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Taxon author: Nutt.

ITIS records citing taxon author "Nutt."
 
 Kingdom Animalia
  Abietinaria alexanderi Nutting, 1904 -- valid
  Abietinaria amphora Nutting, 1904 -- valid
  Abietinaria costata (Nutting, 1901) -- valid
  Abietinaria gracilis Nutting, 1904 -- valid
  Abietinaria kincaidi (Nutting, 1901) -- valid
  Abietinaria pulchra (Nutting, 1904) -- valid
  Acanella sibogae Nutting, 1910 -- valid
  Acanthoptilum album Nutting, 1909 -- valid
  Acanthoptilum annulatum Nutting, 1909 -- valid
  Aglaophenia dubia Nutting, 1900 -- valid
  Aglaophenia latirostris Nutting, 1900 -- valid
  Aglaophenia octocarpa Nutting, 1900 -- valid
  Aglaophenoides mammillatus (Nutting, 1900) -- invalid
  Aglaophenopsis distans Nutting, 1900 -- valid
  Aglaophenopsis verrilli Nutting, 1900 -- valid
  Amphisbetia kurilae (Nutting, 1904) -- valid
  Anokkostenostomum anops (Nuttycombe and Waters, 1938) -- invalid
  Anokkostenostomum pegephilum (Nuttycombe and Waters, 1938) -- invalid
  Anokkostenostomum pseudoacetabulum (Nuttycombe and Waters, 1935) -- invalid
  Anokkostenostomum tuberculosum (Nuttycombe and Waters, 1938) -- invalid
  Anokkostenostomum ventronephrium (Nuttycombe, 1932) -- invalid
  Antennularia americana Nutting, 1900 -- invalid
  Antennularia rugosa Nutting, 1900 -- invalid
  Balella mirabilis (Nutting, 1905) -- valid
  Bonneviella regia (Nutting, 1901) -- valid
  Bonneviella superba Nutting, 1915 -- valid
  Calibelemnon Nutting, 1908 -- valid
  Calibelemnon symmetricum Nutting, 1908 -- valid
  Callogorgia gilberti (Nutting, 1908) -- valid
  Campanularia brevicaulis Nutting, 1915 -- valid
  Campanularia ritteri Nutting, 1901 -- valid
  Campanulina rugosa Nutting, 1901 -- invalid
  Catenula confusa Nuttycombe, 1956 -- valid
  Catenula leptocephala Nuttycombe, 1956 -- valid
  Catharus ustulatus (Nuttall, 1840) -- valid -- grive ŕ dos olive, Swainson's Thrush, Zorzal de Swainson
  Catharus ustulatus ustulatus (Nuttall, 1840) -- valid
  Cladocarpus obliquus Nutting, 1900 -- valid
  Cladocarpus septatus Nutting, 1900 -- valid
  Clytia edwardsi (Nutting, 1901) -- invalid
  Clytia kincaidi (Nutting, 1899) -- valid
  Clytia minuta (Nutting, 1901) -- invalid
  Contopus cooperi (Nuttall, 1831) -- valid -- moucherolle ŕ côtés olive, Olive-sided Flycatcher
  Coryne brachiata Nutting, 1901 -- valid
  Cyclomuricea Nutting, 1908 -- valid
  Cyclomuricea flabellata Nutting, 1908 -- valid
  Dendrocopos villosus septentrionalis (Nuttall, 1840) -- invalid
  Dentitheca dendritica (Nutting, 1900) -- valid
  Dicranophorus rostratus (Dixon-nuttall and Freeman, 1902) -- valid
  Dictyocladium flabellum Nutting, 1904 -- invalid
  Diphasia kincaidi (Nutting, 1901) -- invalid -- sea pine hydroid
  Diphasia pulchra Nutting, 1904 -- invalid
  Diphasia tropica Nutting, 1904 -- valid
  Elysia cornigera Nuttall, 1989 -- valid
  Eucopella sargassicola (Nutting, 1915) -- invalid
  Eudendrium album Nutting, 1896 -- valid -- white stickhydroid, white stickhydroid
  Garveia annulata Nutting, 1901 -- valid -- orange hydroid, orange hydroid
  Gonothyraea inornata Nutting, 1901 -- valid
  Grammaria immersa Nutting, 1901 -- valid
  Grammaria immersa immersa Nutting, 1901 -- valid
  Halecium corrugatum Nutting, 1899 -- valid
  Halecium ornatum Nutting, 1901 -- valid
  Halecium reversum Nutting, 1901 -- valid
  Halecium speciosum Nutting, 1901 -- valid
  Halecium washingtoni Nutting, 1901 -- valid
  Halopteris alternata (Nutting, 1900) -- valid
  Halopteris clarkei (Nutting, 1900) -- valid
  Hydrallmania distans Nutting, 1899 -- valid
  Hyperaspis elali Nutting, 1980 -- invalid
  Hyperaspis longicoxitis Nutting, 1980 -- valid
  Hyperaspis mckenziei Nutting, 1980 -- valid
  Hyperaspis querquesi Nutting, 1980 -- valid
  Lafoea adhaerens Nutting, 1901 -- valid
  Laomedea inornata (Nutting, 1901) -- valid
  Lovenella grandis Nutting, 1901 -- valid
  Macrorhynchia allmani (Nutting, 1900) -- valid
  Monotheca Nutting, 1900 -- valid
  Monotheca margaretta Nutting, 1900 -- valid
  Nemeresia pinnata (Nutting, 1900) -- invalid
  Nemertesia americana (Nutting, 1900) -- valid
  Nemertesia pinnata (Nutting, 1900) -- valid
  Nemertesia rugosa (Nutting, 1900) -- valid
  Nuditheca Nutting, 1900 -- valid
  Obelia borealis Nutting, 1901 -- invalid
  Obelia dubia Nutting, 1901 -- valid
  Opercularella hispida Nutting, 1898 -- valid
  Opercularella rugosa (Nutting, 1901) -- valid
  Orthopyxis sargassicola (Nutting, 1915) -- valid
  Parus atricapillus bartletti (Aldrich & Nutt, 1939) -- invalid
  Picoides villosus septentrionalis (Nuttall, 1840) -- valid
  Plumularia altitheca Nutting, 1900 -- valid
  Plumularia clarkei Nutting, 1900 -- valid
  Plumularia corrugata Nutting, 1900 -- invalid
  Plumularia floridana Nutting, 1900 -- valid
  Plumularia goodei Nutting, 1900 -- valid
  Plumularia inermis Nutting, 1900 -- invalid
  Plumularia margaretta (Nutting, 1900) -- invalid
  Plumularia profunda Nutting, 1900 -- valid
  Plumularia virginiae Nutting, 1900 -- valid
  Poecile atricapillus bartletti (Aldrich & Nutt, 1939) -- valid
  Psammogorgia spauldingi Nutting, 1909 -- invalid
  Selaginopsis hartlaubi (Nutting, 1904) -- valid
  Selaginopsis ornata Nutting, 1904 -- invalid
  Sertularella areyi Nutting, 1904 -- valid
  Sertularella complexa Nutting, 1904 -- valid
  Sertularella flabella (Nutting, 1904) -- valid
  Sertularella magna Nutting, 1904 -- valid
  Sertularella solitaria (Nutting, 1904) -- valid
  Sertularella tanneri Nutting, 1904 -- valid
  Sertularia dalli (Nutting, 1904) -- valid
  Sertularia mayeri Nutting, 1904 -- invalid
  Sertularia pourtalesi Nutting, 1877 -- invalid
  Sertularia stookeyi Nutting, 1904 -- invalid
  Stenostomum anops Nuttycombe and Waters, 1938 -- valid
  Stenostomum cryptops Nuttycombe and Waters, 1935 -- valid
  Stenostomum kepneri Nuttycombe and Waters, 1938 -- valid
  Stenostomum pegephilum Nuttycombe and Waters, 1938 -- valid
  Stenostomum pseudoacetabulum Nuttycombe and Waters, 1935 -- valid
  Stenostomum rhachiocaudatum Nuttycombe, 1932 -- invalid
  Stenostomum tuberculosum Nuttycombe and Waters, 1938 -- valid
  Stenostomum uronephrium Nuttycombe, 1931 -- valid
  Stenostomum ventronephrium Nuttycombe, 1932 -- valid
  Stenostomum virginianum Nuttycombe, 1931 -- valid
  Sterna forsteri Nuttall, 1834 -- valid -- Charrán de Forster, Forster's Tern, Sterne de Forster
  Swiftia kofoidi (Nutting, 1909) -- valid
  Swiftia spauldingi (Nutting, 1909) -- valid
  Symplectoscyphus elegans (Nutting, 1904) -- valid
  Symplectoscyphus levinseni (Nutting, 1904) -- valid
  Synthecium robustum Nutting, 1904 -- valid
  Thuiaria immersa Nutting, 1904 -- invalid
  Tridentata flowersi (Nutting, 1904) -- valid
  Tubularia harrimani Nutting, 1901 -- valid
  Turdus migratorius nigrideus Aldrich & Nutt, 1939 -- valid
  Vostox excavatus Nutting and Gurney, 1961 -- valid
  Zonotrichia leucophrys gambelii (Nuttall, 1840) -- valid
  Zonotrichia querula (Nuttall, 1840) -- valid -- bruant ŕ face noire, Harris' Sparrow, Harris's Sparrow
  Zygophylax cervicornis (Nutting, 1905) -- valid
 
 Kingdom Plantae
  Abies lasiocarpa (Hook.) Nutt. -- accepted -- balsam fir, Rocky Mountain fir, subalpine fir, western balsam fir, white balsam
  Abies lasiocarpa var. lasiocarpa (Hook.) Nutt. -- accepted -- subalpine fir
  Abronia fragrans Nutt. ex Hook. -- accepted -- heart's-delight, prairie snowball, snowball sand verbena, sweet sand verbena
  Abronia maritima Nutt. ex S. Watson -- accepted -- red sand verbena
  Acacia angustissima var. hirta (Nutt.) B.L. Rob. -- accepted -- prairie acacia
  Acacia hirta Nutt. -- not accepted
  Acaciella hirta (Nutt.) Britton & Rose -- not accepted
  Acer drummondii Hook. & Arn. ex Nutt. -- not accepted
  Acer glabrum var. tripartitum (Nutt. ex Torr. & A. Gray) Pax -- not accepted
  Acer grandidentatum Nutt. -- accepted -- bigtooth maple, canyon maple, sugar maple, Uvalde big-tooth maple
  Acer grandidentatum var. grandidentatum Nutt. -- accepted -- bigtooth maple, Uvalde bigtooth maple
  Acer rubrum ssp. drummondii (Hook. & Arn. ex Nutt.) E. Murray -- not accepted
  Acer rubrum var. drummondii (Hook. & Arn. ex Nutt.) Sarg. -- accepted -- Drummond's maple
  Acer saccharum ssp. grandidentatum (Nutt.) Desmarais -- not accepted
  Acer saccharum var. grandidentatum (Nutt.) Sudw. -- not accepted
  Acer tripartitum Nutt. ex Torr. & A. Gray -- not accepted
  Acerates angustifolia (Nutt.) Decne. -- not accepted
  Acerates lanuginosa (Nutt.) Decne. -- not accepted
  Acetosella paucifolia (Nutt.) Á. Löve -- not accepted
  Achillea lanulosa Nutt. -- not accepted -- western yarrow
  Achillea millefolium ssp. lanulosa (Nutt.) Piper -- not accepted
  Achillea millefolium var. lanulosa (Nutt.) Piper -- not accepted
  Acmispon americanum (Nutt.) Rydb. -- not accepted
  Acmispon americanus (Nutt.) Rydb. -- accepted -- American bird's-foot trefoil
  Acmispon americanus var. americanus (Nutt.) Rydb. -- accepted -- American bird's-foot trefoil
  Acmispon maritimus (Nutt.) D.D. Sokoloff -- accepted -- coastal bird's-foot trefoil
  Acmispon maritimus var. maritima (Nutt.) D.D. Sokoloff -- accepted -- coastal bird's-foot trefoil
  Acmispon micranthus (Nutt.) Brouillet -- accepted -- San Diego bird's-foot trefoil
  Acmispon prostratus (Nutt.) Brouillet -- accepted -- wire bird's-foot trefoil
  Acmispon strigosus (Nutt.) Brouillet -- accepted -- strigose bird's-foot trefoil
  Acnida tamariscina (Nutt.) Alph. Wood -- not accepted
  Aconitum columbianum Nutt. -- accepted -- Columbian monkshood
  Aconitum columbianum ssp. columbianum Nutt. -- accepted -- Columbian monkshood
  Aconitum columbianum var. columbianum Nutt. -- not accepted -- Columbian monkshood
