | Lobelia cardinalis |
| Carolina Allspice | Calycanthus floridus |
| Carpet-weed, Green | Mollugo verticillata |
| Carrion Flower | Smilax lasioneura |
| Carrionflower, Upright | Smilax ecirrhata |
| Castor Bean | Ricinus communis |
| Catchfly, Royal | Silene regia |
| Catnip | Nepeta cataria |
| Cat's Whiskers | Orthosiphon aristatus |
| Cattail, Common | Typha latifolia |
| Cattail, Narrow-leaved | Typha angustifolia |
| Ceanothus, Desert | Ceanothus greggii |
| Ceanothus, Greenbark | Ceanothus spinosus |
| Ceanothus, Hoary-leaved | Ceanothus crassifolius |
| Celandine | Chelidonium majus |
| Cenizo | Leucophyllum frutescens |
| Century Plant, Chisos Mountain | Agave x glomeruliflora |
| Cereus, Night-Blooming | Hylocereus undatus |
| Chaffhead, Hairy | Carphephorus paniculatus |
| Chandelier Plant | Kalanchoe delagoensis |
| Chciweed, Water | Stellaria aquatica |
| Checkerberry | Gaultheria procumbens |
| Checkerbloom | Sidalcea malviflora |
| Checkerbloom, Oregon | Sidalcea oregana |
| Cheese Bush | Hymenoclea salsola |
| Cheesewood, Kona | Pittosporum hosmeri |
| Cherry, Choke | Prunus virginiana |
| Cherry, Great Lakes Sand | Prunus pumila var. pumila |
| Cherry, Sour | Prunus cerasus |
| Cherry, Taiwan | Prunus campanulata |
| Cherry, Wild Black | Prunus serotina |
| Chia | Salvia columbariae |
| Chicken of the Woods | Laetiporus sulphureus |
| Chickweed, Common | Stellaria meadia |
| Chickweed, Field | Cerastium arvense |
| Chickweed, Giant | Stellaria aquatica |
| Chickweed, Giant | Stellaria pubera |
| Chickweed, Mouse-ear | Cerastium fontanum |
| Chicory | Cichorium intybus |
| Chicory, Desert | Rafinesquia neomexicana |
| Chinese Houses, Purple | Collinsia heterophylla |
| Chinese Houses, Southern | Collinsia concolor |
| Chinese violet | Asystasia gangetica |
| Chokeberry | Aronia x prunifolia |
| Chokeberry, Black | Aronia melanocarpa |
| Cholla, Buckhorn | Cylindropuntia acanthocarpa |
| Cholla, Chainfruit | Cylindropuntia fulgida var. fulgida |
| Cholla, Hanging Chain | Cylindropuntia fulgida var. fulgida |
| Cholla, Jumping | Cylindropuntia bigelovii |
| Cholla, Wolf's | Cylindropuntia wolfii |
| Christmas Berry | Schinus terebinthifolius |
| Christmas Berry | Heteromeles arbutifolia |
| Christmasberry | Lycium carolinianum |
| Chuparosa | Justicia californica |
| Cinquefoil, Alpine | Potentilla villosa |
| Cinquefoil, Common | Potentilla simplex |
| Cinquefoil, High Mountain | Potentilla flabellifolia |
| Cinquefoil, Marsh | Comarum palustre |
| Cinquefoil, Prairie | Drymocallis arguta |
| Cinquefoil, Rough | Potentilla norvegica |
| Cinquefoil, Shrubby | Dasiphora fruticosa |
| Cinquefoil, Sulfur | Potentilla recta |
| Cinquefoil, Villous | Potentilla villosa |
| Clammy Weed | Polanisia dodecandra |
| Clearweed | Pilea pumila |
| Cleavers | Galium aparine |
| Clematis, Hairy | Clematis hirsutissima |
| Clematis, Pipestem | Clematis lasiantha |
| Clematis, Western White | Clematis ligusticifolia |
| Cliffrose, Arizona | Purshia x subintegra |
| Cliffrose, Mexican | Purshia mexicana |
| Cliffrose, Stansbury | Purshia stansburiana |
| Clintonia | Clintonia borealis |
| Clintonia, Andrew's | Clintonia andrewsiana |
| Clintonia, Red | Clintonia andrewsiana |
| Clintonia, White | Clintonia umbellatum |
| Clover, Cowbag | Trifolium depauperatum |
| Clover, King's | Trifolium kingii ssp. macilentum |
| Clover, Large-headed | Trifolium macrocephalum |
| Clover, Lean | Trifolium kingii ssp. macilentum |
| Clover, Tomcat | Trifolium willdenovii |
| Clover, Variegated | Trifolium variegatum |
| Clubmoss, Fan | Diphasiastrum digitatum |
| Clubmoss, Running | Lycopodium clavatum |
| Clubmoss, Sand | Selaginella rupestris |
| Clubmoss, Staghorn | Lycopodiella cernua |
| Clustervine, Skyblue | Jacquemontia pentanthos |
| Coastal Tidytips | Layia platyglossa |
| Coffee | Coffea arabica |
| Cohosh, Blue | Caulophyllum thalictroides |
| Colicwood | Myrsine lessertiana |
| Collared Annual Lupine | Lupinus truncatus |
| Collinsia, Few-flowered | Collinsia sparsiflora |
| Coltsfoot | Tussilago farfara |
| Columbine | Aquilegia canadensis |
| Columbine, Colorado Blue | Aquilegia coerulea |
| Columbine, Common | Aquilegia vulgaris |
| Columbine, European | Aquilegia vulgaris |
| Columbine, Western | Aquilegia formosa |
| Columbine, Yellow | Aquilegia flavescens |
| Comfrey, Wild | Cynoglossum virginianum |
| Common Fiddleneck | Amsinckia menziesii |
| Common Linanthus | Leptosiphon parviflorus |
| Common Muilla | Muilla maritima |
| Common Reed | Phragmites australis |
| Compass Plant | Silphium laciniatum |
| Compassplant, California | Wyethia angustifolia |
| Coneflower, Cutleaf | Rudbeckia laciniata var. laciniata |
| Coneflower, Green-headed | Rudbeckia laciniata var. laciniata |
| Coneflower, Pale Purple | Echinacea pallida |
| Coneflower, Purple | Echinacea purpurea |
| Coneflower, Sweet | Rudbeckia subtomentosa |
| Coneflower, Yellow | Ratibida pinnata |
| Coral Creeper | Barleria repens |
| Coralroot, Early | Corallorhiza trifida |
| Coralroot, Pacific | Corallorhiza mertensiana |
| Coralroot, Spotted | Corallorhiza maculata |
| Coralroot, Striped | Corallorhiza striata |
| Coralroot, Western | Corallorhiza mertensiana |
| Cordgrass, Sand | Sporobolus bakeri |
| Coreopsis, Giant | Leptosyne gigantea |
| Coreopsis, Sand | Coreopsis lanceolata |
| Coreopsis, Stiff | Coreopsis palmata |
| Coreopsis, Stillman's | Coreopsis stillmanii |
| Coreopsis, Tall | Coreopsis tripteris |
| Cornel, Lapland | Cornus suecica |
| Corydalis, Golden | Corydalis aurea |
| Corydalis, Pale | Corydalis flavula |
| Corydalis, Pink | Corydalis sempervirens |
| Corydalis, Scouler's | Corydalis scouleri |
| Cotton Grass, Dense | Eriophorum vaginatum |
| Cotton Grass, Hare's-tail | Eriophorum vaginatum |
| Cotton Grass, Narrow-Leaved | Eriophorum angustifolium |
| Cotton Grass, Rusty | Eriophorum virginicum |
| Cotton Grass, White | Eriophorum scheuchzeri |
| Cottongrass, Few-nerved | Eriophorum tenellum |
| Cottonweed, Large | Froelichia floridana |
| Cottonwood, Fremont | Populus fremontii |
| Cow Parsnip | Heracleum sphondylium ssp. montanum |
| Cow Wheat, Narrowleaf | Melampyrum lineare |
| Cowbane | Oxypolis rigidior |
| Cowslip, European | Primula veris |
| Crab Apple, Iowa | Malus ioensis |
| Cracked Lichen, Schleicher's | Acarospora schleicheri |
| Cranberry, Large | Vaccinium macrocarpon |
| Cranberry, Small-fruited | Vaccinium oxycoccos |
| Cream Cups | Platystemon californicus |
| Cream Sacs | Castilleja rubicundula ssp. lithospermoides |
| Creeper, Japanese | Parthenocissus tricuspidata |
| Creeper, Virginia | Parthenocissus quinquefolia |
| Creeping Jenny | Lysimachia nummularia |
| Creeping Mahonia | Berberis repens |
| Creeping-oxeye | Sphagneticola trilobata |
| Creosote Bush | Larrea tridentata |
| Cress, Bulbous | Cardamine bulbosa |
| Cress, Rock | Arabis sp. |
| Cress, Sand | Arabidopsis lyrata |
| Cress, Spring | Cardamine douglassii |
| Cress, Whitlow | Tomostima reptans |
| Cress, Winter | Barbarea vulgaris |
| Crocus, Dutch | Crocus vernus |
| Croton, Cortez's | Croton cortesianus |
| Croton, Sand | Croton glandulosus var. septentrionalis |
| Crow Poison | Nothoscordum bivalve |
| Crowberry, Black | Empetrum nigrum |
| Crown Vetch | Securigera varia |
| Cryptantha, Common | Cryptantha intermedia |
| Cryptantha, Cushion | Cryptantha circumscissa |
| Cuckoo-Flower | Cardamine pratensis |
| Cucumber Root, Indian | Medeola virginiana |
| Cucumber, Wild | Echinocystis lobata |
| Cucumber, Wild | Marah macrocarpus |
| Culver's Root | Veronicastrum virginicum |
| Cup Plant | Silphium perfoliatum |
| Currant, American Black | Ribes americanum |
| Currant, White-flowering | Ribes indecorum |
| Currants, Wax | Ribes cereum |
| Cypress, Pond | Taxodium ascendens |
| Daffodil | Narcissus pseudonarcissus |
| Daisy Fleabane | Erigeron strigosus |
| Daisy Fleabane, Marsh | Erigeron philadelphicus |
| Daisy, Blackfoot | Melampodium leucanthum |
| Daisy, Camphor | Rayjacksonia phyllocephala |
| Daisy, Cutleaf | Erigeron compositus |
| Daisy, Lakeside | Tetraneuris herbacea |
| Daisy, Ox-Eye | Leucanthemum vulgare |
| Daisy, Seaside | Erigeron glaucus |
| Daisy, Stemmy Four-nerve | Tetraneuris scaposa var. scaposa |
| Daisy, Wallace's Woolly | Eriophyllum wallacei |
| Dalea | Dalea pulchra |
| Dalea, Bearded | Dalea pogonathera var. pogonathera |
| Dalea, Feather | Dalea pogonathera var. pogonathera |
| Dame's Rocket | Hesperis matronalis |
| Dandelion, Desert | Malacothrix glabrata |
| Dandelion, Dwarf | Krigia virginica |
| Dayflower, Climbing | Commelina diffusa |
| Dayflower, Narrow-Leaved | Commelina erecta |
| Daylily, Orange | Hemerocallis fulva |
| Dead Nettle, Purple | Lamium purpureum |
| Deadnettle, Henbit | Lamium amplexicaule |
| Death Camas, Fremont's | Toxicoscordion fremontii |
| Death Camas, Meadow | Toxicoscordion venenosum |
| Death Camas, Mountain | Anticlea elegans ssp. elegans |
| Deer Cabbage | Nephrophyllidium crista-galli |
| Deerweed, Common | Acmispon glaber |
| Delphinium, Bilobed | Delphinium nuttallianum |
| Dendrobium Orchid | Dendrobium sp. |
| Deptford Pinks | Dianthus armeria |
| Desert Apricot | Prunus fremontii |
| Desert Fivespot | Eremalche rotundifolia |
| Desert Hollyhock | Sphaeralcea ambigua |
| Desert Marigold | Baileya multiradiata |
| Desert Prince's Plume | Stanleya pinnata |
| Desert Senna | Senna covesii |
| Desert Snapdragon, Golden | Mohavea breviflora |
| Desert Star | Monoptilon bellioides |
| Desert Sunflower, Hairy | Geraea canescens |
| Desert Thornapple | Datura discolor |
| Desert Trumpets | Eriogonum inflatum |
| Desertbells | Phacelia campanularia |
| Desert-Rue, Mojave | Thamnosma montana |
| Devil's Club | Oplopanax horridus |
| Devil's-tongue | Opuntia humifusa |
| Dewberry, Northern | Rubus flagellaris |
| Dock, Curled | Rumex crispus |
| Dock, Great Water | Rumex britannica |