  Actaea arguta Nutt. -- not accepted
  Actaea elata (Nutt.) Prantl -- accepted -- tall bugbane
  Actaea elata var. elata (Nutt.) Prantl -- accepted -- tall bugbane
  Actaea rubra ssp. arguta (Nutt.) Hultén -- not accepted -- red baneberry
  Actaea rubra var. arguta (Nutt.) G. Lawson -- not accepted
  Actaea spicata var. arguta (Nutt.) Torr. -- not accepted
  Actinella acaulis (Pursh) Nutt. -- not accepted
  Actinomeris helianthoides (Michx.) Nutt. -- not accepted
  Actinomeris nudicaulis Nutt. -- not accepted
  Actinomeris pauciflora Nutt. -- not accepted
  Aegilops hystrix Nutt. -- not accepted
  Aesculus californica (Spach) Nutt. -- accepted -- California buckeye
  Afzelia macrophylla (Nutt.) Kuntze -- not accepted
  Agalinis aphylla (Nutt.) Raf. -- accepted -- scaleleaf false foxglove
  Agalinis filifolia (Nutt.) Raf. -- accepted -- Seminole false foxglove
  Agalinis heterophylla (Nutt.) Small -- accepted -- prairie false foxglove, prairie false-foxglove
  Agalinis linifolia (Nutt.) Britton -- accepted -- flaxleaf false foxglove
  Agalinis pedicularia var. pectinata (Nutt.) S.F. Blake -- not accepted
  Agalinis tenuifolia var. parviflora (Nutt.) Pennell -- not accepted -- slender-leaf false foxglove, slenderleaf false foxglove
  Agastache anethiodora (Nutt.) Britton -- not accepted
  Agoseris elata (Nutt.) Greene -- not accepted -- tall agoseris
  Agoseris glauca var. parviflora (Nutt.) Rydb. -- not accepted
  Agoseris glauca var. pumila (Nutt.) Garrett -- not accepted
  Agoseris grandiflora (Nutt.) Greene -- accepted -- bigflower agoseris, shortbeak agoseris
  Agoseris grandiflora var. grandiflora (Nutt.) Greene -- accepted
  Agoseris heterophylla (Nutt.) Greene -- accepted -- annual agoseris, annual goatsbeard, mountain dandelion
  Agoseris heterophylla ssp. californica (Nutt.) Piper -- not accepted
  Agoseris heterophylla var. heterophylla (Nutt.) Greene -- accepted -- annual agoseris
  Agoseris laciniata (Nutt.) Greene -- not accepted
  Agoseris parviflora (Nutt.) Greene -- accepted -- false agoseris, Steppe agoseris
  Agoseris X elata (Nutt.) Greene (pro sp.) -- accepted -- tall agoseris
  Agrostis brevifolia Nutt. -- not accepted
  Agrostis oregonensis Nutt. ex A. Gray -- not accepted
  Agrostis scabrata Nutt. ex A. Gray -- not accepted
  Alcemilla occidentalis Nutt. -- not accepted
  Alchemilla cuneifolia Nutt. -- not accepted
  Alchemilla occidentalis Nutt. -- not accepted
  Aletes tenuifolius (Nutt. ex Torr. & A. Gray) W.A. Weber -- not accepted
  Aliciella pinnatifida (Nutt. ex A. Gray) J.M. Porter -- accepted -- sticky gilia
  Alisma rostrata Nutt. -- not accepted
  Alisma rostratum Nutt. -- not accepted
  Allionia decumbens (Nutt.) Spreng. -- not accepted
  Alloiatheros lepturoides (Nutt.) Steud. -- not accepted
  Allophyllum (Nutt.) A.D. Grant & V.E. Grant -- accepted -- false gilia, false gilyflower
  Allophyllum divaricatum (Nutt.) A.D. Grant & V.E. Grant -- accepted -- purple false gilyflower
  Almutaster pauciflorus (Nutt.) A. Löve & D. Löve -- accepted -- alkali marsh aster, alkali-marsh aster
  Alnus incana ssp. tenuifolia (Nutt.) Breitung -- accepted -- mountain alder, speckled alder, thinleaf alder
  Alnus maritima (Marshall) Muhl. ex Nutt. -- accepted -- seaside alder
  Alnus maritime (Marshall) Muhl. ex Nutt. -- not accepted
  Alnus oregona Nutt. -- not accepted
  Alnus rhombifolia Nutt. -- accepted -- rhombie leaf alder, white alder
  Alnus tenuifolia Nutt. -- not accepted -- mountain alder
  Amaranthus tamariscinus auct. non Nutt. -- not accepted
  Ambrosia pumila (Nutt.) A. Gray -- accepted -- dwarf bur ragweed, dwarf burr ragweed, San Diego ambrosia, San Diego ragweed
  Ambrosia tomentosa Nutt. -- accepted -- skeleton-leaf burr-ragweed, skeletonleaf bur ragweed, skeletonleaf burr ragweed, skeletonleaf bursage
  Amelanchier alnifolia (Nutt.) Nutt. ex M. Roem. -- accepted -- juneberry, Pacific serviceberry, Saskatoon serviceberry, western serviceberry, western shadbush
  Amelanchier alnifolia var. alnifolia (Nutt.) Nutt. ex M. Roem. -- accepted -- Saskatoon service-berry, Saskatoon serviceberry
  Amelanchier pumila (Torr. & A. Gray) Nutt. ex M. Roem. -- not accepted -- dwarf serviceberry
  Ammodia oregona Nutt. -- not accepted
  Amorpha californica Nutt. -- accepted -- California false indigo, mock locust
  Amorpha californica var. californica Nutt. -- accepted -- California false indigo
  Amorpha laevigata Nutt. -- accepted -- smooth false indigo, smooth indigobush
  Amorpha nana Nutt. -- accepted -- dwarf false indigo, dwarf indigo, dwarf indigobush
  Ampelamus albidus (Nutt.) Britton -- not accepted -- honeyvine milkweed
  Amphiachyris (A. DC.) Nutt. -- accepted -- amphiachyris, broomweed
  Amphiachyris dracunculoides (DC.) Nutt. -- accepted -- common broomweed, prairie broomweed
  Amphicarpa Elliott ex Nutt. -- not accepted
  Amphicarpaea Elliott ex Nutt. -- accepted -- hogpeanut
  Amphistelma scoparia (Nutt.) Small -- not accepted
  Andrachne phyllanthoides (Nutt.) Müll. Arg. -- not accepted
  Andrachne phyllanthoides (Nutt.) J.M. Coult. -- not accepted -- Missouri maidenbush
  Anemia californica Nutt. -- not accepted
  Anemone globosa (Torr. & A. Gray) Nutt. ex Pritz. -- not accepted
  Anemone heterophylla Nutt. ex Torr. & A. Gray (pro. syn.) -- not accepted
  Anemone heterophyllum Nutt. ex Torr. & A. Gray (pro. syn.) -- not accepted
  Anemone ludoviciana Nutt. -- not accepted
  Anemopsis californica (Nutt.) Hook. & Arn. -- accepted -- yerba mansa, yerba-mansa
  Anemopsis californica var. californica (Nutt.) Hook. & Arn. -- not accepted -- yerba mansa
  Angelica arguta Nutt. ex Torr. & A. Gray -- accepted -- angelica, Lyall's angelica, sharptooth angelica
  Angelica genuflexa Nutt. -- accepted -- kneeling angelica
  Anisocarpus Nutt. -- accepted
  Anisocarpus madioides Nutt. -- accepted -- woodland madia
  Anoplanthus fasciculatus (Nutt.) Walp. -- not accepted
  Antennaria dimorpha (Nutt.) Torr. & A. Gray -- accepted -- low everlasting, low pussytoes
  Antennaria labradorica Nutt. -- not accepted
  Antennaria parvifolia Nutt. -- accepted -- little-leaf pussytoes, Rocky Mountain pussytoes, small leaf pussytoes, small-leaf pussytoes, smalleaf pussytoes
  Antennaria parvifolia sensu Greene non Nutt. -- not accepted -- smallleaf pussytoes
  Anthopogon Nutt. -- not accepted
  Anthopogon brevifolius Nutt. ex Trin. -- not accepted
  Anthopogon filiformis Nutt. -- not accepted
  Anthopogon lepturoides Nutt. -- not accepted
  Anticlea elegans var. glaucus (Nutt.) Zomlefer & Judd -- accepted -- mountain deathcamas
  Aphanes occidentalis (Nutt.) Rydb. -- accepted
  Aphanisma Nutt. ex Moq. -- accepted -- coastalcreeper
  Aphanisma blitoides Nutt. ex Moq. -- accepted -- San Diego coastalcreeper
  Aphyllon fasciculatum (Nutt.) Torr. & A. Gray -- not accepted
  Apiastrum Nutt. ex Torr. & A. Gray -- accepted
  Apiastrum angustifolium Nutt. -- accepted -- mock parsley
  Apiastrum patens (Nutt. ex DC.) J.M. Coult. & Rose -- not accepted
  Apium echinatum (Nutt. ex DC.) Benth. & Hook. f. ex S. Watson -- not accepted
  Apogonia (Nutt.) E. Fourn. -- not accepted
  Apteria Nutt. -- accepted -- apteria
  Apteria aphylla (Nutt.) Barnhart ex Small -- accepted -- nodding nixie
  Arabidopsis glauca (Nutt.) Rydb. -- not accepted
  Arabis arcuata (Nutt.) A. Gray -- not accepted
  Arabis heterophylla Nutt. -- not accepted
  Arabis holboellii var. arcuata (Nutt.) Jeps. -- not accepted
  Arabis microphylla Nutt. -- not accepted -- littleleaf rockcress, small leaf rockcress
  Arabis microphylla var. microphylla Nutt. -- not accepted -- littleleaf rockcress, smallleaf rockcress
  Arabis puberula Nutt. -- not accepted -- Blue Mountain rockcress, silver rockcress
  Arabis sparsiflora Nutt. -- not accepted -- fewleaf rockcress, sicklepod rockcress
  Arabis sparsiflora var. arcuata (Nutt.) Rollins -- not accepted -- elegant rockcress
  Arabis sparsiflora var. sparsiflora Nutt. -- not accepted -- sicklepod rockcress
  Arceuthobium americanum Nutt. ex Engelm. -- accepted -- American dwarf mistletoe, lodgepole pine dwarf mistletoe
  Arctostaphylos bicolor (Nutt.) A. Gray -- not accepted
  Arctostaphylos pumila Nutt. -- accepted -- sand-mat manzanita, sandmat manzanita
  Arenaria brevifolia Nutt. ex Torr. & A. Gray -- not accepted
  Arenaria congesta Nutt. -- not accepted -- ballhead sandwort
  Arenaria congesta var. congesta Nutt. -- not accepted -- ballhead sandwort
  Arenaria hookeri Nutt. -- not accepted -- Hooker's sandwort
  Arenaria hookeri ssp. hookeri Nutt. -- not accepted -- Hooker's sandwort
  Arenaria hookeri var. hookeri Nutt. -- not accepted
  Arenaria pungens Nutt. -- not accepted
  Arenaria tenella Nutt. -- not accepted
  Argemone glauca (Nutt. ex Prain) Pope -- accepted -- smooth pricklypoppy
  Argemone glauca var. glauca (Nutt. ex Prain) Pope -- accepted -- smooth pricklypoppy
  Argythammia mercurialina (Nutt.) Müll. Arg. -- not accepted
  Argythamnia mercurialina (Nutt.) Müll. Arg. -- not accepted -- tall silverbush, tall wildmercury
  Argythamnia mercurialina var. mercurialina (Nutt.) Müll. Arg. -- not accepted -- tall silverbush, tall wildmercury
  Arisaema quinatum (Nutt.) Schott -- not accepted
  Arisaema triphyllum ssp. quinatum (Nutt.) Huttl. -- not accepted -- Jack in the pulpit
  Aristida pallens Nutt. -- not accepted
  Aristida purpurea Nutt. -- accepted -- purple 3-awn, purple three-awn, purple threeawn, red threeawn
  Aristida purpurea var. purpurea Nutt. -- accepted -- purple threeawn
  Aristida tuberculosa Nutt. -- accepted -- seaside threeawn
  Aristolochia hastata Nutt. -- not accepted
  Aristolochia reticulata Nutt. -- accepted -- Texas dutchman's pipe
  Aristolochia serpentaria var. hastata (Nutt.) Duch. -- not accepted
  Arnica amplexicaulis Nutt. -- not accepted -- clasping arnica, streambank arnica
  Arnica chamissonis ssp. foliosa (Nutt.) Maguire -- not accepted -- arnica de Chamisso sous-espčce multifeuille, Chamisso arnica
  Arnica chamissonis ssp. foliosa var. andina (Nutt.) Ediger & T.M. Barkley -- not accepted -- Chamisso arnica
  Arnica chamissonis var. andina (Nutt.) Ediger & T.M. Barkl. -- not accepted -- Chamisso arnica
  Arnica chamissonis var. foliosa (Nutt.) Maguire -- not accepted
  Arnica foliosa Nutt. -- not accepted
  Arnica lanceolata Nutt. -- accepted -- arnica, arnica ŕ aigrettes brunes, lanceleaf arnica
  Arnica lanceolata ssp. lanceolata Nutt. -- accepted -- arnica ŕ aigrettes brunes, lanceleaf arnica
  Aronia alnifolia Nutt. -- not accepted
  Artemisia arbuscula Nutt. -- accepted -- little sagebrush, low sagebrush
  Artemisia arbuscula ssp. arbuscula Nutt. -- accepted -- gray low sagebrush, little sagebrush
  Artemisia campestris ssp. pacifica (Nutt.) H.M. Hall & Clem. -- accepted -- field sagewort, Pacific wormwood, western sagewort
  Artemisia campestris var. pacifica (Nutt.) M. Peck -- not accepted
  Artemisia gnaphalodes Nutt. -- not accepted
  Artemisia incompta Nutt. -- not accepted
  Artemisia longifolia Nutt. -- accepted -- longleaf sagebrush, longleaf wormwood
  Artemisia ludoviciana Nutt. -- accepted -- cudweed sagewort, gray sagewort, Louisiana sagewort, Louisiana wormwood, mugwort wormwood, prairie sage, white sagebrush
  Artemisia ludoviciana ssp. incompta (Nutt.) D.D. Keck -- accepted -- Columbia River wormwood, mountain sagewort, white sagebrush
  Artemisia ludoviciana ssp. ludoviciana Nutt. -- accepted -- cudweed sagewort, foothill sagewort, Louisiana sagewort, white sagebrush
  Artemisia ludoviciana var. gnaphalodes (Nutt.) Torr. & A. Gray -- not accepted
  Artemisia ludoviciana var. incompta (Nutt.) Cronquist -- not accepted
  Artemisia ludoviciana var. latiloba Nutt. -- not accepted
  Artemisia pacifica Nutt. -- not accepted
  Artemisia pedatifida Nutt. -- accepted -- birdfoot sagebrush
  Artemisia rigida (Nutt.) A. Gray -- accepted -- scabland sagebrush
  Artemisia serrata Nutt. -- accepted -- sawtooth wormwood
  Artemisia tridentata Nutt. -- accepted -- big sagebrush, big sagebush
  Artemisia tridentata ssp. arbuscula (Nutt.) H.M. Hall & Clem. -- not accepted
  Artemisia tridentata ssp. tridentata Nutt. -- accepted -- basin big sagebrush, big sagebrush
  Artemisia tridentata ssp. trifida (Nutt.) H.M. Hall & Clem. -- not accepted
  Artemisia trifida Nutt. -- not accepted
  Artemisia trifida var. rigida Nutt. -- not accepted
  Artemisia vulgaris ssp. heterophylla (Nutt.) H.M. Hall & Clem. -- not accepted
  Artemisia vulgaris ssp. ludoviciana (Nutt.) H.M. Hall & Clem. -- not accepted
  Artemisia vulgaris var. ludoviciana (Nutt.) Kuntze -- not accepted
  Arundinaria tecta var. pumila (Nutt.) Rupr. -- not accepted
  Arundo canadensis Nutt. ex Steud. -- not accepted
  Asclepias asperula var. decumbens (Nutt.) Shinners -- not accepted
  Asclepias decumbens (Nutt.) K. Schum. -- not accepted
  Asclepias lanuginosa Nutt. -- accepted -- side-cluster milkweed, sidecluster milkweed, small-green milkweed, woolly milkweed
  Asclepiodora decumbens (Nutt.) A. Gray -- not accepted
  Asperella angustifolia Nutt. -- not accepted
  Aspidotis (Nutt. ex Hook.) Copel. -- accepted -- lacefern
  Aspidotis californica (Hook.) Nutt. ex Copel. -- accepted -- California lacefern
  Asplenium pinnatifidum Nutt. -- accepted -- lobed spleenwort
  Asprella americana Nutt. -- not accepted
  Aster adnatus Nutt. -- not accepted -- scaleleaf aster
  Aster amethystinus Nutt. -- not accepted
  Aster bracteolatus auct. non Nutt. -- not accepted -- bract aster
  Aster campestris Nutt. -- not accepted -- meadow aster
  Aster campestris var. campestris Nutt. -- not accepted -- western meadow aster
  Aster canescens var. viscosus (Nutt.) A. Gray -- not accepted
  Aster divaricatus (Nutt.) Torr. & A. Gray non L. -- not accepted -- aster ŕ rameaux étalés, serpentine aster, white wood aster
  Aster elegans (Nutt.) Torr. & A. Gray non Willd. -- not accepted
  Aster frondosus (Nutt.) Torr. & A. Gray -- not accepted
  Aster glabriuscula (Nutt.) Torr. & A. Gray -- not accepted
  Aster glacialis Nutt. -- not accepted
  Aster gracilis Nutt. -- not accepted -- slender aster
  Aster integrifolius Nutt. -- not accepted -- thickstem aster
  Aster oblongifolius Nutt. -- not accepted -- aromatic aster
  Aster occidentalis (Nutt.) Torr. & A. Gray -- not accepted -- western aster
  Aster occidentalis var. occidentalis (Nutt.) Torr. & Gray -- not accepted -- western aster
  Aster oregonensis (Nutt.) Cronquist -- not accepted
  Aster oregonensis ssp. oregonensis (Nutt.) Cronq. -- not accepted -- Oregon aster
  Aster oregonum (Nutt.) Torr. & A. Gray -- not accepted
  Aster oregonus auct. non (Nutt.) Torr. & A. Gray -- not accepted
  Aster pauciflorus Nutt. -- not accepted
  Aster X amethystinus Nutt. (pro sp.) -- not accepted -- amethyst aster
  Aster xylorhiza (Nutt.) Torr. & A. Gray -- not accepted
  Astragalus argophyllus Nutt. -- accepted -- silver-leaf milkvetch, silverleaf milkvetch
  Astragalus argophyllus var. argophyllus Nutt. -- accepted -- silverleaf milkvetch
  Astragalus caespitosus (Nutt.) A. Gray -- not accepted
  Astragalus canadensis var. mortonii (Nutt.) S. Watson -- accepted -- Morton's Canadian milkvetch
  Astragalus catalinensis Nutt. -- not accepted
  Astragalus crassicarpus Nutt. -- accepted -- ground-plum, groundplum milkvetch
  Astragalus crassicarpus var. crassicarpus Nutt. -- accepted -- ground-plum, groundplum milkvetch
  Astragalus crassicarpus var. trichocalyx (Nutt. ex Torr. & A. Gray) Barneby ex Gleason -- accepted -- groundplum milkvetch, Ozark groundplum
  Astragalus decumbens (Nutt. ex Torr. & A. Gray) A. Gray -- not accepted
  Astragalus diversifolius var. campestris (Nutt.) Dorn -- not accepted
  Astragalus flavus Nutt. ex Torr. & A. Gray -- accepted -- yellow milkvetch
  Astragalus flavus var. flavus Nutt. -- accepted -- yellow milkvetch
  Astragalus goniatus Nutt. ex Torr. & A. Gray -- not accepted
  Astragalus gracilis Nutt. -- accepted -- milkvetch, slender milkvetch
  Astragalus megacarpus (Nutt.) A. Gray -- accepted -- bladdery milkvetch, great bladdery milkvetch
  Astragalus mexicanus var. trichocalyx (Nutt. ex Torr. & A. Gray) Fernald -- not accepted
  Astragalus miser var. decumbens (Nutt. ex Torr. & A. Gray) Cronquist -- accepted -- prostrate milkvetch
  Astragalus miser var. tenuifolius (Nutt.) Barneby -- accepted -- timber milkvetch
  Astragalus missouriensis Nutt. -- accepted -- Missouri milk-vetch, Missouri milkvetch
  Astragalus missouriensis var. missouriensis Nutt. -- accepted -- Missouri milk-vetch, Missouri milkvetch
  Astragalus mortonii Nutt. -- not accepted
  Astragalus oreganus Nutt. -- accepted -- Oregon milkvetch
  Astragalus plattensis Nutt. -- accepted -- Platte milkvetch, Platte River milk-vetch, Platte River milkvetch
  Astragalus shortianus Nutt. -- accepted -- Short's milkvetch
  Astragalus simplicifolius (Nutt.) A. Gray -- accepted -- little bun milkvetch
  Astragalus striatus Nutt. -- not accepted
  Astragalus trichocalyx Nutt. ex Torr. & A. Gray -- not accepted
  Astragalus trichopodus (Nutt.) A. Gray -- accepted -- Santa Barbara milkvetch
  Astragalus trichopodus var. trichopodus (Nutt.) A. Gray -- accepted -- Santa Barbara milkvetch
  Astragalus viridis (Nutt. ex Torr. & A. Gray) E. Sheld. -- not accepted
  Astranthium Nutt. -- accepted -- western daisy
  Astranthium integrifolium (Michx.) Nutt. -- accepted -- entireleaf western daisy
  Astranthium integrifolium ssp. integrifolium (Michx.) Nutt. -- accepted -- entireleaf western daisy
  Astranthuim Nutt. -- not accepted
  Astranthuim integrifolium (Michx.) Nutt. -- not accepted
  Astranthuim integrifolium var. integrifolium (Michx.) Nutt. -- not accepted
  Atheropogon oligostachyus Nutt. -- not accepted
  Atragene columbiana Nutt. -- not accepted
  Atriplex arenaria Nutt. -- not accepted
  Atriplex argentea Nutt. -- accepted -- silverscale, silverscale saltbush, silverscale saltweed
  Atriplex argentea ssp. argentea Nutt. -- not accepted -- silverscale, silverscale saltbush
  Atriplex argentea ssp. argentea var. argentea Nutt. -- not accepted -- silverscale, silverscale saltbush
  Atriplex argentea var. argentea Nutt. -- accepted -- silverscale saltbush
  Atriplex canescens (Pursh) Nutt. -- accepted -- fourwing saltbush
  Atriplex canescens ssp. canescens (Pursh) Nutt. -- not accepted -- fourwing saltbush, shad-scale saltbush
  Atriplex canescens var. canescens (Pursh) Nutt. -- accepted -- fourwing saltbush
  Atriplex dioica (Nutt.) J.F. Macbr. -- not accepted
  Atriplex patula ssp. subspicata (Nutt.) Fosberg -- not accepted
  Atriplex patula var. subspicata (Nutt.) S. Watson -- not accepted
  Atriplex subspicata (Nutt.) Rydb. -- not accepted -- halberdleaf orach, orach saltbush, saline saltbush, spearscale, spreading orach
  Atropis airoides (Nutt.) Holmb. -- not accepted
  Aulaxia Nutt. -- not accepted
  Aulaxia ciliata (Elliott) Nutt. -- not accepted
  Aulaxia rufa (Elliott) Nutt. -- not accepted
  Aureolaria pectinata (Nutt.) Pennell -- accepted -- combleaf yellow false foxglove
  Aureolaria pedicularia var. pectinata (Nutt.) Gleason -- not accepted
  Baeria uliginosa (Nutt.) A. Gray -- not accepted
  Bahia oppositifolia (Nutt.) A. Gray -- not accepted
  Balduina Nutt. -- accepted -- honeycombhead
  Balduina uniflora Nutt. -- accepted -- oneflower honeycombhead
  Balsamorhiza Nutt. -- accepted -- balsamroot
  Balsamorhiza deltoidea Nutt. -- accepted -- deltoid balsamroot
  Balsamorhiza hirsuta Nutt. -- not accepted