| Dock, Pale | Rumex altissimus |
| Dodder, Common | Cuscuta gronovii |
| Dodder, Rope | Cuscuta glomerata |
| Dog Hobble | Leucothoe fontanesiana |
| Dogbane, Spreading | Apocynum androsaemifolium |
| Dogfennel | Eupatorium capillifolium |
| Dogweed | Thymophylla pentachaeta |
| Dogwood, Alternate-leaved | Cornus alternifolia |
| Dogwood, Flowering | Cornus florida |
| Dogwood, Gray | Cornus racemosa |
| Dogwood, Pacific | Cornus nuttallii |
| Dogwood, Redosier | Cornus sericea |
| Dogwood, Round Leaved | Cornus rugosa |
| Dogwood, Silky | Cornus obliqua |
| Douglasia, Smooth | Androsace laevigata |
| Downingia, Spotted-throat | Downingia concolor var. concolor |
| Draba, Wedgeleaf | Tomostima cuneifolia |
| Dragonfruit | Hylocereus undatus |
| Dropseed, Prairie | Sporobolus heterolepis |
| Dropseed, Rough | Sporobolus compositus var.compositus |
| Drops-of-gold | Prosartes hookeri |
| Drumheads | Polygala cruciata |
| Dubautia, Rough | Dubautia scabra |
| Duck Potato | Sagittaria lancifolia |
| Duckweed | Lemna sp. |
| Dudleya, Chalk | Dudleya pulverulenta |
| Dudleya, Lance-leaved | Dudleya lanceolata |
| Dudleya, Rock | Dudleya saxosa ssp. collomiae |
| Dusty Maiden | Chaenactis douglasii |
| Dutchman's Breeches | Dicentra cucullaria |
| Dwarf Bramble | Rubus pedatus |
| Dwarf Cornel, Swedish | Cornus suecica |
| Dwarf Palmetto | Sabal minor |
| Dwarf-Primrose, Cliff | Androsace laevigata |
| Echeveria, Rock | Dudleya saxosa ssp. collomiae |
| Elder, Red-berried | Sambucus racemosa var. racemosa |
| Elderberry | Sambucus canadensis |
| Elm, Winged | Ulmus alata |
| Enchanter's Nightshade | Circaea canadensis |
| Eskimo Potato | Hedysarum alpinum |
| Eucalyptus, Rainbow | Eucalyptus deglupta |
| Evening Primrose, Beach | Camissoniopsis cheiranthifolia |
| Evening Primrose, Booth | Eremothera boothii |
| Evening Primrose, Brown-eyed | Chylismia claviformis |
| Evening Primrose, Common | Oenothera biennis |
| Evening Primrose, Dandelion | Oenothera flava ssp. taraxacoides |
| Evening Primrose, Desert | Oenothera primiveris |
| Evening Primrose, Dune | Oenothera deltoides |
| Evening Primrose, Hairy | Oenothera villosa |
| Evening Primrose, Mustard | Eulobus californica |
| Evening Primrose, Narrow-leaved | Eremothera refracta |
| Evening Primrose, Sand | Oenothera clelandii |
| Evening Primrose, Showy | Oenothera grandis |
| Evening Primrose, Toothed | Oenothera serrulata |
| Evening Primrose, Tufted | Oenothera caespitosa |
| Evening Primrose, Yellow | Oenothera flava ssp. taraxacoides |
| Everlasting, Pearly | Anaphalis margaritacea |
| Fagonbush, California | Fagonia laevis |
| Fairy Pins | Phaeocalicium polyporaeum |
| Fairybell, Smith's | Prosartes smithii |
| Fairy-bells | Prosartes hookeri |
| Fairybells, Largeflower | Prosartes smithii |
| Fairybells, Yellow | Prosartes lanuginosa |
| Fairyduster | Calliandra eriophylla |
| Fairy-lantern, Golden | Calochortus amabilis |
| Fairy-lantern, White | Calochortus albus |
| Fairy-Swords | Myriopteris lindheimeri |
| Fairywand | Chamaelirium luteum |
| False Asphodel | Triantha glutinosa |
| False Aster | Boltonia asteroides |
| False Azalea | Rhododendron menziesii |
| False Boneset | Brickellia eupatorioides var. corymbulosa |
| False Buckwheat, Climbing | Fallopia scandens |
| False Dandelion | Krigia biflora |
| False Foxglove | Agalinis sp. |
| False Foxglove, Clammy | Aureolaria pedicularia |
| False Foxglove, Purple | Agalinis purpurea |
| False Foxglove, Rough | Agalinis aspera |
| False Foxglove, Slender | Agalinis tenuifolia |
| False Foxglove, Yellow | Aureolaria grandiflora |
| False Garlic | Nothoscordum bivalve |
| False Hellebore, California | Veratrum californicum |
| False Hellebore, Green | Veratrum viride |
| False Nightshade | Chamaesaracha sordida |
| False Nightshade, Woolly | Chamaesaracha villosa |
| False Pennyroyal | Trichostema brachiatum |
| False Rue Anemone | Enemion biternatum |
| False Solomon's Seal, Plumy | Maianthemum racemosum |
| False Solomon's Seal, Starry | Maianthemum stellatum |
| False Solomon's Seal, Three-leaf | Maianthemum trifolium |
| Fan Palm | Washingtonia filifera |
| Featherplume | Dalea formosa |
| Fern, Aleutian Maidenhair | Adiantum aleuticum |
| Fern, Ama'uma'u | Sadleria cyatheoides |
| Fern, Blunt-loped Cliff | Woodsia obtusa |
| Fern, Broad Beech | Phegopteris hexagonoptera |
| Fern, Bulblet | Cystopteris bulbifera |
| Fern, California Maidenhair | Adiantum jordanii |
| Fern, Christmas | Polystichum acrostichoides |
| Fern, Cinnamon | Osmundastrum cinnamomea |
| Fern, Common Lady | Athyrium filix-femina |
| Fern, Common Maidenhair | Adiantum capillus-veneris |
| Fern, Cut-leaved Grape | Sceptridium dissectum |
| Fern, Deer | Blechnum spicant |
| Fern, Five-fingered | Adiantum aleuticum |
| Fern, Fragile | Cystopteris fragilis |
| Fern, Hard | Blechnum spicant |
| Fern, Hay-scented | Dennstaedtia punctilobula |
| Fern, Interrupted | Osmunda claytoniana |
| Fern, Long Beech | Phegopteris connectilis |
| Fern, Maidenhair | Adiantum pedatum |
| Fern, Marsh Shield | Thelypteris palustris |
| Fern, New York | Amauropelta noveboracensis |
| Fern, Ostrich | Matteuccia struthiopteris |
| Fern, Rattlesnake | Botrypus virginianum |
| Fern, Resurrection | Pleopeltis michauxiana |
| Fern, Royal | Osmunda regalis |
| Fern, Sensitive | Onoclea sensibilis |
| Fern, Spinulose Wood | Dryopteris carthusiana |
| Fern, Walking | Asplenium rhizophyllum |
| Feverwort | Triosteum perfoliatum |
| Field Sorrel | Rumex acetosella |
| Fieldcap, Spring | Agrocybe praecox |
| Fiesta Flower, Arizona | Pholistoma auritum var. arizonicum |
| Fiesta Flower, White | Pholistoma membranaceum |
| Fiesta-flower, Blue | Pholistoma auritum var. auritum |
| Fig, Hottentot | Carpobrotus edulis |
| Fig, Sea | Carpobrotus chilensis |
| Figwort, California | Scrophularia californica |
| Fir, Balsam | Abies balsamea |
| Fir, Subalpine | Abies lasiocarpa |
| Fireweed | Senecio madagascariensis |
| Fireweed | Chamerion angustifolium ssp. angustifolium |
| Fireweed | Chamerion angustifolium ssp. circumvagum |
| Fireweed, Dwarf | Chamerion latifolium |
| Fishers Orchid | Dactylorhiza aristata |
| Five Eyes, TransPecos | Chamaesaracha villosa |
| Fivespot | Nemophila maculata |
| Flag, Larger Blue | Iris versicolor |
| Flannelbush | Fremontodendron californicum |
| Flax, Common | Linum usitatissimum |
| Flax, Grooved Yellow | Linum sulcatum |
| Fleabane, Annual | Erigeron annuus |
| Fleabane, Aspen | Erigeron speciosus |
| Fleabane, Coastal | Erigeron peregrinus |
| Fleabane, Navajo | Erigeron concinnus |
| Fleabane, Subalpine | Erigeron peregrinus |
| Floating Heart | Nymphoides cordata |
| Floating Heart, Yellow | Nymphoides peltata |
| Flower-of-an-Hour | Hibiscus trionum |
| Foamflower | Tiarella cordifolia |
| Foamflower, Threeleaf | Tiarella trifoliata |
| Fog Fruit | Phyla lanceolata |
| Forget-Me-Not | Myosotis scorpioides |
| Forget-me-not, Alpine | Myosotis asiatica |
| Forget-Me-Not, Large-Seeded | Myosotis macrosperma |
| Forked Fern | Dicranopteris linearis |
| Four O'Clock, California | Mirabilis laevis var. laevis |
| Four O'clock, Desert White | Mirabilis laevis var. villosa |
| Four O'Clock, Heartleaf | Mirabilis nyctaginea |
| Four O'clock, Trailing | Allionia incarnata |
| Four O'Clock, Wild | Mirabilis laevis var. laevis |
| Foxglove, Mullein | Dasistoma macrophylla |
| Foxglove, Purple | Digitalis purpurea |
| Foxglove, Yellow | Digitalis grandiflora |
| Frangipani | Plumeria sp. |
| Fringetree, White | Chionanthus virginicus |
| Fritillary, Fragrant | Fritillaria liliacea |
| Fritillary, Yellow | Fritillaria pudica |
| Frog Orchid, Long-Bract | Dactylorhiza viridis |
| Frost Mat | Achyronychia cooperi |
| Frying Pans | Eschscholzia lobbii |
| Fumewort, Curvepod | Corydalis curvisiliqua |
| Fumewort, Scouler's | Corydalis scouleri |
| Fumewort, Yellow | Corydalis flavula |
| Garland-lily, Cream | Hedychium flavescens |
| Garland-lily, Kahila | Hedychium gardnerianum |
| Garlic, Wild | Allium canadense |
| Gaywings | Polygala paucifolia |
| Gentian, Billington's | Gentiana x billingtonii |
| Gentian, Bottle | Gentiana andrewsii |
| Gentian, Closed | Gentiana clausa |
| Gentian, Fringed | Gentianopsis crinita |
| Gentian, Glaucous | Gentiana glauca |
| Gentian, plain | Gentiana alba |
| Gentian, Prairie | Gentiana puberulenta |
| Gentian, Rainier Pleated | Gentiana calycosa |
| Gentian, Small Fringed | Gentianopsis virgata |
| Gentian, Soapwort | Gentiana saponaria |
| Gentian, Stiff | Gentianella quinquefolia ssp. quinquefolia |
| Geranium, Richardson's | Geranium richardsonii |
| Geranium, Sticky Purple | Geranium viscosissimum |
| Geranium, Wild | Geranium maculatum |
| Geranium, Wild | Geranium erianthum |
| Geranium, Woolly | Geranium erianthum |
| Germander | Teucrium canadense var. occidentale |
| Ghostflower | Mohavea confertiflora |
| Giant Hyssop, Nettleleaf | Agastache urticifolia |
| Giant Hyssop, Purple | Agastache scrophulariaefolia |
| Gila, Showy | Gilia cana |
| Gilia | Gilia sp. |
| Gilia, Blue-headed | Gilia capitata |
| Gilia, Golden | Leptosiphon chrysanthus |
| Gilia, Lesser Yellowthroat | Gilia flavocincta |
| Gilia, Scarlet | Ipomopsis aggregata |
| Gilia, Star | Gilia stellata |
| Ginger, Kahila | Hedychium gardnerianum |
| Ginger, Wild | Asarum canadense |
| Ginger, Yellow | Hedychium flavescens |
| Ginseng, Dwarf | Panax trifolius |
| Glacier-lily, Yellow | Erythronium grandiflorum |
| Glademallow | Napaea dioica |
| Globeflower, American | Trollius laxus |
| Globelily, Golden | Calochortus amabilis |
| Globemallow, Caliche | Sphaeralcea laxa |
| Globemallow, Scarlet | Sphaeralcea coccinea |
| Glorybush | Tibouchina urvilleana |
| Goat's Beard | Tragopogon pratensis |
| Goat's Beard, Sand | Tragopogon dubius |
| Goat's Rue | Tephrosia virginiana |
| Golden Alexander | Zizia aurea |
| Golden Alexander, Heart-leaved | Zizia aptera |