  Balsamorhiza hookeri (Hook.) Nutt. -- accepted -- hairy balsamroot, Hooker's balsamroot, neglected balsamroot, rabbithead balsamroot
  Balsamorhiza hookeri var. hirsuta (Nutt.) A. Nelson -- not accepted -- hairy balsamroot
  Balsamorhiza hookeri var. hookeri (Hook.) Nutt. -- not accepted -- Hooker's balsamroot
  Balsamorhiza incana Nutt. -- accepted -- hoary balsamroot
  Balsamorhiza macrophylla Nutt. -- accepted -- cutleaf balsamroot, Idaho balsamroot
  Balsamorhiza sagittata (Pursh) Nutt. -- accepted -- arrowleaf balsamroot
  Balsamorhiza X terebinthacea (Hook.) Nutt. (pro sp.) -- accepted -- balsamroot
  Baptisia bracteata var. leucophaea (Nutt.) Kartesz & Gandhi -- not accepted -- longbract wild indigo
  Baptisia leucophaea Nutt. -- accepted -- longbract wild indigo
  Baptisia sphaerocarpa Nutt. -- accepted -- green wild indigo, round wild indigo, yellow wild indigo
  Baptisia villosa auct. non (Walter) Nutt. -- not accepted
  Baptisia X microphylla Nutt. (pro. sp.) -- accepted -- small leaf wild indigo
  Batodendron arboreum (Marsh) Nutt. -- not accepted
  Berlandiera pumila (Michx.) Nutt. -- accepted -- soft greeneyes
  Berlandiera pumila var. pumila (Michx.) Nutt. -- not accepted
  Berlandiera subacaulis (Nutt.) Nutt. -- accepted -- Florida greeneyes
  Berlandiera tomentosa (Pursh) Nutt. -- not accepted
  Berthelotia sericea (Nutt.) Rydb. -- not accepted
  Bidens bidentoides (Nutt.) Britton -- accepted -- Delmarva beggarticks
  Bidens cernua var. dentata (Nutt.) B. Boivin -- not accepted
  Bidens connata var. petiolata (Nutt.) Farw. -- not accepted
  Bidens gracilis Nutt. -- not accepted
  Bidens involucrata (Nutt.) Britton -- not accepted
  Bidens mitis var. leptophylla (Nutt.) Small -- not accepted
  Bigelowia virgata (Nutt.) DC. -- not accepted
  Blephariglotis leucophaea (Nutt.) Farw. -- not accepted
  Blephariglottis leucophaea (Nutt.) Farw. -- not accepted
  Boechera angustifolia (Nutt.) Dorn -- not accepted
  Boechera arcuata (Nutt.) Windham & Al-Shehbaz -- accepted -- elegant rockcress
  Boechera microphylla (Nutt.) Dorn -- accepted -- littleleaf rockcress
  Boechera microphylla var. microphylla (Nutt.) Dorn -- not accepted
  Boechera pauciflora (Nutt.) Windham & Al-Shehbaz -- accepted -- hairystem rockcress
  Boechera puberula (Nutt.) Dorn -- accepted -- silver rockcress
  Boechera sparsiflora (Nutt.) Dorn -- accepted -- sicklepod rockcress
  Boisduvalia densiflora var. salicina (Nutt. ex Torr. & A. Gray) Munz -- not accepted
  Boisduvalia glabella (Nutt.) Walp. -- not accepted
  Boisduvalia salicina (Nutt. ex Torr. & A. Gray) Rydb. -- not accepted
  Bolophyta alpina Nutt. -- not accepted
  Borya distichophylla Nutt. -- not accepted
  Bouteloua dactyloides (Nutt.) Columbus -- accepted
  Bouteloua oligostachya (Nutt.) Torr. ex A. Gray -- not accepted
  Boykinia Nutt. -- accepted -- brookfoam
  Boykinia aconitifolia Nutt. -- accepted -- Allegheny brookfoam, brook saxifrage
  Boykinia elata (Nutt.) Greene -- not accepted
  Brachyactis frondosa (Nutt.) A. Gray -- not accepted -- leafy rayless aster
  Bradburia pilosa (Nutt.) Semple -- accepted -- soft goldenaster
  Brauneria pallida (Nutt.) Britton -- not accepted
  Breitungia oregana (Nutt.) Á. Löve & D. Löve -- not accepted
  Brickellia grandiflora (Hook.) Nutt. -- accepted -- mountain brickellbush, tasselflower brickellbush, tasselflower brickellia
  Brickellia microphylla (Nutt.) A. Gray -- accepted -- littleleaf brickellbush
  Brickellia microphylla var. microphylla (Nutt.) A. Gray -- accepted -- littleleaf brickellbush, Watson's brickellbush
  Brickellia oblongifolia Nutt. -- accepted -- Mohave brickellbush, Mojave brickellbush, narrowleaf brickellbush
  Brickellia oblongifolia var. oblongifolia Nutt. -- accepted -- Mojave brickellbush, narrowleaf brickellbush
  Briza canadensis Nutt. -- not accepted
  Bromus californicus Nutt. ex Buckley -- not accepted
  Bromus debilis Nutt. ex Shear -- not accepted
  Bromus muticus Nutt. ex A. Gray -- not accepted
  Bromus nitens Nutt. ex A. Gray -- not accepted
  Bromus oregonus Nutt. ex Hook. f. -- not accepted
  Bromus oregonus Nutt. ex Shear -- not accepted
  Bromus parviflorus Nutt. ex A. Gray -- not accepted
  Bromus pauciflorus Nutt. ex Shear -- not accepted
  Bruchmannia Nutt. -- not accepted
  Buchloe dactyloides (Nutt.) Engelm. -- not accepted -- buffalograss
  Buckleya distichophylla (Nutt.) Torr. -- accepted -- piratebush
  Bulbilis dactyloides (Nutt.) Raf. ex Kuntze -- not accepted
  Bulbostylis annua Nutt. -- not accepted
  Bumelia angustifolia Nutt. -- not accepted
  Bumelia celastrina var. angustifolia (Nutt.) R.W. Long -- not accepted
  Bumelia lanuginosa ssp. oblongifolia (Nutt.) Cronquist -- not accepted
  Bumelia lanuginosa var. oblongifolia (Nutt.) R.B. Clark -- not accepted
  Bumelia macrocarpa Nutt. -- not accepted
  Bumelia oblongifolia Nutt. -- not accepted
  Cacalia lanceolata Nutt. -- not accepted
  Cacalia tuberosa Nutt. -- not accepted
  Cactus fragilis Nutt. -- not accepted
  Cactus viviparus Nutt. -- not accepted
  Cakile americana Nutt. -- not accepted
  Calamagrostis andina Nutt. -- not accepted
  Calamagrostis columbiensis Nutt. ex A. Gray -- not accepted
  Calamagrostis gigantea Nutt. -- not accepted
  Calamagrostis mexicana Nutt. -- not accepted
  Calamagrostis pallida Nutt. ex A. Gray -- not accepted
  Calamintha arkansana (Nutt.) Shinners -- not accepted -- limestone calamint
  Calamintha coccinea (Nutt. ex Hook.) Benth. -- not accepted -- scarlet calamint
  Calamovilfa gigantea (Nutt.) Scribn. & Merr. -- accepted -- big sandreed, giant sandreed
  Calandrinia maritima Nutt. -- not accepted
  Calanthera dactyloides (Nutt.) Kunth ex Hook. -- not accepted
  Callirhoe Nutt. -- accepted -- polly mallow, poppymallow
  Callirhoe digitata Nutt. -- accepted -- fringe poppymallow, winecup
  Callirhoe pedata auct. non (Nutt. ex Hook.) Gray -- not accepted -- palmleaf poppymallow
  Callirhoe pedata (Nutt. ex Hook.) A. Gray -- accepted -- palmleaf poppymallow
  Callitriche pedunculosa Nutt. -- accepted -- Nuttall's water-starwort
  Callitriche peploides Nutt. -- accepted -- matted water-starwort, matted waterstarwort
  Callitriche peploides var. peploides Nutt. -- accepted
  Calycadenia tenella (Nutt.) Torr. & A. Gray -- not accepted
  Calycanthus floridus var. oblongifolius (Nutt.) Boufford & Spongberg -- not accepted
  Calycocarpum (Nutt.) Spach -- accepted
  Calycodon Nutt. -- not accepted
  Calycodon montanus Nutt. -- not accepted
  Calylophus serrulatus (Nutt.) P.H. Raven -- not accepted -- halfshrub calylophus, halfshrub sundrop, serrateleaf eveningprimrose, yellow sundrops
  Calylophus serrulatus var. spinulosus (Nutt. ex Torr. & A. Gray) Shinners -- not accepted
  Calymenia decumbens Nutt. -- not accepted
  Calyptridium Nutt. -- not accepted
  Calyptridium monandrum Nutt. -- not accepted
  Calytophus serrulatus (Nutt.) P.H. Raven -- not accepted
  Camissonia andina (Nutt.) P.H. Raven -- not accepted -- Blackfoot River evening primrose, Blackfoot River evening-primrose, plateau primrose
  Camissonia bistorta (Nutt. ex Torr. & A. Gray) P.H. Raven -- not accepted -- southern suncup
  Camissonia californica (Nutt. ex Torr. & A. Gray) P.H. Raven -- not accepted -- California primrose, California suncup
  Camissonia ovata (Nutt. ex Torr. & A. Gray) P.H. Raven -- not accepted -- goldeneggs
  Camissonia parvula (Nutt. ex Torr. & A. Gray) P.H. Raven -- accepted -- Lewis River suncup
  Camissoniopsis bistorta (Nutt. ex Torr. & A. Gray) W.L. Wagner & Hoch -- accepted -- southern suncup
  Cardamine californica (Nutt.) Greene -- accepted -- milkmaids
  Cardamine californica var. californica (Nutt.) Greene -- not accepted -- milkmaids
  Cardamine californica var. integrifolia (Nutt.) Rollins -- not accepted -- milkmaids
  Cardamine heterophylla (Nutt.) Alph. Wood -- not accepted
  Cardamine integrifolia (Nutt.) Greene -- not accepted
  Cardamine maxima (Nutt.) Alph. Wood -- accepted -- large toothwort
  Cardamine oligosperma Nutt. -- accepted -- Idaho bittercress, little western bittercress
  Cardamine oligosperma var. oligosperma Nutt. -- not accepted -- little western bittercress
  Carduus discolor (Muhl. ex Willd.) Nutt. -- not accepted
  Carduus pumilus Nutt. -- not accepted
  Carduus undulatus Nutt. -- not accepted
  Carduus undulatus var. canescens (Nutt.) Porter -- not accepted
  Carex aurea Nutt. -- accepted -- golden sedge, golden-fruit sedge
  Carex collinsii Nutt. -- accepted -- Collins' sedge
  Carex filifolia Nutt. -- accepted -- threadleaf sedge
  Carex filifolia var. filifolia Nutt. -- accepted -- sedge
  Carex squarrosa var. typhina (Michx.) Nutt. -- not accepted
  Carphephorus corymbosus (Nutt.) Torr. & A. Gray -- accepted -- coastal plain chaffhead, coastalplain chaffhead
  Carya Nutt. -- accepted -- caryer, hickory
  Carya alba (L.) Nutt. -- not accepted -- mockernut hickory
  Carya aquatica Nutt. -- not accepted -- bitter pecan, water hickory
  Carya microcarpa (Nutt.) Britton -- not accepted
  Carya oliviformis (Michx. f.) Nutt. -- not accepted
  Carya tomentosa (Lam. ex Poir.) Nutt. -- accepted -- mockernut hickory
  Casiostega dactyloides (Nutt.) E. Fourn. -- not accepted
  Castanea alnifolia Nutt. -- not accepted -- Florida chinkapin
  Castilleja angustifolia (Nutt.) G. Don -- accepted -- northwestern Indian paintbrush, northwestern paintbrush
  Castilleja angustifolia var. angustifolia (Nutt.) G. Don -- accepted -- northwestern Indian paintbrush
  Castilleja angustifolia var. bradburii (Nutt.) Fernald -- not accepted
  Castilleja purpurea (Nutt.) G. Don -- accepted -- downy Indian paintbrush, Indian paintbrush
  Castilleja purpurea var. purpurea (Nutt.) G. Don -- accepted -- downy Indian paintbrush
  Caulanthus heterophyllus (Nutt.) Payson -- accepted -- San Diego wild cabbage
  Caulanthus heterophyllus var. heterophyllus (Nutt.) Payson -- not accepted -- San Diego wild cabbage
  Ceanothus cuneatus (Hook.) Nutt. -- accepted -- buckbrush
  Ceanothus cuneatus ssp. cuneatus (Hook.) Nutt. -- not accepted -- coast buckbrush
  Ceanothus cuneatus ssp. rigidus (Nutt.) C.L. Schmidt -- not accepted -- Monterey ceanothus
  Ceanothus cuneatus var. cuneatus (Hook.) Nutt. -- accepted -- buckbrush
  Ceanothus cuneatus var. rigidus (Nutt.) Hoover -- accepted -- Monterey ceanothus
  Ceanothus divaricatus Nutt. -- not accepted
  Ceanothus hirsutus Nutt. -- not accepted
  Ceanothus megacarpus Nutt. -- accepted -- bigpod ceanothus
  Ceanothus megacarpus ssp. megacarpus Nutt. -- not accepted -- bigpod ceanothus
  Ceanothus megacarpus var. megacarpus Nutt. -- accepted -- bigpod ceanothus
  Ceanothus oliganthus Nutt. -- accepted -- hairy ceanothus
  Ceanothus oliganthus ssp. oliganthus Nutt. -- not accepted -- explorer's bush
  Ceanothus oliganthus var. oliganthus Nutt. -- not accepted -- California-lilac
  Ceanothus oreganus Nutt. -- not accepted
  Ceanothus rigidus Nutt. -- not accepted
  Ceanothus serpyllifolius Nutt. -- accepted -- coastal plain buckbrush
  Ceanothus spinosus Nutt. -- accepted -- greenbark ceanothus, redheart
  Ceanothus verrucosus Nutt. -- accepted -- barranca brush, wart-stemmed ceanothus
  Celtis tenuifolia Nutt. -- accepted -- dwarf hackberry, Georgia hackberry
  Centaurea americana Nutt. -- not accepted -- American basketflower, American star thistle, American star-thistle
  Cerasus demissa Nutt. -- not accepted
  Cerasus ilicifolia Nutt. ex Hook. & Arn. -- not accepted
  Cercocarpus betuloides Nutt. -- accepted -- birch-leaf mountain-mahogany
  Cercocarpus betuloides var. betuloides Nutt. -- accepted -- birch-leaf mountain-mahogany
  Cercocarpus ledifolius Nutt. -- accepted -- curl-leaf mountain-mahogany, curlleaf cercocarpus
  Cercocarpus ledifolius var. ledifolius Nutt. -- accepted -- curl-leaf mountain-mahogany
  Cercocarpus parvifolius Nutt. ex Hook. & Arn. -- not accepted
  Chaenactis glabriuscula var. denudata (Nutt.) Munz -- not accepted
  Chaenactis glabriuscula var. tenuifolia (Nutt.) H.M. Hall -- not accepted
  Chaenactis tenuifolia Nutt. -- not accepted
  Chaerophyllum dasycarpum (Hook. ex S. Watson) Nutt. ex Small -- not accepted
  Chaetaria tuberculosa (Nutt.) Schult. -- not accepted
  Chaetopappa asteroides Nutt. ex DC. -- accepted -- Arkansas leastdaisy, least daisy
  Chaetopappa asteroides var. asteroides Nutt. ex DC. -- accepted -- Arkansas leastdaisy
  Chaetopappa aurea (Nutt.) D.D. Keck -- not accepted
  Chamaeraphis glauca var. laevigata (Nutt.) Beal -- not accepted
  Chamaerhodos erecta var. parviflora (Nutt.) C.L. Hitchc. -- not accepted
  Cheirinia aspera (Nutt.) Britton -- not accepted
  Cheirodendron Nutt. ex Seem. -- accepted
  Chenopodium leptophyllum (Moq.) Nutt. ex S. Watson -- accepted -- narrowleaf goosefoot, narrowleaf lambsquarters, narrowleaved goosefoot, slimleaf goosefoot, slimleaf lambsquarters
  Chloris verticillata Nutt. -- accepted -- tumble windmill grass, Tumble Windmillgrass, windmillgrass
  Chloropyron maritimum (Nutt. ex Benth.) A. Heller -- accepted -- saltmarsh bird's-beak
  Chloropyron maritimum ssp. maritimus Nutt. ex Benth. -- accepted -- saltmarsh bird's-beak
  Chondrophora virgata (Nutt.) Greene -- not accepted
  Chondrosum oligostachyum (Nutt.) Torr. -- not accepted
  Chorizanthe angustifolia Nutt. -- accepted -- narrowleaf spineflower
  Chorizanthe discolor Nutt. -- not accepted
  Chorizanthe fimbriata Nutt. -- accepted -- fringed spineflower
  Chorizanthe fimbriata var. fimbriata Nutt. -- accepted -- fringed spineflower
  Chorizanthe procumbens Nutt. -- accepted -- prostrate spineflower
  Chorizanthe uncinata Nutt. -- not accepted
  Chretomeris Nutt. ex J.G. Sm. -- not accepted
  Chretomeris trichoides Nutt. ex J.G. Sm. -- not accepted
  Chrysanthemum bipinnatum ssp. huronense (Nutt.) Hultén -- not accepted
  Chrysoma Nutt. -- accepted -- chrysoma
  Chrysoma solidaginoides Nutt. -- not accepted
  Chrysopsis (Nutt.) Elliot -- accepted -- goldenaster
  Chrysopsis alpina Nutt. -- not accepted
  Chrysopsis foliosa Nutt. -- not accepted
  Chrysopsis gossypina ssp. hyssopifolia (Nutt.) Semple -- accepted -- cottony goldenaster
  Chrysopsis hyssopifolia Nutt. -- not accepted
  Chrysopsis mollis Nutt. -- not accepted
  Chrysopsis oregona (Nutt.) A. Gray -- not accepted
  Chrysopsis pilosa (Walter) Britton non Nutt. -- not accepted -- soft goldenaster
  Chrysopsis pilosa Nutt. -- not accepted -- soft goldaster, soft goldenaster
  Chrysopsis sessiliflora Nutt. -- not accepted
  Chrysopsis trichophylla (Nutt.) Elliot -- not accepted
  Chrysopsis villosa (Pursh) Nutt. ex DC. -- not accepted
  Chrysopsis villosa var. foliosa (Nutt.) D.C. Eaton -- not accepted
  Chrysopsis villosa var. sessiliflora (Nutt.) A. Gray -- not accepted
  Chrysosplenium glechomifolium Nutt. -- accepted -- Pacific golden saxifrage
  Chrysothamnus Nutt. -- accepted -- rabbitbrush
  Chrysothamnus depressus Nutt. -- accepted -- dwarf rabbitbrush, longflower rabbitbrush
  Chrysothamnus graveolens (Nutt.) Greene -- not accepted
  Chrysothamnus nauseosus ssp. albicaulis (Nutt.) H.M. Hall & Clem. -- not accepted
  Chrysothamnus nauseosus ssp. graveolens (Nutt.) Piper -- not accepted
  Chrysothamnus nauseosus ssp. speciosus (Nutt.) H.M. Hall & Clem. -- not accepted
  Chrysothamnus nauseosus var. albicaulis (Nutt.) Rydb. -- not accepted
  Chrysothamnus nauseosus var. graveolens (Nutt.) Piper ex H.M. Hall -- not accepted
  Chrysothamnus nauseosus var. speciosus (Nutt.) H.M. Hall -- not accepted
  Chrysothamnus viscidiflorus (Hook.) Nutt. -- accepted -- Douglas rabbitbrush, Douglas' rabbitbrush, green rabbitbrush, yellow rabbitbrush
  Chrysothamnus viscidiflorus ssp. lanceolatus (Nutt.) H.M. Hall & Clem. -- accepted -- lanceleaf low rabbitbrush, lanceleaf rabbitbrush, yellow rabbitbrush
  Chrysothamnus viscidiflorus ssp. pumilus (Nutt.) H.M. Hall & Clem. -- not accepted
  Chrysothamnus viscidiflorus ssp. viscidiflorus (Hook.) Nutt. -- accepted -- Douglas' rabbitbrush, green rabbitbrush, yellow rabbitbrush
  Chrysothamnus viscidiflorus ssp. viscidiflorus var. viscidiflorus (Hook.) Nutt. -- not accepted -- Douglas' rabbitbrush, green rabbitbrush, yellow rabbitbrush
  Chrysothamnus viscidiflorus var. lanceolatus (Nutt.) Greene -- not accepted
  Chrysothamnus viscidiflorus var. pumilus (Nutt.) Jeps. -- not accepted
  Chrysothamnus viscidiflorus var. viscidiflorus (Hook.) Nutt. -- not accepted -- yellow rabbitbrush
  Chylismia (Nutt. ex Torr. & A. Gray) Raim. -- accepted
  Chylismia scapoidea (Torr. & A. Gray) Nutt. ex Raim. -- accepted
  Chylismia scapoidea ssp. scapoidea (Torr. & A. Gray) Nutt. ex Raim. -- accepted
  Cimicifuga elata Nutt. -- not accepted -- tall bugbane
  Cimicifuga racemosa (L.) Nutt. -- not accepted -- black bugbane, black cohosh, black snakeroot
  Cinna arkansana (Nutt.) G.C. Tucker -- not accepted
  Cirsium brevifolium Nutt. -- accepted -- Palouse thistle
  Cirsium canescens Nutt. -- accepted -- Platte thistle, prairie thistle
  Cirsium edule Nutt. -- accepted -- cardoon, edible thistle, Hall's thistle
  Cirsium edule var. edule Nutt. -- accepted -- edible thistle, Hall's thistle
  Cirsium hookerianum Nutt. -- accepted -- white thistle
  Cirsium horridulum var. megacanthum (Nutt.) D.J. Keil -- accepted
  Cirsium occidentale (Nutt.) Jeps. -- accepted -- cobwebby thistle
  Cirsium occidentale var. occidentale (Nutt.) Jeps. -- accepted -- cobwebby thistle
  Cirsium scariosum Nutt. -- accepted -- meadow thistle
  Cirsium scariosum var. scariosum Nutt. -- accepted -- meadow thistle
  Cirsium stenolepidum Nutt. -- not accepted
  Cirsium undulatum (Nutt.) Spreng. -- accepted -- gray thistle, wavy-leaf thistle, wavyleaf thistle
  Cirsium undulatum var. undulatum (Nutt.) Spreng. -- accepted -- gray thistle, wavy-leaf thistle, wavyleaf thistle
  Cissampelos pauciflora Nutt. -- not accepted
  Cistanthe maritima (Nutt.) Hershk. -- accepted -- seaside pussypaws
  Cistanthe monandra (Nutt.) Hershk. -- accepted -- common pussypaws, sandcress
  Cladothrix lanuginosa Nutt. -- not accepted
  Clarkia epilobioides (Nutt. ex Torr. & A. Gray) A. Nelson & J.F. Macbr. -- accepted -- canyon clarkia, canyon fairyfan
  Claytonia dichotoma Nutt. -- not accepted
  Claytonia diffusa Nutt. -- not accepted
  Claytonia parviflora var. glauca Nutt. ex Torr. & A. Gray -- not accepted
  Clematis columbiana (Nutt.) Torr. & A. Gray -- accepted -- Columbian virgin's-bower, rock clematis
  Clematis columbiana var. columbiana (Nutt.) Torr. & A. Gray -- accepted -- Columbian virginsbower, rock clematis
  Clematis lasiantha Nutt. -- accepted -- pipestem clematis
  Clematis ligusticifolia Nutt. -- accepted -- hierba de chivo, old-man's-beard, virgin's-bower, virgins bower, virginsbower, western white clematis
  Clematis ligusticifolia var. brevifolia Nutt. -- not accepted -- western white clematis
  Clematis ligusticifolia var. ligusticifolia Nutt. -- not accepted -- deciduous traveler's-joy, western white clematis, white clematis
  Clematis pauciflora Nutt. -- accepted -- ropevine clematis
  Clematis verticillaris var. columbiana (Nutt.) A. Gray -- not accepted
  Clinopodium arkansanum (Nutt.) House -- not accepted -- limestone calamint
  Clinopodium coccineum (Nutt. ex Hook.) Kuntze -- accepted -- scarlet calamint
  Clinopodium glabrum (Nutt.) Kuntze -- accepted -- limestone calamint
  Cneoridium dumosum (Nutt.) Hook. f. ex Baill. -- accepted -- bush rue
  Coelorachis rugosa (Nutt.) Nash -- not accepted -- wrinkled jointtail grass
  Cogswellia foeniculacea (Nutt.) J.M. Coult. & Rose -- not accepted