| Golden Banner | Thermopsis californica |
| Golden Carpet | Gilmania luteola |
| Golden Cryptanth | Cryptantha confertiflora |
| Golden Dewdrops | Duranta erecta |
| Golden Eardrops | Dicentra chrysantha |
| Goldenaster, Lemonyellow False | Heterotheca camporum |
| Goldenbush, Narrowleaf | Ericameria linearifolia |
| Goldeneye, Death Valley | Bahiopsis reticulata |
| Goldeneye, Netvein | Bahiopsis reticulata |
| Goldeneye, Parish's | Bahiopsis parishii |
| Goldenrod, Bog | Solidago uliginosa |
| Goldenrod, Canada | Solidago canadensis |
| Goldenrod, Early | Solidago juncea |
| Goldenrod, Elm-leaved | Solidago ulmifolia |
| Goldenrod, Grass-leaved | Euthamia graminifolia |
| Goldenrod, Late | Solidago gigantea |
| Goldenrod, Missouri | Solidago missouriensis var fasciculata |
| Goldenrod, Northern | Solidago multiradiata |
| Goldenrod, Ohio | Solidago ohioensis |
| Goldenrod, Oldfield | Solidago nemoralis |
| Goldenrod, Prairie | Solidago x lutescens |
| Goldenrod, Riddell's | Solidago riddellii |
| Goldenrod, Rocky Mountain | Solidago multiradiata |
| Goldenrod, Seaside | Solidago sempervirens |
| Goldenrod, Showy | Solidago speciosa |
| Goldenrod, Stiff | Solidago rigidum var. rigidum |
| Goldenrod, Swamp | Solidago patula |
| Goldenrod, Tall | Solidago altissima |
| Goldenrod, White Prairie | Solidago ptarmicoides |
| Goldenrod, Wreath | Solidago caesia |
| Goldenrod, Zigzag | Solidago flexicaulis |
| Goldenseal | Hydrastis canadensis |
| Goldenstar | Erythronium rostratum |
| Goldenstar, Common | Bloomeria crocea |
| Goldfields, California | Lasthenia californica |
| Gooseberry, California | Ribes californicum |
| Gooseberry, Fuchsia-flowered | Ribes speciosum |
| Grape, Riverbank | Vitis riparia |
| Grass of Parnassus | Parnassia glauca |
| Grass of Parnassus, Alaska | Parnassia palustris |
| Grass Widows | Olsynium douglasii |
| Grass, Bottlebrush | Elymus hystrix var. hystrix |
| Grass, Cord | Sporobolus michauxianus |
| Grass, Fowl Mana | Glyceria striata |
| Grass, Indian | Sorghastrum nutans |
| Grass, June | Koeleria macrantha |
| Grass, Porcupine | Hesperostipa spartea |
| Grass, Prairie Panic | Dichanthelium leibergii |
| Grass, Scribner's Panic | Dichanthelium oligosanthes var scribnerianum |
| Grass, Tufted Hair | Deschampsia cespitosa |
| Grass, Vanilla | Anthoxanthum hirtum |
| Gravel Ghost | Atrichoseris platyphylla |
| Greek Valerian | Polemonium reptans |
| Green Dragon | Arisaema dracontium |
| Greenbrier, Cat | Smilax glauca |
| Greenviolet, Eastern | Hybanthus concolor |
| Gromwell, American | Lithospermum latifolium |
| Ground Cedar | Lycopodium complanatum |
| Ground Cherry, Clammy | Physalis heterophylla |
| Ground Cherry, Lance-leaved | Physalis virginiana |
| Ground Cherry, Tall | Physalis longifolia |
| Ground Cherry, Thick-leaved | Physalis crassifolia |
| Ground Ivy | Glechoma hederacea |
| Ground Pine, Running | Lycopodium clavatum |
| Ground Pink | Linanthus dianthiflorus |
| Ground Plum | Astragalus crassicarpus |
| Groundcherry, Purple | Quincula lobata |
| Groundsel, Black-tipped | Senecio lugens |
| Groundsel, Golden | Packera obovata |
| Groundsel, Prairie | Packera plattensis |
| Guava, Strawberry | Psidium cattleyanum |
| Gum Plant | Grindelia squarrosa |
| Gum, Mindanao | Eucalyptus deglupta |
| Hala | Pandanus tectorius |
| Hanging Lobster Claw | Heliconia sp. |
| Harebell | Campanula rotundifolia |
| Harebell, Mountain | Campanula lasiocarpa |
| Harvestbells | Gentiana saponaria |
| Hau | Hibiscus tiliaceus |
| Hawkweed, Field | Hieracium caespitosum |
| Hawkweed, Hairy | Hieracium gronovii |
| Hawkweed, Orange | Hieracium aurantiacum |
| Hawthorn, Hawaii | Osteomeles anthyllidifolia |
| Hazelnut, American | Corylus americana |
| Heather, Western Moss | Cassiope mertensiana |
| Heather, White | Cassiope mertensiana |
| Hedgenettle, Coastal | Stachys chamissonis |
| Hedgenettle, Marsh | Stachys hispida |
| Hedgenettle, Rigid | Stachys rigida var. rigida |
| Hedgenettle, Scarlet | Stachys coccinea |
| Heliconia, Sexy Pink | Heliconia chartacea |
| Heliconia, Striped | Heliconia indica |
| Heliotrope, Wild | Heliotropium curassavicum |
| Helleborine | Epipactis helleborine |
| Hemlock, Eastern | Tsuga canadensis |
| Hempnettle, brittlestem | Galeopsis tetrahit |
| Hempvine, Climbing | Mikania scandens |
| Hepatica, Round-lobed | Anemone americana |
| Hepatica, Sharp-lobed | Anemone acutiloba |
| Herb-Robert | Geranium robertianum |
| Hibiscus | Hibiscus sp. |
| Hibiscus, Heartleaf | Hibiscus martianus |
| Hibiscus, Sea | Hibiscus tiliaceus |
| Hibiscus, Turks Cap | Malvaviscus penduliflorus |
| Hideseed, Spotted | Eucrypta chrysanthemifolia |
| Highbush Cranberry, American | Viburnum opulus var. americanum |
| Ho'awa | Pittosporum hosmeri |
| Hobblebush | Viburnum lantanoides |
| Hog Peanut | Amphicarpaea bracteata |
| Holly, Mountain | Ilex mucronata |
| Holly, Swamp | Ilex mucronata |
| Hollyhock, Mountain | Iliamna rivularis |
| Honeysuckle, American Fly | Lonicera canadensis |
| Honeysuckle, Amur | Lonicera maackii |
| Honeysuckle, Desert | Anisacanthus thurberi |
| Honeysuckle, Limber | Lonicera dioica |
| Honeysuckle, Northern Bush | Diervilla lonicera |
| Honeysuckle, Pink | Lonicera hispidula var. vacillans |
| Honeysuckle, Red | Lonicera dioica |
| Honeysuckle, Swamp Fly | Lonicera oblongifolia |
| Honeysuckle, Twinberry | Lonicera involucrata var. ledebourii |
| Honeysuckle, Twinberry | Lonicera involucrata |
| Honeysuckle, Yellow | Lonicera reticulata |
| Honohono | Commelina diffusa |
| Hopbush | Dodonaea viscosa |
| Hoptree, Common | Ptelea trifoliata |
| Hornbeam, American | Carpinus caroliniana |
| Hornbeam, Hop | Ostrya virginiana |
| Horse Nettle | Solanum carolinense |
| Horse-Gentian | Triosteum perfoliatum |
| Horsemint, Ohio | Blephilia ciliata |
| Horsetail, Common | Equisetum arvense |
| Horsetail, Small | Equisetum scirpoides |
| Horsetail, Smooth | Equisetum laevigatum |
| Horsetail, Woodland | Equisetum sylvaticum |
| Houndstongue | Cynoglossum officinale |
| Huckleberry, Black | Gaylussacia baccata |
| Huckleberry, Box | Gaylussacia baccata |
| Huckleberry, Mountain | Vaccinium membranaceum |
| Huckleberry, Red | Vaccinium parvifolium |
| Huckleberry, Thinleaf | Vaccinium membranaceum |
| Hyacinth, Grape | Muscari botryoides |
| Hyacinth, Water | Eichhornia crassipes |
| Hyacinth, Wild | Dichelostemma capitatum |
| Hyacinth, Wild | Camassia scilloides |
| Hybrid Bottle Gentian | Gentiana x pallidocyanea |
| Iliau | Wilkesia gymnoxiphium |
| ilima, yellow | Sida fallax |
| Impatiens | Impatiens walleriana |
| Indian Hemp | Apocynum cannabinum |
| Indian Paintbrush, Christ's | Castilleja christii |
| Indian Paintbrush, Downy | Castilleja purpurea |
| Indian Paintbrush, Entireleaf | Castilleja indivisa |
| Indian Paintbrush, Giant Red | Castilleja miniata |
| Indian Paintbrush, Giant Red | Castilleja miniata |
| Indian Paintbrush, Harsh | Castilleja hispida |
| Indian Paintbrush, Mountain | Castilleja parviflora |
| Indian Paintbrush, Port Clarence | Castilleja caudata |
| Indian Paintbrush, Rough | Castilleja scabrida |
| Indian Paintbrush, Slickrock | Castilleja scabrida |
| Indian Pipe | Monotropa uniflora |
| Indian Plantain, Pale | Arnoglossum atriplicifolium |
| Indian Plantain, Prairie | Arnoglossum plantagineum |
| Indian Plantain, Sweet-scented | Senecio suaveolens |
| Indian Warrior | Pedicularis densiflora |
| Indianmallow, False | Allowissadula holosericea |
| Indian-tobacco | Lobelia inflata |
| Indigo Bush | Amorpha fruticosa |
| Indigo Bush, Shott's | Psorothamnus schottii |
| Insideout Flower, Redwood | Vancouveria planipetala |
| Ipecac, American | Gillenia stipulata |
| Iris, Beachhead | Iris setosa |
| Iris, Blue Flag | Iris virginica |
| Iris, Bowl-tube | Iris macrosiphon |
| Iris, Douglas | Iris douglasiana |
| Iris, Dwarf Crested | Iris cristata |
| Iris, Dwarf Lake | Iris lacustris |
| Iris, Dwarf Violet | Iris verna |
| Iris, Foothill | Iris hartwegii |
| Iris, German | Iris germanica |
| Iris, Ground | Iris macrosiphon |
| Iris, Hartweg's | Iris hartwegii |
| Iris, Siberian | Iris sibirica |
| Iris, Tall Yellow | Iris pseudacorus |
| Iris, Toughleaf | Iris tenax |
| Iris, Walking | Neomarica gracilis |
| Iris, Western Blue Flag | Iris missouriensis |
| Ironweed, Common | Vernonia fasciculata |
| Ironwood | Ostrya virginiana |
| Ithuriel's Spear | Triteleia laxa |
| Ivy, Boston | Parthenocissus tricuspidata |
| Ivy, Cape | Delairea odorata |
| Jacaranda | Jacaranda mimosifolia |
| Jack-in-the-Pulpit | Arisaema triphyllum |
| Jacob's Ladder | Polemonium reptans |
| Jacob's Ladder, California | Polemonium californicum |
| Jacob's Ladder, Leafy | Polemonium foliosissimum |
| Jacob's Ladder, Low | Polemonium californicum |
| Jacob's Ladder, Tall | Polemonium acutiflorum |
| Jacob's Ladder, Towering | Polemonium foliosissimum |
| Jacob's-ladder, Showy | Polemonium pulcherrimum |
| Jasmine, Pink | Jasminum polyanthum |
| Jelly Rot | Phlebia tremellosa |
| Jewelflower | Caulanthus heterophyllus |
| Jewelflower, Cooper' | Caulanthus cooperi |
| Jewelflower, Coulter's | Caulanthus coulteri |
| Jewelweed | Impatiens capensis |
| Jewelweed, Ornamental | Impatiens glandulifera |
| Jewelweed, Yellow | Impatiens pallida |
| Jimsonweed, Western | Datura wrightii |
| Joe Pye Weed, Purple | Eutrochium purpureum |
| Joe Pye Weed, Spotted | Eutrochium maculatus var. maculatus |
| Johnny Jumpup | Viola pedunculata |
| Johnny-Nip | Castilleja ambigua |
| Johnny-tuck | Triphysaria eriantha ssp. rosea |
| Jointfir | Ephedra sp. |
| Joshua Tree | Yucca brevifolia |
| Juneberry, Northern | Amelanchier interior |
| Juniper, Alligator | Juniperus deppeana |
| Juniper, Common | Juniperus communis |
| Juniper, Creeping | Juniperus horizontalis |
| Juniper, Ground | Juniperus communis |
| Juniper, Utah | Juniperus osteosperma |
| Keyflower | Dactylorhiza aristata |