  Cogswellia macrocarpa (Nutt. ex Torr. & A. Gray) M.E. Jones -- not accepted
  Collinsia Nutt. -- accepted -- blue eyed Mary, blue-eyed Mary
  Collinsia verna Nutt. -- accepted -- blue-eyed Mary, spring blue eyed Mary
  Collinsia violacea Nutt. -- accepted -- violet blue eyed Mary, violet collensia
  Collomia Nutt. -- accepted -- mountain trumpet, trumpet
  Collomia linearis Nutt. -- accepted -- narrow-leaf mountain-trumpet, narrowleaf mountaintrumpet, slenderleaf collomia, tiny trumpet
  Comandra Nutt. -- accepted -- bastard toadflax, toadflax
  Comandra umbellata (L.) Nutt. -- accepted -- bastard toadflax
  Comandra umbellata ssp. umbellata (L.) Nutt. -- accepted -- bastard toadflax
  Conopholis ludoviciana (Nutt.) Alph. Wood -- not accepted
  Conyza canadensis var. pusilla (Nutt.) Cronquist -- not accepted -- Canadian horseweed
  Coptis occidentalis (Nutt.) Torr. & A. Gray -- accepted -- Idaho goldthread
  Corallorhiza multiflora Nutt. -- not accepted
  Corallorhiza odontorhiza (Willd.) Nutt. -- accepted -- autumn coralroot, late coralroot
  Corallorhiza trifida var. verna (Nutt.) Fernald -- not accepted
  Corallorrhiza multiflora Nutt. -- not accepted
  Corallorrhiza trifida var. verna (Nutt.) Fernald -- not accepted
  Cordylanthus Nutt. ex Benth. -- accepted -- bird's beak, bird's-beak
  Cordylanthus capitatus Nutt. ex Benth. -- accepted -- cluster bird'sbeak, Yakima bird's-beak
  Cordylanthus filifolius Nutt. ex Benth. -- not accepted
  Cordylanthus maritimus Nutt. ex Benth. -- not accepted -- saltmarsh bird's-beak, saltmarsh bird'sbeak
  Cordylanthus maritimus ssp. maritimus Nutt. ex Benth. -- not accepted -- salt marsh bird's beak, salt marsh bird's-beak
  Cordylanthus ramosus Nutt. ex Benth. -- accepted -- bushy bird's beak, bushy birdbeak, muchbranched bird'sbeak
  Coreopsis californica (Nutt.) H. Sharsm. -- accepted -- California tickseed, Newberry's tickseed
  Coreopsis californica var. californica (Nutt.) H. Sharsm. -- accepted -- California tickseed
  Coreopsis gladiata var. linifolia (Nutt.) Cronquist -- not accepted
  Coreopsis linifolia Nutt. -- not accepted -- Texas tickseed
  Coreopsis major var. rigida (Nutt.) Boynt. -- not accepted
  Coreopsis major var. stellata (Nutt.) B.L. Rob. -- not accepted
  Coreopsis maritima (Nutt.) Hook. f. -- accepted -- sea dahlia
  Coreopsis nudata Nutt. -- accepted -- Georgia tickseed
  Coreopsis palmata Nutt. -- accepted -- stiff tickseed, wedgeleaf coreopsis
  Coreopsis rosea Nutt. -- accepted -- pink tickseed
  Coreopsis tinctoria Nutt. -- accepted -- Atkinson's tickseed, golden tickseed, plains coreopsis, plains tickseed
  Coreopsis tinctoria var. tinctoria Nutt. -- not accepted -- golden tickseed
  Corethrogyne filaginifolia (Hook. & Arn.) Nutt. -- accepted -- California sandaster, common sandaster, whiteleaf sandaster
  Corethrogyne filaginifolia var. filaginifolia (Hook. & Arn.) Nutt. -- not accepted -- common sandaster
  Corethrogyne filaginifolia var. incana (Nutt.) Canby -- not accepted -- San Diego sandaster
  Corethrogyne incana Nutt. -- not accepted
  Corispermum americanum (Nutt.) Nutt. -- accepted -- American bugseed
  Corispermum americanum var. americanum (Nutt.) Nutt. -- accepted -- American bugseed
  Coryphantha vivipara (Nutt.) Britton & Rose -- not accepted
  Cotinus americanus Nutt. -- not accepted
  Cracca onobrychoides (Nutt.) Kuntze -- not accepted
  Crassina grandiflora (Nutt.) Kuntze -- not accepted
  Crataegus douglasii var. rivularis (Nutt.) Sarg. -- not accepted
  Crataegus nudiflora Nutt. ex Torr. & A. Gray -- not accepted
  Crataegus rivularis Nutt. -- accepted -- river hawthorn
  Crepis acuminata Nutt. -- accepted -- long-leaf hawksbeard, longleaf hawksbeard, tapertip hawksbeard
  Crepis acuminata ssp. acuminata Nutt. -- not accepted -- longleaf hawksbeard, tapertip hawksbeard
  Crepis glauca (Nutt.) Torr. & A. Gray -- not accepted
  Crepis occidentalis Nutt. -- accepted -- large-flower hawk's-beard, largeflower hawksbeard, western hawksbeard
  Crepis occidentalis ssp. occidentalis Nutt. -- accepted -- largeflower hawksbeard
  Crepis runcinata ssp. glauca (Nutt.) Babc. & Stebbins -- accepted -- fiddleleaf hawksbeard
  Crepis runcinata var. glauca (Nutt.) B. Boivin -- not accepted
  Cristatella erosa Nutt. -- not accepted
  Critesion pusillum (Nutt.) Á. Löve -- not accepted
  Croomia pauciflora (Nutt.) Torr. -- accepted -- croomia
  Croptilon divaricatum (Nutt.) Raf. -- accepted -- goldenweed, slender scratchdaisy
  Crossosoma Nutt. -- accepted -- rockflower
  Crossosoma californica Nutt. -- not accepted
  Crossosoma californicum Nutt. -- accepted -- California rockflower
  Croton ellipticus Nutt. -- not accepted
  Croton muricatus Nutt. -- not accepted
  Crypsis squarrosa Nutt. -- not accepted
  Crypsis virginica (L.) Nutt. -- not accepted
  Cunila coccinea Nutt. ex Hook. -- not accepted
  Cymanchum scoparium Nutt. -- not accepted
  Cymbia occidentalis (Nutt.) Standl. -- not accepted
  Cymopterus glaucus Nutt. -- accepted -- smooth springparsley, waxy springparsley
  Cymopterus glomeratus (Nutt.) DC. -- accepted -- plains springparsley
  Cymopterus montanus Nutt. ex Torr. & A. Gray -- accepted -- Montana wavewing, mountain springparsley
  Cymopterus terebinthinus var. foeniculaceus (Nutt. ex Torr. & A. Gray) Cronquist -- not accepted
  Cynanchum scoparium Nutt. -- not accepted -- leafless swallow-wort
  Cyrtorhyncha ranunculina Nutt. -- not accepted
  Dalea aurea Nutt. ex Fraser -- accepted -- golden dalea, golden prairie clover, golden prairie-clover, golden prairieclover, silktop dalea
  Dalea carnea var. gracilis (Nutt.) Barneby -- accepted -- whitetassels
  Dalea enneandra Nutt. ex Fraser -- accepted -- bigtop dalea, nine-anther dalea, nine-anther prairie-clover, nineanther prairie clover, nineanther prairieclover
  Dalea multiflora (Nutt.) Shinners -- accepted -- roundhead prairie clover, Roundhead prairieclover
  Dalea villosa (Nutt.) Spreng. -- accepted -- hairy prairieclover, silky prairie clover, silky prairie-clover, silky prairieclover
  Dalea villosa var. villosa (Nutt.) Spreng. -- accepted -- silky prairie clover, silky prairie-clover, silky prairieclover
  Danthonia sericea Nutt. -- accepted -- downy danthonia
  Danthonia sericea var. sericea Nutt. -- not accepted
  Dasistoma macrophylla (Nutt.) Raf. -- accepted -- mullein foxglove, mullein seymeria
  Dasistoma pectinata (Nutt.) Benth. -- not accepted
  Deinandra corymbosa ssp. macrocephala (Nutt.) B.G. Baldw. -- not accepted
  Delopyrum gracile (Nutt.) Small -- not accepted
  Delphinium bicolor Nutt. -- accepted -- little larkspur
  Delphinium bicolor ssp. bicolor Nutt. -- accepted -- little larkspur
  Delphinium carolinianum ssp. virescens (Nutt.) R.E. Brooks -- accepted -- Carolina larkspur, plains larkspur, white larkspur
  Delphinium depauperatum Nutt. -- accepted -- slim larkspur, wand larkspur
  Delphinium nuttallii ssp. ochroleucum (Nutt.) M.J. Warnock -- accepted -- upland larkspur
  Delphinium virescens Nutt. -- not accepted -- Carolina larkspur, plains larkspur, prairie larkspur
  Dentaria californica Nutt. -- not accepted
  Dentaria californica var. integrifolia (Nutt.) Detling -- not accepted
  Dentaria heterophylla Nutt. -- not accepted
  Dentaria integrifolia Nutt. -- not accepted
  Dentaria integrifolia var. californica (Nutt.) Jeps. -- not accepted
  Dentaria maxima Nutt. -- not accepted
  Descurainia richardsonii var. brevipes (Nutt.) S.L. Welsh & Reveal -- not accepted
  Desmatodon hendersonii (Ren. & Card.) Williams in Millsp. & Nutt. -- not accepted
  Desmodium laevigatum (Nutt.) DC. -- accepted -- smooth tickclover, smooth ticktrefoil
  Desmodium pauciflorum (Nutt.) DC. -- accepted -- fewflower ticktrefoil, fewflowered tickclover
  Deyeuxia alopecuroides Nutt. ex A. Gray -- not accepted
  Diachroa Nutt. -- not accepted
  Diachroa maritima Nutt. ex Steud. -- not accepted
  Diachroa procumbens (Muhl.) Nutt. -- not accepted
  Diamorpha Nutt. -- accepted
  Diamorpha cymosa (Nutt.) Britton ex Small -- not accepted
  Diaperia Nutt. -- accepted
  Diaperia multicaulis (DC.) Nutt. -- not accepted
  Diaperia prolifera (Nutt. ex DC.) Nutt. -- accepted -- big-head rabbit-tobacco, bighead pygmycudweed
  Diaperia prolifera var. prolifera (Nutt. ex DC.) Nutt. -- accepted -- big-head rabbit-tobacco, bighead pygmycudweed
  Didiplis diandra (Nutt. ex DC.) Alph. Wood -- accepted -- waterpurslane
  Dieteria Nutt. -- accepted
  Dieteria canescens (Pursh) Nutt. -- accepted -- hoary tansyaster, hoary-aster
  Dieteria canescens var. canescens (Pursh) Nutt. -- accepted
  Dieteria canescens var. sessiliflora (Nutt.) D.R. Morgan & R.L. Hartm. -- accepted -- hoary tansyaster
  Dieteria divaricata Nutt. -- not accepted
  Dieteria gracilis Nutt. non Aster gracilis Nutt. -- not accepted
  Dieteria pulverulenta Nutt. -- not accepted
  Dieteria sessiliflora (Nutt.) Greene -- not accepted
  Dieteria spinulosa (Pursh) Nutt. -- not accepted
  Dieteria viscosa Nutt. -- not accepted
  Diospyros virginiana var. pubescens Nutt. -- not accepted
  Diplacus Nutt. -- accepted -- bush monkeyflower
  Diplacus glutinosus (J.C. Wendl.) Nutt. -- not accepted
  Diplacus glutinosus var. puniceus (Nutt.) Benth. -- not accepted
  Diplacus latifolius Nutt. -- not accepted
  Diplacus leptanthus Nutt. -- not accepted
  Diplacus longiflorus Nutt. -- accepted -- southern bush monkeyflower
  Diplacus puniceus Nutt. -- accepted -- red bush monkeyflower
  Dissanthelium californica (Nutt.) Benth. -- not accepted
  Dissanthelium californicum (Nutt.) Benth. -- accepted -- Catalina grass
  Ditaxis mercurialina (Nutt.) J.M. Coult. -- accepted -- tall silverbush
  Dodecatheon puberulum (Nutt.) Piper -- not accepted
  Dolicholus latifolius (Nutt. ex Torr. & A. Gray) Vail -- not accepted
  Draba brachycarpa Nutt. ex Torr. & A. Gray -- accepted -- short-pod whitlowgrass, shortfruited draba, shortpod draba
  Draba cuneifolia Nutt. ex Torr. & A. Gray -- accepted -- wedgeleaf draba, wedgeleaf whitlowgrass
  Draba cuneifolia var. cuneifolia Nutt. ex Torr. & A. Gray -- accepted -- wedgeleaf draba, wedgeleaf whitlowgrass
  Draba densifolia Nutt. -- accepted -- denseleaf draba
  Draba micrantha Nutt. -- not accepted
  Draba reptans var. micrantha (Nutt.) Fernald -- not accepted
  Dracocephalum intermedium Nutt. -- not accepted
  Dracocephalum parviflorum Nutt. -- accepted -- American dragonhead
  Drymocallis fissa (Nutt.) Rydb. -- accepted -- bigflower cinquefoil
  Dudleya edulis (Nutt.) Moran -- accepted -- fingertips
  Dudleya lanceolata (Nutt.) Britton & Rose -- accepted -- lanceleaf liveforever
  Dudleya pulverulenta (Nutt.) Britton & Rose -- accepted -- chalk dudleya, chalk liveforever
  Dudleya pulverulenta ssp. pulverulenta (Nutt.) Britton & Rose -- not accepted -- chalk dudleya
  Echeveria pulverulenta Nutt. -- not accepted
  Echinacea atrorubens Nutt. -- accepted -- Topeka purple coneflower, yellowsampson
  Echinacea pallida (Nutt.) Nutt. -- accepted -- pale echinacea, pale purple coneflower, purple coneflower
  Echinacea pallida var. sanguinea (Nutt.) Gandhi & R.D. Thomas -- not accepted
  Echinacea sanguinea Nutt. -- accepted -- sanguin purple coneflower
  Echinodorus radicans (Nutt.) Engelm. -- not accepted
  Echinodorus rostratus (Nutt.) Engelm. -- not accepted
  Elatine minima (Nutt.) Fisch. & C.A. Mey. -- accepted -- small waterwort
  Elephantopus carolinianus var. simplex Nutt. -- not accepted
  Elymus difformis Nutt. ex J.G. Sm. -- not accepted
  Elymus hystrix (Nutt.) M.E. Jones -- not accepted
  Encelia californica Nutt. -- accepted -- California brittlebush
  Endodeca serpentaria var. hastata (Nutt.) C.F. Reed -- not accepted
  Endolepis dioica (Nutt.) Standl. -- not accepted -- scurfless saltbush, Suckley's endolepis, Suckley's saltbush
  Endorima uniflora (Nutt.) Raf. -- not accepted
  Engelmannia A. Gray ex Nutt. -- accepted -- Engelmann's daisy, engelmannia
  Engelmannia pinnatifida A. Gray ex Nutt. -- not accepted -- Engelmann's daisy
  Enslenia albida Nutt. -- not accepted
  Epallageiton glaucum (Nutt.) Koso-Pol. -- not accepted
  Epifagus Nutt. -- accepted -- beechdrops
  Epilobium glaberrimum ssp. fastigiatum (Nutt.) Hoch & P.H. Raven -- accepted -- glaucus willowherb, smooth willowweed
  Epilobium glaberrimum var. fastigiatum (Nutt.) Trel. ex Jeps. -- not accepted
  Epilobium paniculatum Nutt. ex Torr. & A. Gray -- not accepted
  Epilobium paniculatum var. paniculatum Nutt. ex Torr. & A. Gray -- not accepted
  Epilobium suffruticosum Nutt. -- accepted -- shrubby willowherb
  Eragrostis capitata (Nutt.) Nash -- not accepted
  Eragrostis interrupta (Nutt.) Branner & Coville -- not accepted
  Eragrostis trichodes (Nutt.) Alph. Wood -- accepted -- sand lovegrass
  Eragrostis trichodes var. trichodes (Nutt.) Alph. Wood -- not accepted -- sand lovegrass
  Eremogone congesta (Nutt.) Ikonn. -- accepted -- ballhead sandwort
  Eremogone congesta var. congesta (Nutt.) Ikonn. -- accepted -- ballhead sandwort
  Eremogone hookeri (Nutt.) W.A. Weber -- accepted -- Hooker's sandwort
  Eremogone hookeri var. hookeri (Nutt.) W.A. Weber -- accepted -- Hooker's sandwort
  Eriastrum filifolium (Nutt.) Wooton & Standl. -- accepted -- lavender woollystar
  Ericameria Nutt. -- accepted -- goldenbush, heath goldenrod, heathgoldenrod
  Ericameria depressa (Nutt.) L.C. Anderson -- not accepted
  Ericameria discoidea (Nutt.) G.L. Nesom -- accepted -- whitestem goldenbush
  Ericameria discoidea var. discoidea (Nutt.) G.L. Nesom -- accepted -- discoid goldenbush, whitestem goldenbush
  Ericameria nana Nutt. -- accepted -- dwarf goldenbush, low goldenbush
  Ericameria nauseosa ssp. nauseosa var. speciosa (Nutt.) G.L. Nesom & Baird -- not accepted -- gray rubber rabbitbrush
  Ericameria nauseosa var. graveolens (Nutt.) Reveal & Schuyler -- accepted -- rubber rabbitbrush
  Ericameria nauseosa var. speciosa (Nutt.) G.L. Nesom & Baird -- accepted -- rubber rabbitbrush
  Ericameria resinosa Nutt. -- accepted -- Columbian goldenbush
  Ericameria suffruticosa (Nutt.) G.L. Nesom -- accepted -- bighead goldenbush, single-head heath-goldenrod, singlehead goldenbush
  Ericameria viscidiflora ssp. lanceolata (Nutt.) L.C. Anderson -- not accepted
  Erigenia Nutt. -- accepted
  Erigenia bulbosa (Michx.) Nutt. -- accepted -- harbinger of spring
  Erigeron asper Nutt. -- not accepted -- rough fleabane
  Erigeron asperum Nutt. -- not accepted
  Erigeron bellidiastrum Nutt. -- accepted -- western daisy fleabane, western fleabane
  Erigeron bellidiastrum var. bellidiastrum Nutt. -- accepted -- western daisy fleabane
  Erigeron caespitosus Nutt. -- accepted -- tufted fleabane
  Erigeron canadensis var. pusillus (Nutt.) B. Boivin, non H.E. Ahles -- not accepted
  Erigeron corymbosus Nutt. -- accepted -- longleaf fleabane
  Erigeron decumbens Nutt. -- accepted -- Willamette fleabane
  Erigeron decumbens var. decumbens Nutt. -- accepted -- Willamette daisy, Willamette fleabane
  Erigeron filifolius (Hook.) Nutt. -- accepted -- threadleaf daisy, threadleaf fleabane
  Erigeron filifolius var. filifolius (Hook.) Nutt. -- not accepted -- threadleaf daisy, threadleaf fleabane
  Erigeron filiosus Nutt. -- not accepted
  Erigeron foliosus Nutt. -- accepted -- leafy fleabane
  Erigeron foliosus var. foliosus Nutt. -- accepted -- leafy fleabane
  Erigeron foliosus var. stenophyllus (Nutt.) A. Gray -- not accepted
  Erigeron glabellus Nutt. -- accepted -- smooth fleabane, streamside fleabane
  Erigeron glabellus var. glabellus Nutt. -- accepted -- rough fleabane, streamside fleabane
  Erigeron glacialis (Nutt.) A. Nelson -- accepted -- subalpine fleabane
  Erigeron glacialis var. glacialis (Nutt.) A. Nelson -- accepted -- subalpine fleabane
  Erigeron macranthus Nutt. -- not accepted
  Erigeron nanus Nutt. -- accepted -- dwarf fleabane
  Erigeron nivalis Nutt. -- accepted -- bitter daisy, bitter fleabane, blue fleabane
  Erigeron ochroleucus Nutt. -- accepted -- buff fleabane
  Erigeron ochroleucus var. ochroleucus Nutt. -- accepted -- buff fleabane
  Erigeron pumilus Nutt. -- accepted -- low daisy, low fleabane, shaggy fleabane
  Erigeron pumilus ssp. pumilus Nutt. -- not accepted -- shaggy fleabane
  Erigeron pumilus var. pumilus Nutt. -- accepted -- shaggy fleabane
  Erigeron pusillus Nutt. -- not accepted
  Erigeron speciosus var. macranthus (Nutt.) Cronquist -- not accepted -- aspen daisy, aspen fleabane
  Eriocarpum grindelioides Nutt. -- not accepted
  Eriocoma Nutt. -- not accepted
  Eriocoma cuspidata Nutt. -- not accepted
  Eriodictyon angustifolium Nutt. -- accepted -- narrowleaf yerba santa, yerba santa
  Eriogonum acaule Nutt. -- accepted -- pointed eriogonum, singlestem buckwheat
  Eriogonum angustifolium Nutt. -- not accepted
  Eriogonum annuum Nutt. -- accepted -- annual buckwheat, annual eriogonum, annual wild buckwheat, annual wildbuckwheat, umbrella plant, wild buckwheat
  Eriogonum brevicaule Nutt. -- accepted -- shortstem buckwheat
  Eriogonum brevicaule var. brevicaule Nutt. -- accepted -- shortstem buckwheat
  Eriogonum brevicaule var. micranthum (Nutt.) Reveal -- accepted -- shortstem buckwheat
  Eriogonum caespitosum Nutt. -- accepted -- mat buckwheat, mat eriogonum, matted buckwheat, matted wild buckwheat
  Eriogonum caespitosum var. acaule (Nutt.) R.J. Davis -- not accepted
  Eriogonum campanulatum Nutt. -- not accepted
  Eriogonum cernuum Nutt. -- accepted -- nodding buckwheat, nodding eriogonum, nodding wild buckwheat
  Eriogonum cernuum var. cernum Nutt. -- not accepted
  Eriogonum cernuum var. cernuum Nutt. -- not accepted -- nodding buckwheat, nodding wild buckwheat
  Eriogonum dendroideum (Nutt.) S. Stokes -- not accepted
  Eriogonum dendroideum var. foliosum (Nutt.) M.E. Jones -- not accepted
  Eriogonum effusum Nutt. -- accepted -- buckwheat eriogonum, spreading buckwheat
  Eriogonum effusum var. effusum Nutt. -- not accepted -- spreading buckwheat
  Eriogonum fasciculatum ssp. foliolosum (Nutt.) S. Stokes -- not accepted
  Eriogonum fasciculatum var. foliolosum (Nutt.) S. Stokes ex Abrams -- accepted -- Eastern Mojave buckwheat
  Eriogonum flavum Nutt. -- accepted -- alpine golden buckwheat, yellow eriogonum
  Eriogonum flavum var. flavum Nutt. -- accepted -- alpine golden buckwheat
  Eriogonum glandulosum (Nutt.) Nutt. ex Benth. -- accepted -- acorn buckwheat, Gambel's buckwheat
  Eriogonum heracleoides Nutt. -- accepted -- parsnipflower buckwheat, Wyeth's buckwheat, Wyeth's eriogonum
  Eriogonum heracleoides var. angustifolium (Nutt.) Torr. & A. Gray -- not accepted -- parsnipflower buckwheat
  Eriogonum heracleoides var. heracleoides Nutt. -- accepted -- parsnipflower buckwheat
  Eriogonum longifolium Nutt. -- accepted -- longleaf buckwheat, longleaf eriogonum, longleaf wildbuckwheat
  Eriogonum longifolium var. longifolium Nutt. -- accepted -- longleaf buckwheat
  Eriogonum microthecum Nutt. -- accepted -- slender buckwheat, slenderbush buckwheat, slenderbush eriogonum
  Eriogonum microthecum var. effusum (Nutt.) Torr. & A. Gray -- not accepted
  Eriogonum microthecum var. microthecum Nutt. -- accepted -- slender buckwheat
  Eriogonum ovalifolium Nutt. -- accepted -- cushion buckwheat, cushion wild buckwheat, ovalleaf eriogonum
  Eriogonum ovalifolium var. ovalifolium Nutt. -- accepted -- cushion buckwheat, cushion wild buckwheat
  Eriogonum ovalifolium var. purpureum (Nutt.) Durand -- accepted -- cushion buckwheat
  Eriogonum racemosum Nutt. -- accepted -- redroot buckwheat