| Kidneyvetch, Common | Anthyllis vulneraria |
| King of the Meadow | Thalictrum pubescens |
| King's Crown | Rhodiola integrifolia ssp. integrifolia |
| Kinnikinnick | Arctostaphylos uva-ursa |
| Kittentails | Veronica bullii |
| Knapweed, Black | Centaurea nigra |
| Knapweed, Spotted | Centaurea stoebe ssp. micranthos |
| Knockaway | Ehretia anacua |
| Knotweed, Japanese | Reynoutria japonica |
| Koa | Acacia koa |
| Koki'o | Kokia drynarioides |
| Kokolau | Bidens hawaiensis |
| Kolea lau nui | Myrsine lessertiana |
| Ko'oloa 'ula | Abutilon menziesii |
| Kupaoa | Dubautia scabra |
| Labrador Tea | Rhododendron groenlandicum |
| Ladies Tresses, Great Plains | Spiranthes magnicamporum |
| Ladies Tresses, Hooded | Spiranthes romanzoffiana |
| Ladies Tresses, Nodding | Spiranthes cernua |
| Ladies Tresses, Northern Slender | Spiranthes lacera |
| Ladies Tresses, Shining | Spiranthes lucida |
| Ladies Tresses, Sphinx | Spiranthes incurva |
| Lady Fingers | Anthyllis vulneraria |
| Ladyslipper, Greater Yellow | Cypripedium parviflorum var. pubescens |
| Ladyslipper, Lesser Yellow | Cypripedium parviflorum var. makasin |
| Ladyslipper, Mountain | Cypripedium montanum |
| Ladyslipper, Pink | Cypripedium acaule |
| Ladyslipper, Ramshead | Cypripedium arietinum |
| Ladyslipper, Showy | Cypripedium reginae |
| Ladyslipper, Sparrowegg | Cypripedium passerinum |
| Ladyslipper, Spotted | Cypripedium guttatum |
| Ladyslipper, White | Cypripedium candidum |
| Lantana | Lantana camara |
| Lantana, Texas | Lantana x urticoides |
| Larch, Western | Larix occidentalis |
| Larkspur, Canyon | Delphinium nudicaule |
| Larkspur, Desert | Delphinium parishii |
| Larkspur, Dwarf | Delphinium tricorne |
| Larkspur, Kern County | Delphinium purpusii |
| Larkspur, Little | Delphinium bicolor |
| Larkspur, Low | Delphinium bicolor |
| Larkspur, Nuttall's | Delphinium nuttallianum |
| Larkspur, Red | Delphinium nudicaule |
| Larkspur, Royal | Delphinium variegatum |
| Larkspur, San Bernardino | Delphinium parryi |
| Larkspur, Sierra | Delphinium glaucum |
| Larkspur, Slim | Delphinium depauperatum |
| Larkspur, Western | Delphinium x occidentale |
| Lasiandra | Tibouchina urvilleana |
| Laurel, Alpine | Kalmia microphylla |
| Laurel, Bog | Kalmia polifolia |
| Laurel, Bog | Kalmia microphylla |
| Laurel, Mountain | Kalmia latifolia |
| Laurel, Sheep (Lambkill) | Kalmia angustifolia |
| Lavender, Desert | Condea emoryi |
| Laxflower | Baileya pauciradiata |
| Lead Plant | Amorpha canescens |
| Leadtree, White | Leucaena leucocephala |
| Leafcup, Whiteflower | Polymnia canadensis |
| Leatherflower | Clematis hirsutissima |
| Leatherleaf | Chamaedaphne calyculata |
| Leek, Wild | Allium tricoccum |
| Lemonadeberry | Rhus integrifolia |
| Lespedeza, Chinese | Lespedeza cuneata |
| Lichen, Christmas | Herpothallon rubrocinctum |
| Lichen, Disc | Buellia erubescens |
| Lichen, Reindeer | Cladina sp. |
| Lichen, Wolf | Letharia vulpina |
| Lily of the Valley | Convallaria majalis |
| Lily of the Valley, False | Maianthemum dilatatum |
| Lily, Chocolate | Fritillaria camschatcensis |
| Lily, Chocolate | Fritillaria biflora |
| Lily, Clinton's | Clintonia umbellatum |
| Lily, Columbian | Lilium columbianum |
| Lily, Corn | Veratrum viride |
| Lily, Desert | Hesperocallis undulata |
| Lily, Globe | Calochortus albus |
| Lily, Hasta | Hasta sp. |
| Lily, Kamchatka | Fritillaria camschatcensis |
| Lily, Kellogg's | Lilium kelloggii |
| Lily, Leopard | Lilium pardalinum |
| Lily, Michigan | Lilium michiganense |
| Lily, Prairie | Lilium philadelphicum var. andinum |
| Lily, Prairie | Zephyranthes drummondii |
| Lily, Sego | Calochortus nuttallii |
| Lily, Spider | Crinum asiaticum |
| Lily, Striped Barbados | Hippeastrum striatum |
| Lily, Surprise | Lycoris squamigera |
| Lily, Swamp | Crinum americanum |
| Lily, Wood | Lilium philadelphicum var. philadelphicum |
| Lindley's Silverpuffs | Uropappus lindleyi |
| Lip Fern, Coville's | Myriopteris covillei |
| Little Prince's Pine | Chimaphila menziesii |
| Live-for-ever, Canyon | Dudleya cymosa |
| Live-for-ever, Powdery | Dudleya farinosa |
| Lobelia, Glade | Lobelia glandulosa |
| Lobelia, Great Blue | Lobelia siphilitica |
| Lobelia, Kalm's | Lobelia kalmii |
| Lobelia, Pale Spiked | Lobelia spicata |
| Lobster Claw, Hanging | Heliconia rostrata |
| Locoweed | Astragalus sp. |
| Locoweed, Field | Oxytropis campestris |
| Locoweed, Pomona | Astragalus pomonensis |
| Locoweed, Scarlet | Astragalus coccineus |
| Locoweed, Woolly | Astragalus mollissimus |
| Lomatium, Common | Lomatium utriculatum |
| Lomatium, Shiny | Lomatium lucidum |
| Loosestrfe, Whorled | Lysimachia quadrifolia |
| Loosestrife, Fringed | Lysimachia ciliata |
| Loosestrife, Lance-leaved | Lysimachia lanceolata |
| Loosestrife, Narrow-leaved | Lysimachia quadriflora |
| Loosestrife, Purple | Lythrum salicaria |
| Loosestrife, Tufted | Lysimachia thyrsiflora |
| Loosestrife, Winged | Lythrum alatum |
| Lopseed, American | Phryma leptostachya |
| Lotus, Coast | Hosackia gracilis |
| Lousewort, Bird's-Beak | Pedicularis ornithorhyncha |
| Lousewort, Capitate | Pedicularis capitata |
| Lousewort, Coiled | Pedicularis contorta |
| Lousewort, Elephanthead | Pedicularis groenlandica |
| Lousewort, Labrador | Pedicularis labradorica |
| Lousewort, Sickletop | Pedicularis racemosa |
| Lousewort, Sudetic | Pedicularis sudetica |
| Lousewort, Towering | Pedicularis bracteosa |
| Lousewort, Whorled Leaf | Pedicularis verticillata |
| Lousewort, Woolly | Pedicularis lanata |
| Lovegrass, Purple | Eragrostis spectabilis |
| Lucky Nut | Cascabela thevetia |
| Lungwort, Trumpet | Mertensia longiflora |
| Lupine | Lupinus sp. |
| Lupine, Arizona | Lupinus arizonicus |
| Lupine, Arroyo | Lupinus succulentus |
| Lupine, Big Leaf | Lupinus polyphyllus |
| Lupine, Chamisso Bush | Lupinus chamissonis |
| Lupine, Coulter's | Lupinus sparsiflorus |
| Lupine, Desert | Lupinus shockleyi |
| Lupine, Dove | Lupinus bicolor |
| Lupine, Dwarf | Lupinus lepidus |
| Lupine, Fragrant Dune | Lupinus chamissonis |
| Lupine, Hall's Bush | Lupinus excubitus var. hallii |
| Lupine, Longspur | Lupinus arbustus |
| Lupine, Miniature | Lupinus bicolor |
| Lupine, Nootka | Lupinus nootkatensis |
| Lupine, Pacific | Lupinus lepidus |
| Lupine, Scarlet | Lupinus concinnus |
| Lupine, Silky | Lupinus sericeus |
| Lupine, Silver Bush | Lupinus albifrons var. collinus |
| Lupine, Silver Bush | Lupinus albifrons |
| Lupine, Silvery | Lupinus argenteus |
| Lupine, Stinging | Lupinus hirsutissimus |
| Lupine, Subalpine | Lupinus arcticus ssp. subalpinus |
| Lupine, Sulphur | Lupinus sulphureus |
| Lupine, Wild | Lupinus perennis |
| Lupine, Yellow Bush | Lupinus arboreus |
| Madrone, Pacific | Arbutus menziesii |
| Madrone, Texas | Arbutus xalapensis |
| Magnolia, Bigleaf | Magnolia macrophylla |
| Mallow, Clustered Poppy | Callirhoe triangulata |
| Mallow, Glade | Napaea dioica |
| Mallow, High | Malva sylvestris |
| Mallow, Musk | Malva moschata |
| Mallow, Venice | Hibiscus trionum |
| Mallow, Vervain | Malva alcea |
| Mallow, Wax | Malvaviscus arboreus var. drummondii |
| Mamane | Sophora chrysophylla |
| Mangrove, White | Laguncularia racemosa |
| Manzanita, Pointleaf | Arctostaphylos pungens |
| Ma'o hau hele | Hibiscus brackenridgei |
| Maple, Bigleaf | Acer macrophyllum |
| Maple, Mountain | Acer spicatum |
| Maple, Norway | Acer platanoides |
| Maple, Red | Acer rubrum |
| Maple, Striped | Acer pensylvanicum |
| Maple, Sugar | Acer saccharum |
| Maple, Vine | Acer circinatum |
| Mariposa Lily, Oakland | Calochortus umbellatus |
| Mariposa Lily, Sagebrush | Calochortus macrocarpus |
| Mariposa Lily, Santa Catalina | Calochortus catalinae |
| Mariposa Lily, Splendid | Calochortus splendens |
| Mariposa Lily, White | Calochortus eurycarpus |
| Mariposa Lily, Winding | Calochortus flexuosus |
| Marlberry | Ardisia escallonioides |
| Marram Grass | Ammophila breviligulata |
| Marsh Marigold | Caltha palustris |
| Marsh Marigold, Mountain | Caltha leptosepala |
| Marsh Vetchling | Lathyrus palustris |
| May Apple | Podophyllum peltatum |
| May Lily, Pacific | Maianthemum dilatatum |
| Mayflower, Canada | Maianthemum canadense |
| Mazapan | Malvaviscus penduliflorus |
| Meadow Beauty | Rhexia virginica |
| Meadow Parsnip | Thaspium trifoliatum |
| Meadow Parsnip, Hairy-jointed | Thaspium barbinode |
| Meadow Rue, Early | Thalictrum dioicum |
| Meadow Rue, Purple-Stemmed | Thalictrum dasycarpum |
| Meadow Rue, Tall | Thalictrum pubescens |
| Meadowfoam, Rose-Veined | Limnanthes douglasii ssp. rosea |
| Meadowsweet | Spiraea alba |
| Meadowsweet, Rose | Spiraea splendens |
| Menziesia, Rusty | Rhododendron menziesii |
| Mescal Bean | Dermatophyllum secundiflora |
| Mexican Olive | Cordia boissieri |
| Miami Mist | Phacelia purshii |
| Mickey Mouse Bush | Ochna serrulata |
| Milk Cap, Indigo | Lactarius indigo |
| Milk Vetch, Hairy Arctic | Astragalus umbellatus |
| Milkmaids | Cardamine californica |
| Milk-vetch | Astragalus sp. |
| Milkvetch, Borrego | Astragalus lentiginosus var. borreganus |
| Milkvetch, Canadian | Astragalus canadensis |
| Milk-vetch, Layne's | Astragalus layneae |
| Milkvetch, Ozark | Astragalus distortus var. distortus |
| Milkvetch, Palmer's | Astragalus Palmeri |
| Milkvetch, Small-flowered | Astragalus nuttallianus |
| Milkvetch, Tundra | Astragalus umbellatus |
| Milkvetch, Woolly | Astragalus mollissimus |
| Milkweed, Clasping | Asclepias amplexicaulis |
| Milkweed, Common | Asclepias syriaca |
| Milkweed, Hairy | Funastrum hirtellum |
| Milkweed, Poke | Asclepias exalta |
| Milkweed, Prairie | Asclepias sullivantii |
| Milkweed, Purple | Asclepias purpurascens |
| Milkweed, Rambling | Funastrum hirtellum |
| Milkweed, Sand | Asclepias amplexicaulis |
| Milkweed, Short Green | Asclepias viridiflora |
| Milkweed, Swamp | Asclepias incarnata |
| Milkweed, Tall Green | Asclepias hirtella |
| Milkweed, White-stemmed | Asclepias albicans |
| Milkweed, Whorled | Asclepias verticillata |
| Milkweed, Wooly | Asclepias lanuginosa |
| Milkwort, Cross-leaved | Polygala cruciata |
| Milkwort, Field | Polygala sanguinea |
| Milkwort, Purple | Polygala polygama |
| Milkwort, White | Polygala alba |
| Milkwort, Whorled | Polygala verticillata |
| Milkwort, Yellow | Polygala rugelii |
| Milo | Thespesia populnea |
| Mint, Common Mountain | Pycnanthemum virginianum |
| Mint, Horse | Monarda punctata |
| Mint, Wild | Mentha canadensis |
| Mistflower, Blue | Conoclinium coelestinum |
| Mistletoe, Big-leaved | Phoradendron serotinum |
| Mistletoe, California Mesquite | Phoradendron californicum |
| Mitrewort | Mitella diphylla |
| Mock Orange, Wild | Philadelphus lewisii |
| Moneywort | Lysimachia nummularia |
| Monkeyflower | Mimulus ringens |
| Monkeyflower, Bigelow | Diplacus bigelovii |
| Monkeyflower, Coastal | Erythranthe dentata |
| Monkeyflower, Death Valley Rock | Diplacus rupicola |
| Monkeyflower, Kellogg's | Diplacus kelloggii |
| Monkeyflower, Primrose | Erythranthe primuloides |
| Monkeyflower, Purple | Erythranthe lewisii |
| Monkeyflower, Roundleaf | Erythranthe glabrata |
| Monkeyflower, Seep Spring | Erythranthe guttata |
| Monkeyflower, Sticky | Diplacus aurantiacus ssp. aurantiacus |
| Monkeyflower, Tooth-leaved | Erythranthe dentata |
| Monkeyflower, Wide Throat Yellow | Diplacus brevipes |
| Monkeyflower, Yellow Creeping | Erythranthe primuloides |
| Monkshood, Columbian | Aconitum columbianum |
| Monkshood, Larkspurleaf | Aconitum delphiniifolium |
| Monkshood, Northern | Aconitum noveboracense |
| Montbretia | Crocosmia x crocosmiiflora |
| Morel, Black | Morchella angusticeps |
| Morel, White | Morchella americana |
| Mormon Tea | Ephedra sp. |
| Mormon Tea | Ephedra viridis |
| Morning Glory | Ipomoea sp. |
| Morning Glory, Beach | Ipomoea pes-caprae |
| Morning Glory, Beach | Calystegia soldanella |
| Morning Glory, Oceanblue | Ipomoea indica |
| Morning-glory, Serpentine | Calystegia collina ssp. oxyphylla |
| Morning-glory, Southern Cal. | Calystegia macrostegia |
| Moss, Common Haircap | Polytrichum commune |
| Moss, Dry Rock | Grimmia laevigata |
| Moss, Stairstep | Hylocomium splendens |
| Mountain Ash, American | Sorbus americana |
| Mountain Ash, European | Sorbus aucuparia |
| Mountain Ash, Greene's | Sorbus scopulina |
| Mountain Ash, Western | Sorbus sitchensis |
| Mountain Avens, Eight-petal | Dryas octopetala |
| Mountain Laurel, Texas | Dermatophyllum secundiflora |
| Mountain Mahogany, Littleleaf | Cercocarpus intricatus |
| Mountainheath, Pink | Phyllodoce empetriformis |
| Mouse Ears, Purple | Diplacus douglasii |
| Mulberry, Indian | Morinda citrifolia |
| Mule Ears | Wyethia angustifolia |
| Mule Ears, Northern | Wyethia amplexicaulis |
| Mule-Ears, Sunflower | Wyethia helianthoides |
| Mullein, Common | Verbascum thapsus |
| Mullein, Moth | Verbascum blattaria |
| Mustard, Bicolor | Nerisyrenia camporum |
| Mustard, Black | Brassica nigra |
| Mustard, Bladderpod | Physaria gordonii |
| Mustard, False | Eulobus californica |
| Mustard, Field | Brassica napus |
| Mustard, Longbeak Fiddle | Streptanthella longirostris |
| Mustard, Sahara | Brassica tournefortii |
| Nannyberry | Viburnum lentago |
| Naupaka, Mountain | Scaevola procera |
| Navarretia, Spiny | Navarretia leucocephala |
| Needlegrass, Purple | Nassella pulchra |
| Nettle, Horse | Agastache urticifolia |
| Nettle, Wood | Laportea canadensis |
| New Jersey Tea | Ceanothus americanus |
| New Jersey Tea, Inland | Ceanothus herbaceus |
| Nightshade, Mullein | Solanum donianum |
| Nightshade, Purple | Solanum xanti |
| Nightshade,Eastern Black | Solanum emulans |
| Ninebark | Physocarpus opulifolius |
| Nolina, Bigelow | Nolina bigelovii |
| Nolina, Parry | Nolina parryi |
| Noni | Morinda citrifolia |
| Nut Rush, Low | Scleria verticillata |
| Nut Sedge, Long-scaled | Cyperus strigosus |
| Oak, Black | Quercus velutina |
| Oak, Blackjack | Quercus marilandica |
| Oak, Blue | Quercus douglasii |
| Oak, Bur | Quercus macrocarpa |
| Oak, Engelmann's | Quercus engelmannii |
| Oak, Hill's | Quercus ellipsoidalis |
| Oak, Live | Quercus virginiana |
| Oak, Northern Pin | Quercus ellipsoidalis |
| Oak, Oregon White | Quercus garryana |
| Oak, Red | Quercus rubra |
| Oakfern, Common | Gymnocarpium dryopteris |
| Oakfern, Pacific | Gymnocarpium disjunctum |
| Obedient Plant | Physostegia virginiana |
| Ocotillo | Fouquieria splendens |
| Ohelo 'ai | Vaccinium reticulatum |
| Ohi'a Lehua | Metrosideros polymorpha |
| Onion, Cascade | Allium cratericola |
| Onion, Coast | Allium dichlamydeum |
| Onion, Drummond | Allium drummondii |
| Onion, Fringed | Allium fimbriatum |
| Onion, Nodding | Allium cernuum |
| Onion, Olympic | Allium crenulatum |
| Onion, Red-skinned | Allium haematochiton |
| Onyxflower | Achyronychia cooperi |
| Orchid, Bamboo | Arundina graminifolia |
| Orchid, Club-spur | Platanthera clavellata |
| Orchid, Cultivated Hybrid | Orchidaceae sp. |
| Orchid, Cymbidium | Cymbidium sp. |
| Orchid, Dendrobium | Dendrobium glomeratum |
| Orchid, Dragon's Mouth | Arethusa bulbosa |
| Orchid, Five-Star | Epidendrum radicans |
| Orchid, Grass Pink | Calopogon tuberosus |
| Orchid, Moth | Phalaenopsis sp. |
| Orchid, Prairie White Fringed | Platanthera leucophaea |
| Orchid, Ragged Fringed | Platanthera lacera |
| Orchid, Stream | Epipactis gigantea |
| Orchis, Showy | Galearis spectabilis |
| Oregano | Origanum vulgare |
| Oregon Grape | Berberis repens |
| Osage Orange | Maclura pomifera |
| Owl's Clover, Dense-flowered | Castilleja densiflora |
| Owl's Clover, Purple | Castilleja exserta |
| Owl's Clover, Yellow | Castilleja campestris ssp. campestris |
| Oxeye | Heliopsis helianthoides |
| Pagoda-plant, Downy | Blephilia ciliata |
| Paintbrush, Alaska | Castilleja unalaschcensis |
| Paintbrush, Cusick's | Castilleja cusickii |
| Paintbrush, Desert | Castilleja angustifolia |
| Paintbrush, Elegant | Castilleja elegans |
| Paintbrush, Field | Castilleja arvensis |
| Paintbrush, Indian | Castilleja affinis |
| Paintbrush, Indian | Castilleja coccinea |
| Paintbrush, Pink | Castilleja sessiliflora |
| Paintbrush, Texas | Castilleja indivisa |
| Paintbrush, Vernal Pool | Castilleja campestris ssp. campestris |
| Paintbrush, Wavy-leaved | Castilleja applegatei |
| Paintbrush, Woolly | Castilleja foliolosa |
| Paintbrush, Wyoming | Castilleja linariifolia |
| Paintedcup, Downy | Castilleja sessiliflora |
| Painted-Cup, Downy Yellow | Castilleja sessiliflora |
| Palafox, Texas | Palafoxia texana |
| Paleface | Hibiscus denudatus |
| Palm, Areca | Dypsis lutescens |
| Palm, Fan | Pritchardia sp. |
| Palmetto, Saw | Serenoa repens |
| Palo Verde | Parkinsonia sp. |
| Papaya | Carica papaya |
| Paperflower, Greenstem | Psilostrophe sparsiflora |
| Paperflower, White-stemmed | Psilostrophe cooperi |
| Paperflower, Woolly | Psilostrophe tagetina |
| Parasol Whitetop | Doellingeria umbellata |
| Partridge Pea | Chamaecrista fasciculata var. fasciculata |
| Partridge Pea, Sensitive | Chamaecrista nictitans |
| Partridgeberry | Mitchella repens |
| Partridge-foot | Luetkea pectinata |
| Pasqueflower, Eastern | Pulsatilla nuttalliana |
| Pasqueflower, Western | Pulsatilla occidentalis |
| Pasqueflower, White | Pulsatilla occidentalis |
| Passion Fruit | Passiflora edulis |
| Pawpaw | Asimina triloba |
| Pea, Aspen | Lathyrus laetivirens |
| Pea, Beach | Lathyrus japonicus |
| Pea, Cream | Lathyrus ochroleucus |
| Pea, Pacific | Lathyrus vestitus |
| Pea, San Diego | Lathyrus vestitus var. alefeldii |
| Pea, Sierra | Lathyrus nevadensis |
| Pea, Stiff | Lathyrus rigidus |
| Pea, Veiny | Lathyrus venosus |
| Pearlflower | Heterocentron subtriplinervium |
| Pelotazo, Sweet | Abutilon incanum |
| Pennywort, Virginia | Obolaria virginica |
| Penstemon | Penstemon sp. |
| Penstemon, Bush | Penstemon fruticosus |
| Penstemon, Davidson's | Penstemon davidsonii |
| Penstemon, Desert | Penstemon pseudospectabilis |
| Penstemon, Eaton's | Penstemon eatonii |
| Penstemon, Firecracker | Penstemon eatonii |
| Penstemon, Hairy | Penstemon hirsutus |
| Penstemon, Lilac | Penstemon gracilis |
| Penstemon, Littleflower | Penstemon procerus |
| Penstemon, Meadow | Penstemon rydbergii |
| Penstemon, Parry | Penstemon parryi |
| Penstemon, Scabland | Penstemon deustus |
| Penstemon, Sharpleaf | Penstemon acuminatus |
| Penstemon, Shrubby | Penstemon fruticosus |
| Penstemon, Slender | Penstemon gracilis |
| Penstemon, Taper-Leaved | Penstemon attenuatus |
| Penstemon, Tolmie's | Penstemon procerus var. tolmiei |
| Pepperbush | Croton humilis |
| Peppertree, Brazilian | Schinus terebinthifolius |
| Pepperweed, Virginia | Lepidium virginicum |
| Periwinkle, Common | Vinca minor |
| Phacelia, Caltha-leafed | Phacelia calthifolia |
| Phacelia, Caterpillar | Phacelia cicutaria var. hispida |
| Phacelia, Cleftleaf | Phacelia crenulata |
| Phacelia, Fernleaf | Phacelia bipinnatifida |
| Phacelia, Forest | Phacelia bipinnatifida |
| Phacelia, Fremont's | Phacelia fremontii |
| Phacelia, Fringed | Phacelia fimbriata |
| Phacelia, Hiddenflower | Phacelia cryptantha |
| Phacelia, Lace-Leaf | Phacelia distans |
| Phacelia, Parry's | Phacelia parryi |
| Phacelia, Pope's | Phacelia popei |
| Phacelia, Purple | Phacelia bipinnatifida |
| Phacelia, Silky | Phacelia sericea |
| Phacelia, Skyblue | Phacelia coerulea |
| Phlox, Blue | Phlox divaricata |
| Phlox, Cleft Sand | Phlox bifida |
| Phlox, Creeping | Phlox stolonifera |
| Phlox, Flowery | Phlox multiflora |
| Phlox, Garden | Phlox paniculata |
| Phlox, Long-leaved | Phlox longifolia |
| Phlox, Marsh | Phlox glaberrima |
| Phlox, Northern | Phlox adsurgens |
| Phlox, Prairie | Phlox pilosa |
| Phlox, Rocky Mountain | Phlox multiflora |
| Phlox, Spreading | Phlox diffusa |
| Phlox, Spreading | Phlox diffusa |
| Phlox, Zion | Phlox jonesii |
| Pholiota, Golden | Pholiota aurivella |
| Pickerelweed | Pontederia cordata |
| Pickleweed | Batis maritima |
| Pincushion, Desert | Chaenactis fremontii |
| Pincushion, White | Chaenactis artemisiifolia |
| Pincushion, Yellow | Chaenactis glabriuscula |
| Pine, Beach | Pinus contorta var. contorta |
| Pine, Gray | Pinus sabiniana |
| Pine, Great Basin Bristlecone | Pinus longaeva |
| Pine, Jack | Pinus banksiana |
| Pine, Lodgepole | Pinus contorta var. latifolia |
| Pine, Longleaf | Pinus palustris |
| Pine, Norfolk Island | Araucaria heterophylla |
| Pine, Ponderosa | Pinus ponderosa |
| Pine, Slash | Pinus elliottii |
| Pine, Two-Needle Pinyon | Pinus edulis |
| Pine, White | Pinus strobus |
| Pine, Whitebark | Pinus albicaulis |
| Pineapple | Ananas comosus |
| Pinesap | Monotropa hypopithys |
| Pink Plumes | Bistorta plumosa |
| Pinkfairies | Clarkia pulchella |
| Pinklady | Heterotis rotundifolia |
| Pinks, California Indian | Silene laciniata ssp. californica |
| Pinks, Fire | Silene virginica |
| Pinks, Fringed Indian | Silene laciniata |
| Pipes | Equisetum fluviatile |
| Pipewort | Eriocaulon aquaticum |
| Pipsissewa | Chimaphila umbellata |
| Pitcher Plant | Sarracenia purpurea |
| Pitcher Plant, California | Darlingtonia californica |
| Pitcher Plant, Hooded | Sarracenia minor |
| Pitcher Plant, Parrot | Sarracenia psittacina |
| Pixie-cup, Red-fruited | Cladonia pleurota |
| Plantain, Woolly | Plantago patagonica |
| Plum, American | Prunus americana |
| Plum, Chickasaw | Prunus mexicana |
| Plumbago | Plumbago auriculata |
| Plumeria | Plumeria sp. |
| Poison Ivy | Toxicodendron radicans ssp. radicans |
| Poison Ivy, Western | Toxicodendron rydbergii |
| Poison Oak | Toxicodendron diversilobum |
| Pokeweed | Phytolacca americana |
| Polypody, California | Polypodium californicum |
| Polypody, Rock | Polypodium virginianum |
| Pond Lily, Yellow | Nuphar advena |
| Pondweed, Common | Potamogeton natans |
| Popcorn Flower | Cryptantha sp. |
| Popcorn Flower, Rusty | Plagiobothrys nothofulvus |
| Poplar, Tulip | Liriodendron tulipifera |
| Poppy, California | Eschscholzia californica |
| Poppy, Celandine | Stylophorum diphyllum |
| Poppy, Desert | Eschscholzia parishii |
| Poppy, Desert Gold | Eschscholzia glyptosperma |
| Poppy, Lobb's | Eschscholzia lobbii |
| Poppy, Matilija | Romneya coulteri |
| Poppy, Parish's | Eschscholzia parishii |
| Poppy, Prickly | Argemone munita |
| Poppy, Pygmy Golden | Eschscholzia minutiflora |
| Poppy, Tree | Dendromecon rigida |
| Poppy, Tufted | Eschscholzia caespitosa |
| Porterweed, Blue | Stachytarpheta jamaicensis |
| Portia Tree | Thespesia populnea |
| Prairie Bells | Fritillaria liliacea |
| Prairie Clover, Purple | Dalea purpurea |
| Prairie Clover, White | Dalea candida |
| Prairie Dock | Silphium terebinthinaceum |
| Prairie Flax | Linum lewisii |
| Prairie Smoke | Geum triflorum |
| Pretty Face | Triteleia ixioides |
| Prickly Ash | Zanthoxylum americanum |
| Prickly Lettuce | Lactuca serriola |
| Prickly Phlox | Linanthus californicus |
| Prickly-Pear, Brittle | Opuntia fragilis |
| Prickly-Pear, Desert | Opuntia engelmannii |
| Prickly-Pear, Eastern | Opuntia cespitosa |
| Prickly-Pear, Hair-spine | Opuntia polyacantha |
| Prickly-Pear, Low | Opuntia humifusa |
| Prickly-Pear, Plains | Opuntia polyacantha |
| Prickly-Pear, Plains | Opuntia macrorhiza |
| Prickly-Pear, Santa Rita | Opuntia macrocentra var. macrocentra |
| Prickly-Pear, Western | Opuntia littoralis |
| Primrose, Arctic | Primula mistassinica |
| Primrose, Mistassini | Primula mistassinica |
| Primrose, Pale | Camissoniopsis pallida |
| Primrose-willow, Peruvian | Ludwigia peruviana |
| Princess Flower | Tibouchina urvilleana |
| Puccoon, Fringed | Lithospermum incisum |
| Puccoon, Hairy | Lithospermum caroliniense var.croceum |
| Puccoon, Hoary | Lithospermum canescens |
| Pukiawe | Leptecophylla tameiameiae |
| Purple Mat | Nama demissa |
| Pussy Ears | Calochortus tolmiei |
| Pussy Toes | Antennaria plantaginifolia |
| Pussy Toes, Field | Antennaria neglecta |
| Pussytoes, Rosy | Antennaria rosea |
| Putty Root | Aplectrum hyemale |
| Pyrola, One-flowered | Moneses uniflora |
| Pyrola, Pink | Pyrola asarifolia |
| Queen-Anne's Lace | Daucus carota |
| Queen-Cup | Clintonia uniflora |
| Queen-of-the-Prairie | Filipendula rubra |
| Quinine, Wild | Parthenium integrifolium |
| Rabbit Brush | Chrysothamnus sp. |
| Rabbit Tobacco, Two-color | Pseudognaphalium biolettii |
| Rabbitbrush, Rubber | Ericameria nauseosa |
| Ragweed, Common | Ambrosia artemisiifolia |
| Ragweed, Giant | Ambrosia trifida |
| Ragwort, Balsam | Packera paupercula |
| Ragwort, Golden | Packera aurea |
| Ragwort, Madagascar | Senecio madagascariensis |
| Ragwort, Roundleaf | Packera obovata |
| Ragwort, Small Black-tipped | Senecio lugens |
| Ragwort, Tansy | Jacobaea vulgaris |
| Ragwort, Texas | Senecio ampullaceus |
| Rain-Lily | Zephyranthes drummondii |
| Rasberry, Strawberryleaf | Rubus pedatus |
| Raspberry, Black | Rubus occidentalis |
| Raspberry, Common Red | Rubus idaeus |
| Raspberry, Dwarf Red | Rubus pubescens |
| Raspberry, Purple Flowering | Rubus odoratus |
| Ratany, Littleleaf | Krameria erecta |
| Rattle Pod, Smooth | Crotalaria pallida |
| Rattlebox, Smooth | Crotalaria pallida |
| Rattlesnake Master | Eryngium yuccifolium |
| Rattlesnake Plantain | Goodyera pubescens |
| Rattlesnake Plantain, Western | Goodyera oblongifolia |
| Red Maids | Calandrinia menziesii |
| Redbud | Cercis canadensis |
| Redbud, Western | Cercis orbiculata |
| Redcedar, Eastern | Juniperus virginiana var. virginiana |
| Redcedar, Western | Thuja plicata |
| Redwood, Coast | Sequoia sempervirens |
| Rein Orchid, Royal | Platanthera transversa |
| Reindeer Moss | Cladonia sp. |
| Rein-Orchid, Tall White | Platanthera dilatata |
| Rhododendron, Pacific | Rhododendron macrophyllum |
| Rhododendron, White | Rhododendron albiflorum |
| Rhodora | Rhododendron canadense |
| Robin's Plantain | Erigeron pulchellus |
| Rock Harlequin | Corydalis sempervirens |
| Rock Lettuce | Dudleya cymosa |
| Rock Pea, Desert | Acmispon rigidus |
| Rockcress, Missouri | Boechera missouriensis |
| Rock-Daisy, Emory's | Perityle emoryi |
| Rocket, Purple | Iodanthus pinnatifidus |
| Rockflower, Ragged | Crossosoma bigelovii |
| Rocknettle, Desert | Eucnide urens |
| Rockrose | Crocanthemum bicknellii |
| Rockrose, Common | Crocanthemum canadense |
| Rose Gentian | Sabatia angularis |
| Rose Pogonia | Pogonia ophioglossoides |
| Rose, Common Wild | Rosa woodsii |
| Rose, Dwarf | Rosa gymnocarpa |
| Rose, Hawaiian | Osteomeles anthyllidifolia |
| Rose, Multiflora | Rosa multiflora |
| Rose, Pasture | Rosa carolina |
| Rose, Prairie | Rosa arkansana |
| Rose, Prickly | Rosa acicularis |
| Rose, Smooth | Rosa blanda |
| Rose, Swamp | Rosa palustris |
| Rose, Sweetbrier | Rosa rubiginosa |
| Rose, Wood | Rosa gymnocarpa |
| Rose, Wood's | Rosa woodsii |
| Rosebay, California | Rhododendron macrophyllum |
| Rosemallow, Halberd-Leaved | Hibiscus laevis |
| Rosemallow, Hawaiian Red | Hibiscus kokio |
| Rosemallow, Heartleaf | Hibiscus martianus |
| Rosemallow, Swamp | Hibiscus moscheutos |
| Rosinweed | Silphium integrifolium |
| Rosy Twisted Stalk | Streptopus lanceolatus |
| Rubber-Vine, Mangrove | Rhabdadenia biflora |
| Ruffle Lichen, Powdered | Parmotrema hypotropum |
| Rush, Dark Green | Scirpus atrovirens |
| Rush, Iris-leaved | Juncus xiphioides |
| Rush, Twig | Cladium mariscoides |
| Rush, Wicket Spike | Eleocharis rostellata |
| Russian Thistle | Salsola tragus |
| Sage, Azure Blue | Salvia azurea |
| Sage, Black | Salvia mellifera |
| Sage, Death Valley | Salvia funerea |
| Sage, Desert | Salvia dorrii |
| Sage, Kitchen | Salvia officinalis |
| Sage, Pitcher | Salvia azurea |
| Sage, Purple | Salvia dorrii ssp. mearnsii |
| Sage, Purple | Salvia dorrii |
| Sage, Scarlet | Salvia coccinea |
| Sage, Thistle | Salvia carduacea |
| Sage, Verde Valley | Salvia dorrii ssp. mearnsii |
| Sage, White | Salvia apiana |
| Sagebrush, White | Artemisia ludovicieana |
| Saguaro | Carnegiea gigantea |
| Salal | Gaultheria shallon |
| Salmonberry | Rubus spectabilis |
| Saltcedar | Tamarix ramosissima |
| Sand Verbena, Hairy | Abronia villosa |
| Sand Verbena, Snowball | Abronia fragrans |
| Sand Verbena, Yellow | Abronia latifolia |
| Sandbells | Nama hispida |
| Sandmat, Mexican | Euphorbia polycarpa |
| Sandwort, Arctic | Pseudocherleria macrocarpa |
| Sandwort, Brittle | Minuartia nuttallii |
| Sandwort, Mountain | Mononeuria groenlandica |
| Sandwort, Nuttall's | Minuartia nuttallii |
| Sandwort, Pitcher's | Mononeuria patula |
| Sandwort, Slender Mountain | Eremogone capillaris ssp. capillaris |
| Sandwort, Stiff | Minuartia michauxii |
| Sandwort, Stiff | Minuartia dawsonensis |
| Sandwort, Wood | Moehringia lateriflora |
| Sanicle, Purple | Sanicula bipinnatifida |
| Sanicle, Sharp-toothed | Sanicula arguta |
| Sarsaparilla, Bristly | Aralia hispida |
| Sarsaparilla, Wild | Aralia nudicaulis |
| Saskatoon | Amelanchier alnafolia |
| Sassafras | Sassafras albidum |
| Saw-wort, Narrowleaf | Saussurea angustifolia |
| Saxifrage, Brook | Micranthes odontoloma |
| Saxifrage, Palmer's | Micranthes palmeri |
| Saxifrage, Peak | Micranthes nidifica |
| Saxifrage, Red-stemmed | Micranthes lyallii |
| Saxifrage, Swamp | Micranthes pensylvanica |
| Saxifrage, Tolmie's | Micranthes tolmiei |
| Saxifrage, Tufted Alpine | Saxifraga caespitosa |
| Saxifrage, Yellow Spotted | Saxifraga bronchialis |
| Saxifrage, Yellowdot | Saxifraga bronchialis |
| Saxifrage. Early | Micranthes virginiensis |
| Scalebroom | Lepidospartum squamatum |
| Scarlet Beeblossom | Oenothera suffrutescens |
| Scarlet Bugler | Penstemon centranthifolius |
| Scarlet Pimpernel | Anagallis arvensis |
| Scorpion-Moss, Hooked | Scorpidium scorpioides |
| Scouring Rush | Equisetum hyemale |
| Scouring Rush, Small | Equisetum variegatum |
| Scouring-rush, Dwarf | Equisetum scirpoides |
| Scrambled Eggs | Corydalis aurea |
| Screwpine | Pandanus tectorius |
| Sea Dahlia | Leptosyne maritima |
| Sea-rocket, American | Cakile edentula |
| Sedge | Carex sp. |
| Sedge, Bog | Carex limosa |
| Sedge, Bottlebrush | Carex hystericina |
| Sedge, Bristly | Carex comosa |
| Sedge, Bristlystalked | Carex leptalea |
| Sedge, Capitate | Carex cephalophora |
| Sedge, Common Stiff | Carex tetanica |
| Sedge, Crested | Carex cristatella |
| Sedge, Dark-scaled | Carex buxbaumii |
| Sedge, Green Yellow | Carex viridula |
| Sedge, Hop | Carex lupulina |
| Sedge, Mud | Carex limosa |
| Sedge, Pennsylvania | Carex pensylvanica |
| Sedge, Porcupine | Carex hystericina |
| Sedge, Richardson's | Carex richardsonii |
| Sedge, Slender | Carex leptalea |
| Sedge, Star Fen | Carex sterilis |
| Sedge, Three-Way | Dulichium arundinaceum |
| Sedge, Tuckerman's | Carex tuckermanii |
| Sedge, Tussock | Carex stricta |
| Sedge, Waterfall's | Carex latebracteata |
| Selenia, Golden | Selenia aurea |
| Senna, American | Senna hebecarpa |
| Senna, Twinleaf | Senna bauhinioides |
| Sequoia, Giant | Sequoiadendron giganteum |
| Serviceberry, Common | Amelanchier arborea |
| Serviceberry, Inland | Amelanchier interior |
| Seven Sisters | Crinum americanum |
| Shadblow, Low | Amelanchier humilis |
| Shadbush, Alder-leaf | Amelanchier alnafolia |
| Shinleaf, Green | Pyrola chlorantha |
| Shinleaf, Wax Flower | Pyrola elliptica |
| Shootingstar | Primula meadia |
| Shootingstar, Alpine | Primula tetrandra |
| Shootingstar, Bonneville | Primula conjugens |
| Shootingstar, Dark Throated | Primula pauciflora var. pauciflora |
| Shootingstar, Desert | Primula conjugens |
| Shootingstar, French's | Primula frenchii |
| Shootingstar, Jeffrey's | Primula jeffreyi |
| Shootingstar, Jeweled | Primula fassettii |
| Shootingstar, Padre | Primula clevelandii |
| Shootingstar, Sierra | Primula jeffreyi |
| Shootingstar, Western | Primula pauciflora var. pauciflora |
| Sideoats Grama | Bouteloua curtipendula |
| Silverbell, Mountain | Halesia carolina |
| Silverhead | Blutaparon vermiculare |
| Silverleaf | Leucophyllum frutescens |
| Silverpuffs, Grassland | Stebbinsoseris heterocarpa |
| Silversword, Kaua'i | Wilkesia gymnoxiphium |
| Silverweed | Potentilla anserina |
| Single Delights | Moneses uniflora |
| Skullcap, Drummond's | Scutellaria drummondii |
| Skullcap, Heart-leaved | Scutellaria ovata |
| Skullcap, Mad Dog | Scutellaria lateriflora |
| Skullcap, Marsh | Scutellaria galericulata |
| Skullcap, Small | Scutellaria parvula |
| Skunk Cabbage | Symplocarpus foetidus |
| Sleepy Morning | Waltheria indica |
| Smartweed, Pennsylvania | Persicaria pensylvanica |
| Smartweed, Water | Persicaria amphibia |
| Smoke Tree, American | Cotinus obovatus |
| Smoketree | Psorothamnus spinosus |
| Snakecotton, Plains | Froelichia floridana |
| Snakeroot, Seneca | Polygala senega |
| Snakeroot, White | Ageratina altissima var. altissima |
| Snake's Head | Malacothrix coulteri |
| Snakeweed, Light-blue | Stachytarpheta jamaicensis |
| Snakewort | Conocephalum salebrosum |
| Snapdragon, Coulter's | Sairocarpus coulterianus |
| Snapdragon, Twining | Neogaerrhinum filipes |
| Snapdragon, Twining | Neogaerrhinum strictum |
| Sneezeweed | Helenium autumnale |
| Snow on the Mountain | Euphorbia marginata |
| Snowberry, Creeping | Gaultheria hispidula |
| Snowberry, Western | Symphoricarpos occidentalis |
| Soapwort | Saponaria officinalis |
| Solomon's Seal, Smooth | Polygonatum biflorum var. commutatum |
| Sorrel, Common Wood | Oxalis montana |
| Sorrel, Redwood | Oxalis oregana |
| Sorrel, Violet Wood | Oxalis violacea |
| Sorrel, Yellow Wood | Oxalis stricta |
| Sourbush | Pluchea sericea |
| Sourgrass | Oxalis stricta |
| Sourwood | Oxydendrum arboreum |
| Spanish Dagger | Yucca treculeana |
| Spanish Moss | Tillandsia usneoides |
| Spanish Needle | Palafoxia arida |
| Spanish Shawl | Heterotis rotundifolia |
| Spatterdock | Nuphar variegata |
| Spectacle-pod, California | Dithyrea californica |
| Speedwell, American Alpine | Veronica wormskjoldii |
| Speedwell, Common | Veronica officinalis |
| Speedwell, Cusick's | Veronica cusickii |
| Speedwell, European | Veronica beccabunga |
| Sphagnum, Low | Sphagnum compactum |
| Spicebush, Northern | Lindera benzoin |
| Spiderplant, Yellow | Peritoma lutea |
| Spiderwort | Tradescantia ohiensis |
| Spiderwort, Ernest's | Tradescantia ernestiana |
| Spiderwort, Long-stemmed | Tradescantia longipes |
| Spiderwort, Ozark Mountain | Tradescantia longipes |
| Spiderwort, Virginia | Tradescantia virginiana |
| Spike-moss, Rock | Selaginella rupestris |
| Spikenard, American | Aralia racemosa |
| Spikerush, Flat-stemmed | Eleocharis compressa |
| Spikerush, Prairie | Eleocharis compressa |
| Spiraea, False | Sorbaria sorbifolia |
| Spirea, Bridalwreath | Spiraea prunifolia |
| Spirea, Steven's | Spiraea stevenii |
| Spleenwort, Ebony | Asplenium platyneuron |
| Spleenwort, Maidenhair | Asplenium trichomanes |
| Spotted Ladysthumb | Persicaria maculosa |
| Spotted, Wintergreen | Chimaphila maculata |
| Spreading Fleabane | Erigeron divergens |
| Spring Beauty | Claytonia virginica |
| Spring Beauty, Alaska | Claytonia sarmentosa |
| Spring Beauty, Carolina | Claytonia caroliniana |
| Spring Beauty, Heart-leaved | Claytonia cordifolia |
| Spring Beauty, Siberian | Claytonia sibirica |
| Spring Beauty, Western | Claytonia lanceolata |
| Spruce, Black | Picea mariana |
| Spruce, Engelmann | Picea engelmannii |
| Spruce, Sitka | Picea sitchensis |
| Spruce, White | Picea glauca |
| Spurge, Flowering | Euphorbia corollata |
| Spurge, Leafy | Euphorbia virgata |
| Spurge, Red | Euphorbia cotinifolia |
| Spurge, Red-gland | Euphorbia melanadenia |
| Spurred Gentian, American | Halenia deflexa |
| Squill, Siberian | Othocallis siberica |
| Squirrel-corn | Dicentra canadensis |
| St. Johnswort, Common | Hypericum perforatum |
| St. Johnswort, Dwarf | Hypericum mutilum |
| St. Johnswort, Four-petal | Hypericum tetrapetalum |
| St. Johnswort, Great | Hypericum ascyron |
| St. Johnswort, Kalm's | Hypericum kalmianum |
| St. Johnswort, Larger Canadian | Hypericum mutilum |
| St. Johnswort, Marsh | Hypericum virginicum |
| St. Johnswort, Northern | Hypericum mutilum ssp.boreale |
| St. Johnswort, Orange Grass | Hypericum gentianoides |
| Starflower | Lysimachia borealis |
| Starflower, Arctic | Lysimachia europea ssp. arctica |
| Starflower, Broadleaf | Lysimachia latifolia |
| Starflower, Western | Lysimachia latifolia |
| Stargrass, Yellow | Hypoxis hirsuta |
| Star-tulip, Tomie | Calochortus tolmiei |
| Star-tulip, Yellow | Calochortus monophyllus |
| Starwort, Long-leaf | Stellaria longifolia |
| Steeplebush | Spiraea tomentosa |
| Stingbush, Desert | Eucnide urens |
| Stitchwort, Arctic | Cherleria arctica |
| Stitchwort, long-pod | Pseudocherleria macrocarpa |
| Stock, Garden | Matthiola incana |
| Stock, Hoary | Matthiola incana |
| Stonecrop, Broadleaf | Sedum spathulifolium |
| Stonecrop, Ditch | Penthorum sedoides |
| Stonecrop, Goldmoss | Sedum acre |
| Stonecrop, Ledge | Rhodiola integrifolia ssp. integrifolia |
| Stonecrop, Pacific | Sedum divergens |
| Stonecrop, Sierra | Sedella pumila |
| Stonecrop, Spearleaf | Sedum lanceolatum |
| Stonecrop, Wild | Sedum ternatum |
| Stoneseed, American | Lithospermum latifolium |
| Stoneseed, Showy | Lithospermum incisum |
| Stonewort, Common | Chara vulgaris |
| Stork's Bill | Erodium cicutarium |
| Storksbill, Texas | Erodium texanum |
| Strawberry Pear | Hylocereus undatus |
| Strawberry, Barren | Waldsteinia fragarioides |
| Strawberry, Beach | Fragaria chiloensis |
| Strawberry, Wild | Fragaria virginiana |
| Sugarbowls | Clematis hirsutissima |
| Sugarbush | Rhus ovata |
| Sumac, Aromatic | Rhus aromatica |
| Sumac, Poison | Toxicodendron vernix |
| Sumac, Shining | Rhus copallinum |
| Sumac, Smooth | Rhus glabra |
| Sumac, Staghorn | Rhus typhina |
| Sunbonnet, Lilac | Langloisia setosissima |
| Suncups, California | Eulobus californica |
| Suncups, Hairy | Camissoniopsis hirtella |
| Suncups, Southern | Camissoniopsis bistorta |
| Sundew, Round-leaved | Drosera rotundifolia |
| Sundew, Spatulate-leaved | Drosera intermedia |
| Sunflower, Common Woolly | Eriophyllum lanatum |
| Sunflower, Downy | Helianthus mollis |
| Sunflower, Dune | Helianthus petiolaris |
| Sunflower, false | Heliopsis helianthoides |
| Sunflower, Little | Helianthella uniflora |
| Sunflower, Oneflower | Helianthella uniflora |
| Sunflower, Plains | Helianthus petiolaris |
| Sunflower, Prairie | Helianthus pauciflorus |
| Sunflower, Sawtooth | Helianthus grosseserratus |
| Sunflower, Showy | Helianthus pauciflorus |
| Sunflower, Western | Helianthus occidentalis |
| Sunflower, Woodland | Helianthus divaricatus |
| Swamp Candles | Lysimachia terrestris |
| Sweet Cicely, American | Osmorhiza longistylis |
| Sweet Everlasting | Pseudognaphalium obtusifolium |
| Sweet Flag | Acorus americanus |
| Sweetgale | Myrica gale |
| Sweetshrub | Calycanthus floridus |
| Sweetspire, Virginia | Itea virginica |
| Sweetvetch, Alpine | Hedysarum alpinum |
| Sweetvetch, Northern | Hedysarum boreale ssp. mackenziei |
| Sweetvetch, Western | Hedysarum occidentale |
| Switchgrass | Panicum virgatum |
| Swordfern, Hawaiian | Nephrolepis exaltata ssp. Hawaiiensis |
| Swordfern, Western | Polystichum munitum |
| Sycamore, American | Platanus occidentalis |
| Sycamore, California | Platanus racemosa |
| Syringa | Philadelphus lewisii |
| Tamarack | Larix laricina |
| Tansy, Common | Tanacetum vulgare |
| Tansyaster | Dieteria asteroides |
| Tansyaster, Tanseyleaf | Machaeranthera tanacetifolia |
| Teasel, Common | Dipsacus follonum |
| Teasel, Cut-leaved | Dipsacus laciniatus |
| Thimbelweed, Yellow | Anemone richardsonii |
| Thimbleberry | Rubus parviflorus |
| Thimbleweed | Anemone cylindrica |
| Thimbleweed, Edwards Plateau | Anemone edwardsiana var. petraea |
| Thimbleweed, Tenpetal | Anemone berlandieri |
| Thistle, Bull | Cirsium vulgare |
| Thistle, Canada | Cirsium arvense |
| Thistle, Edible | Cirsium edule |
| Thistle, Elk | Cirsium scariosum |
| Thistle, Indian | Cirsium edule |
| Thistle, Meadow | Cirsium scariosum |
| Thistle, Nodding | Carduus nutans |
| Thistle, Pasture | Cirsium discolor |
| Thistle, Prairie | Cirsium pumilum var. hillii |
| Thistle, Sand Dune | Cirsium pitcheri |
| Thistle, Swamp | Cirsium muticum |
| Thistle, Wavy Leafed | Cirsium undulatum |
| Threeleaf Goldthread | Coptis trifolia |
| Thrift Seapink | Armeria maritima |
| Ti | Cordyline fruticosa |
| Tick Trefoil, Greenleaf | Desmodium intortum |
| Tick Trefoil, Hairy Bracted | Desmodium cuspidatum var. longifolium |
| Tick Trefoil, Hoary | Desmodium canescens |
| Tick Trefoil, Illinois | Desmodium illinoense |
| Tick Trefoil, Pointed | Hylodesmum glutinosum |
| Tick Trefoil, Sessile-Leaved | Desmodium sessilifolium |
| Tick Trefoil, Showy | Desmodium canadense |
| Tickseed, Purple-stemmed | Bidens connata |
| Toadflax, Blue | Nuttallanthus canadensis |
| Toadflax, Canada | Nuttallanthus canadensis |
| Toadflax, False | Comandra umbellata spp. umbellata |
| Toadflax, Pale False | Comandra umbellata spp. pallida |
| Toadflax, Texas | Nuttallanthus texanus |
| Toadshade | Trillium sessile |
| Toadshade, Yellow | Trillium luteum |
| Tobacco, Desert | Nicotiana obtusifolia |
| Tonella, Many-flowered | Tonella floribunda |
| Toothed Polypore, Violet | Trichaptum biforme |
| Toothleaf, Annual | Stillingia spinulosa |
| Toothwort, Broad-leaved | Cardamine diphylla |
| Toothwort, Cut-leaved | Cardamine concatenata |
| Toothwort, Large | Cardamine maxima |
| Toothwort, Slender | Cardamine angustata |
| Toyon | Heteromeles arbutifolia |
| Tree Fern | Cibotium sp. |
| Treecotton, Hawaii | Kokia drynarioides |
| Trefoil, Bird's Foot | Lotus corniculatus |
| Trefoil, Seaside Bird's Foot | Hosackia gracilis |
| Trefoil, Streambank Bird's-foot | Hosackia oblongifolia |
| Trillium, Catesby's | Trillium catesbaei |
| Trillium, Declined | Trillium flexipes |
| Trillium, Large-Flowered | Trillium grandiflorum |
| Trillium, Nodding | Trillium cernuum |
| Trillium, Ozark | Trillium pusillum var. ozarkanum |
| Trillium, Painted | Trillium undulatum |
| Trillium, Prairie | Trillium recurvatum |
| Trillium, Red | Trillium erectum |
| Trillium, Southern Red | Trillium sulcatum |
| Trillium, Sweet White | Trillium simile |
| Trillium, Vasey's | Trillium vaseyi |
| Trillium, Western | Trillium ovatum |
| Trillium, Yellow | Trillium luteum |
| Triteleia, Large-flowered | Triteleia grandiflora |
| Trout Lily, White | Erythronium albidum |
| Trout Lily, Yellow | Erythronium americanum |
| Troutlily, Yellow | Erythronium rostratum |
| Trumpet-Tree, Caribbean | Tabebuia aurea |
| Tubetongue | Justicia pilosella |
| Tuliptree | Liriodendron tulipifera |
| Tupelo | Nyssa aquatica |
| Turks Cap | Malvaviscus arboreus var. drummondii |
| Turpentine Broom | Thamnosma montana |
| Turtlehead | Chelone glabra |
| Turtleweed | Batis maritima |
| Twayblade, Green | Liparis loeselii |
| Twinberry, Coast | Lonicera involucrata var. ledebourii |
| Twinflower | Linnaea borealis |
| Twistedstalk, Claspleaf | Streptopus amplexifolius |
| Uhaloa | Waltheria indica |
| Ulei | Osteomeles anthyllidifolia |
| Uluhe | Dicranopteris linearis |
| Umbrellaleaf, American | Diphylleia cymosa |
| Utah Penstemon | Penstemon utahensis |
| Valerian, Captiate | Valeriana captitata |
| Valerian, Common | Valeriana edulis var. ciliata |
| Valerian, Garden | Valeriana officinalis |
| Valerian, Marsh | Valeriana uliginosa |
| Valerian, Sitka | Valeriana sitchensis |
| Valley Tassels | Castilleja attenuata |
| Velvet Leaf | Allowissadula holosericea |
| Velvet Turtleback | Psathyrotes ramosissima |
| Venus' Looking-glass, Clasping | Triodanis perfoliata |
| Vervain, Blue | Verbena hastata |
| Vervain, Dakota Mock | Glandularia bipinnatifida |
| Vervain, Hairy White | Verbena urticifolia |
| Vervain, Hoary | Verbena stricta |
| Vervain, Narrowleaf | Verbena simplex |
| Vervain, Rose Mock | Glandularia canadensis |
| Vervain, Southwestern Mock | Glandularia gooddingii |
| Vetchling, Pale | Lathyrus ochroleucus |
| Viburnum, Maple-leaved | Viburnum acerifolium |
| Vining Cow Pea | Macroptilium atropurpureum |
| Violet, Alaska | Viola langsdorffii |
| Violet, Aleutian | Viola langsdorffii |
| Violet, Arrow-leaved | Viola sagittata |
| Violet, Birdfoot | Viola pedata |
| Violet, Canada | Viola canadensis |
| Violet, Common Blue | Viola sororia |
| Violet, Dog | Viola labradorica |
| Violet, Evergreen | Viola sempervirens |
| Violet, Halberd-leaved | Viola hastata |
| Violet, Hookedspur | Viola adunca |
| Violet, Long-spurred | Viola rostrata |
| Violet, Marsh Blue | Viola cucullata |
| Violet, Northern White | Viola macloskeyi ssp. pallens |
| Violet, Nuttall's | Viola pubescens |
| Violet, Pioneer | Viola glabella |
| Violet, Prairie | Viola pedatifida |
| Violet, Redwood | Viola sempervirens |
| Violet, Sand | Viola sagittata |
| Violet, Sand | Viola adunca |
| Violet, Smooth Yellow | Viola glabella |
| Violet, Sweet White | Viola blanda |
| Violet, Three-lobed | Viola triloba |
| Violet, Western Dog | Viola adunca |
| Violet, Yellow | Viola pubescens |
| Viper's Bugloss | Echium vulgare |
| Virgin's Bower | Clematis virginiana |
| Wahoo | Euonymus atropurpureus |
| Wakerobin, Bashful | Trillium catesbaei |
| Wakerobin, Furrowed | Trillium sulcatum |
| Wakerobin, Jeweled | Trillium simile |
| Wakerobin, Ozark | Trillium pusillum var. ozarkanum |
| Wakerobin, Sweet | Trillium vaseyi |
| Wall Rocket | Diplotaxis muralis |
| Wallflower, Cascade | Erysimum arenicola |
| Wallflower, Western | Erysimum capitatum |
| Wally Basket | Triteleia laxa |
| Walnut, Indian | Aleurites moluccanus |
| Water Crowfoot, White | Ranunculus longirostris |
| Water Crowfoot, White | Ranunculus aquatilis |
| Water Hemlock | Cicuta bulbifera |
| Water Hemlock, Bulblet Bearing | Cicuta bulbifera |
| Water Hemlock, Spotted | Cicuta maculata |
| Water Hemlock, Western | Cicuta douglasii |
| Water Hemlock, Wispy | Cicuta bulbifera |
| Water Horehound, Common | Lycopus americanus |
| Water Lily, White | Nymphaea odorata |
| Water Pepper | Persicaria hydropiper |
| Water Pepper, Mild | Persicaria hydropiperoides |
| Water Plantain, Common | Alisma subcordatum |
| Water Plantain, Northern | Alisma triviale |
| Water Shield | Brasenia schreberi |
| Watercress | Nasturtium officinale |
| Waterleaf, Appendaged | Hydrophyllum appendiculatum |
| Waterleaf, Great | Hydrophyllum appendiculatum |
| Waterleaf, Pacific | Hydrophyllum tenuipes |
| Waterleaf, Virginia | Hydrophyllum virginianum var. virginianum |
| Waterleaf, Western | Hydrophyllum appendiculatum |
| Wavy Cloakfern | Astrolepis sinuata ssp. sinuata |
| Wawae'iole | Lycopodiella cernua |
| Wax Plant | Euphorbia antisyphilitica |
| Wedelia | Sphagneticola trilobata |
| Western Larkspur | Delphinium hesperium |
| Whipplea, common | Whipplea modesta |
| Whisk Fern | Psilotum nudum |
| Whiskerbrush | Leptosiphon ciliatus ssp. ciliatus |
| Whispering Bells | Emmenanthe penduliflora |
| White Cedar, Eastern | Thuja occidentalis |
| White Lettuce | Nabalus albus |
| White Lettuce, Glaucous | Nabalus racemosus |
| White Lettuce, Rough | Nabalus asper |
| Wild Calla | Calla palustris |
| Wild Carrot | Daucus carota |
| Wild Crocus | Tradescantia longipes |
| Wild Hollyhock, Streambank | Iliamna rivularis |
| Wild Indigo, Cream | Baptisia leucophaea |
| Wild Indigo, White | Baptisia lactea |
| Wild Lettuce | Lactuca canadensis |
| Wild Oats | Uvularia sessilifolia |
| Wild Pansy | Viola bicolor |
| Wild Petunia | Ruellia humilis |
| Wild Petunia, Parry's | Ruellia parryi |
| Wild Raisin | Viburnum nudum var. cassinoides |
| Wild Rhubarb, Alaska | Polygonum alaskanum |
| Wild Rye, Canada | Elymus canadensis |
| Willow | Salix sp. |
| Willow Herb, Cinnamon | Epilobium coloratum |
| Willow Herb, Fen | Epilobium leptophyllum |
| Willow, Arctic | Salix arctica |
| Willow, Beaked | Salix bebbiana |
| Willow, Bebb's | Salix bebbiana |
| Willow, Netleaf | Salix reticulata |
| Willow, Netted | Salix reticulata |
| Willow, Prairie | Salix humilis |
| Willow, Pussy | Salix discolor |
| Willow-herb, Hairy | Epilobium hirsutum |
| Windflower | Anemone parviflora |
| Wind-flower | Anemone berlandieri |
| Windflower, Columbian | Anemone deltoidea |
| Windmills | Allionia incarnata |
| Wingstem | Verbesina alternifolia |
| Winterberry, Common | Ilex verticillata |
| Wintercreeper | Euonymus fortunei |
| Wintergreen | Gaultheria procumbens |
| Wintergreen, Sidebells | Orthilia secunda |
| Wishbone-bush | Mirabilis laevis var. villosa |
| Witch Hazel | Hamamelis virginiana |
| Wolfberry, Anderson's | Lycium andersonii |
| Wolfberry, Carolina | Lycium carolinianum |
| Wolfberry, Torrey | Lycium torreyi |
| Wood Fern, Intermediate | Dryopteris intermedia |
| Wood Vetch | Vicia caroliniana |
| Woodfern, Marginal | Dryopteris marginalis |
| Woodrush, Hairy | Luzula acuminata |
| Woolgrass | Scirpus cyperinus |
| Woollystar, Desert | Eriastrum eremicum |
| Wormwood, Absinthe | Artemisia absinthium |
| Wormwood, Beach | Artemisia campestra ssp.caudata |
| Woundwort | Stachys palustris |
| Yam, Wild | Dioscorea villosa |
| Yarrow | Achillea millefolium |
| Yarrow, Golden | Eriophyllum confertiflorum |
| Yellow Alder | Turnera ulmifolia |
| Yellow Carpet | Blennosperma nanum |
| Yellow Cups | Chylismia brevipes |
| Yellow Pimpernel | Taenidia integerrima |
| Yellowbells | Fritillaria pudica |
| Yellow-eyed Grass | Xyris montana |
| Yerba Santa | Eriodictyon californicum |
| Yucca, Chaparral | Hesperoyucca whipplei |
| Yucca, Mohave | Yucca schidigera |
| Zion Milkvetch | Astragalus zionis |