  Eriogonum racemosum var. racemosum Nutt. -- not accepted
  Eriogonum rosmarinifolium var. foliolosum Nutt. -- not accepted
  Eriogonum salsuginosum (Nutt.) Hook. -- not accepted
  Eriogonum sphaerocephalum var. geniculatum (Nutt.) S. Stokes -- not accepted
  Eriogonum sphaerocephalum var. megacephalum (Nutt.) S. Stokes ex M.E. Jones -- not accepted
  Eriogonum umbellatum var. ellipticum (Nutt.) Reveal -- accepted -- sulphur-flower buckwheat
  Eriogynia caespitosa (Nutt.) S. Watson -- not accepted
  Eriophorum tenellum Nutt. -- accepted -- fewnerved cottongrass
  Eryngium prostratum Nutt. ex DC. -- accepted -- creeping eryngo
  Erysimum arkansanum Nutt. -- not accepted
  Erysimum asperum (Nutt.) DC. -- accepted -- western wallflower
  Erysimum asperum var. arkansanum (Nutt.) A. Gray -- not accepted
  Erysimum elatum Nutt. -- not accepted
  Erysimum parviflorum Nutt. -- not accepted
  Erythremia grandiflora Nutt. -- not accepted
  Erythronium albidum Nutt. -- accepted -- small white fawnlily, white fawnlily
  Escobaria vivipara (Nutt.) Buxb. -- accepted -- spinystar
  Escobaria vivipara var. vivipara (Nutt.) Buxb. -- not accepted -- pink pincushion cactus, spinystar, spinystar cactus
  Espeletia amplexicaulis Nutt. -- not accepted
  Eubotrys Nutt. -- accepted
  Eubotrys racemosa (L.) Nutt. -- accepted -- coastal fetterbush, swamp doghobble
  Eucephalus Nutt. -- accepted -- aster, eucephalus
  Eucephalus elegans Nutt. -- accepted -- elegant aster
  Eucephalus glaucus Nutt. -- not accepted
  Eucrypta Nutt. -- accepted -- hideseed
  Eulobus Nutt. ex Torr. & A. Gray -- accepted
  Eulobus californicus Nutt. ex Torr. & A. Gray -- accepted -- California suncup
  Eulophus americanus Nutt. ex DC. -- not accepted
  Euonymus obovata Nutt. -- not accepted -- running strawberry bush
  Euonymus obovatus Nutt. -- accepted -- running strawberry bush
  Euonymus occidentale Nutt. ex Torr. -- not accepted -- western burning bush, western wahoo
  Euonymus occidentale var. occidentale Nutt. ex Torr. -- not accepted -- western burning bush
  Euonymus occidentalis Nutt. ex Torr. -- accepted -- western burning bush, western burningbush, western wahoo
  Euonymus occidentalis var. occidentalis Nutt. ex Torr. -- accepted -- western burning bush
  Euphorbia annulata Nutt. ex Sherff -- not accepted
  Euphorbia arenaria Nutt. -- not accepted
  Euphorbia herniarioides Nutt. -- not accepted
  Euphorbia heterantha Nutt. -- not accepted
  Euphorbia hexagona Nutt. ex Spreng. -- accepted -- six-angle spurge, sixangle spurge
  Euphorbia maritima Nutt. -- not accepted
  Euphorbia pauciflora Nutt. ex Seem. -- not accepted
  Euphorbia peploides Nutt. -- not accepted
  Euploca Nutt. -- accepted
  Euploca convolvulacea Nutt. -- accepted -- bindweed heliotrope, phlox heliotrope, wide-flower heliotrope
  Euploca convolvulacea ssp. convolvulacea Nutt. -- accepted -- phlox heliotrope
  Eurybia glauca (Nutt.) G.L. Nesom -- not accepted -- gray aster
  Eurybia integrifolia (Nutt.) G.L. Nesom -- accepted -- thickstem aster
  Euthamia Nutt. ex Cass. -- accepted -- goldentop
  Euthamia graminifolia (L.) Nutt. -- accepted -- flat-top goldentop, flattop goldentop, slender goldentop
  Euthamia graminifolia var. graminifolia (L.) Nutt. -- not accepted -- flat-top goldentop
  Euthamia occidentalis Nutt. -- accepted -- western goldenrod, western goldentop
  Euthamia tenuifolia (Pursh) Nutt. -- not accepted -- slender goldentop
  Euthamia tenuifolia var. tenuifolia (Pursh) Nutt. -- not accepted -- slender goldentop
  Eutriana oligostachya (Nutt.) Kunth -- not accepted
  Evax prolifera Nutt. ex DC. -- not accepted -- bighead pygmycudweed, rabbit tobacco, rabbit's tobacco
  Evolvulus pilosus Nutt. -- not accepted
  Festuca megalura Nutt. -- not accepted
  Festuca microstachys Nutt. -- not accepted
  Festuca microstachys var. microstachys Nutt. -- not accepted
  Festuca octoflora var. glauca (Nutt.) Fernald -- not accepted
  Festuca sciurea Nutt. -- not accepted
  Festuca spicata Nutt. -- not accepted
  Festuca tenella var. glauca Nutt. -- not accepted
  Ficus aurea Nutt. -- accepted -- Florida strangler, Florida strangler fig
  Ficus brevifolia Nutt. -- not accepted
  Filaginella palustris (Nutt.) Holub -- not accepted
  Filago californica Nutt. -- not accepted -- California cottonrose, California fluffweed
  Filago prolifera (Nutt. ex DC.) Britton non Pomel -- not accepted
  Forestiera pubescens Nutt. -- accepted -- desert olive, downy forestiera, elbowbush, stretchberry
  Forestiera pubescens var. pubescens Nutt. -- accepted -- New Mexico forestiera, New Mexico olive, stretchberry
  Fragaria cuneifolia Nutt. ex Howell -- not accepted
  Fragaria X ananassa ssp. cuneifolia (Nutt. ex Howell) Staudt (pro nm.) -- accepted
  Fragaria X ananassa var. cuneifolia (Nutt. ex Howell) Staudt -- not accepted -- hybrid strawberry
  Franseria discolor Nutt. -- not accepted -- skeletonleaf bursage
  Franseria pumila Nutt. -- not accepted
  Franseria tomentosa (Nutt.) A. Nelson, non A. Gray -- not accepted -- bur ragweed
  Fraxinus oregona Nutt. -- not accepted
  Fraxinus pauciflora Nutt. -- not accepted
  Fraxinus pennsylvanica ssp. oregona (Nutt.) G.N. Mill. -- not accepted
  Fritillaria atropurpurea Nutt. -- accepted -- leopard lily, spotted fritillary, spotted missionbells
  Froelichia floridana (Nutt.) Moq. -- accepted -- cottonweed, field snakecotton, Florida snakecotton, plains snakecotton, prairie froelichia
  Froelichia floridana var. floridana (Nutt.) Moq. -- not accepted -- plains snakecotton
  Gaertneria discolor (Nutt.) Kuntze -- not accepted
  Gaertneria tomentosa (Nutt.) A. Heller -- not accepted
  Galactia elliotii Nutt. -- not accepted
  Galactia elliottii Nutt. -- accepted -- Elliott's milkpea
  Galium angustifolium Nutt. ex Torr. & A. Gray -- accepted -- narrowleaf bedstraw
  Galium angustifolium ssp. angustifolium Nutt. ex A. Gray -- accepted -- narrowleaf bedstraw
  Galium californicum var. crebrifolium Nutt. -- not accepted
  Galium suffruticosum Nutt. -- not accepted
  Galium trichocarpum Nutt. -- not accepted
  Galium virgatum Nutt. -- accepted -- southwest bedstraw, southwestern bedstraw
  Galvezia speciosa (Nutt.) A. Gray -- not accepted -- island snapdragon
  Gambelia Nutt. -- accepted -- greenbright
  Gambelia speciosa Nutt. -- accepted -- showy greenbright
  Gamochaeta ustulata (Nutt.) G.L. Nesom -- accepted -- featherweed
  Garberia fruticosa (Nutt.) A. Gray -- not accepted
  Gaura coccinea Nutt. ex Pursh -- not accepted -- scarlet beeblossom, scarlet gaura, Scarlet guara
  Gaura sinuata Nutt. ex Ser. -- not accepted -- wavyleaf beeblossom, wavyleaf gaura
  Geoprumnon crassicarpum (Nutt.) Rydb. -- not accepted
  Geoprumnon plattense (Nutt.) Rydb. -- not accepted
  Gerardia aphylla Nutt. -- not accepted
  Gerardia filifolia Nutt. -- not accepted
  Gerardia heterophylla Nutt. -- not accepted
  Gerardia linifolia Nutt. -- not accepted
  Gerardia longifolia Nutt. -- not accepted
  Gerardia pectinata (Nutt.) Benth. -- not accepted
  Gerardia pedicularia var. pectinata Nutt. -- not accepted
  Gerardia tenuifolia ssp. parviflora (Nutt.) Pennell -- not accepted
  Gerardia tenuifolia var. parviflora Nutt. -- not accepted
  Gilia capitata ssp. abrotanifolia (Nutt. ex Greene) V.E. Grant -- accepted -- bluehead gilia
  Gilia congesta var. crebrifolia (Nutt.) A. Gray -- not accepted
  Gilia crebrifolia Nutt. -- not accepted
  Gilia filifolia Nutt. -- not accepted
  Gilia multiflora Nutt. -- not accepted
  Gilia pinnatifida Nutt. ex A. Gray -- not accepted -- sticky gilia
  Gilia pumila Nutt. -- not accepted
  Gilia spicata Nutt. -- not accepted
  Gillenia stipulata (Muhl. ex Willd.) Nutt. -- accepted -- American ipecac, Indian physic
  Githopsis Nutt. -- accepted -- bluecup
  Githopsis specularioides Nutt. -- accepted -- common bluecup
  Githopsis specularioides var. hirsuta Nutt. -- not accepted
  Githopsis specularioides var. specularioides Nutt. -- not accepted
  Glandularia bipinnatifida (Nutt.) Nutt. -- accepted -- Dakota mock vervain
  Glandularia bipinnatifida var. bipinnatifida (Nutt.) Nutt. -- accepted -- Dakota mock vervain, Dakota verbena
  Glandularia canadensis (L.) Nutt. -- accepted -- rose mock vervain, rose verbena
  Glyceria airoides (Nutt.) Fries -- not accepted
  Glyceria repanda Nutt. -- not accepted
  Glycosma occidentalis Nutt. ex Torr. & A. Gray -- not accepted
  Glycyrrhiza glutinosa Nutt. -- not accepted
  Glycyrrhiza lepidota var. glutinosa (Nutt.) S. Watson -- not accepted
  Gnaphalium canescens ssp. microcephalum (Nutt.) Stebbins & Keil -- not accepted
  Gnaphalium dimorphum Nutt. -- not accepted
  Gnaphalium microcephalum Nutt. -- not accepted
  Gnaphalium palustre Nutt. -- accepted -- cudweed, lowland cudweed, marsh everlasting, western marsh cudweed
  Gnaphalium purpureum var. ustulatum (Nutt.) B. Boivin -- not accepted
  Gnaphalium ramosissimum Nutt. -- not accepted
  Gnaphalium ustulatum Nutt. -- not accepted
  Godetia epilobioides (Nutt. ex Torr. & A. Gray) S. Watson -- not accepted
  Gormania oregana (Nutt.) Britton -- not accepted
  Gossypium tomentosum Nutt. ex Seem. -- accepted -- Hawai'i cotton, Hawaiian cotton, mao
  Gossypium tormentosum Nutt. -- not accepted
  Gratiola floridana Nutt. -- accepted -- Florida hedgehyssop
  Greenia Nutt. -- not accepted
  Greenia arkansana Nutt. -- not accepted
  Grindelia ciliata (Nutt.) Spreng. -- accepted -- Spanish gold
  Grindelia lanceolata Nutt. -- accepted -- Gulf gumweed, narrowleaf gumweed, spiny toothed gumweed, Texan gumweed
  Grindelia lanceolata var. lanceolata Nutt. -- not accepted -- narrowleaf gumweed
  Grindelia nana Nutt. -- not accepted -- Idaho gumweed
  Grindelia nana var. discoidea (Nutt.) A. Gray -- not accepted
  Grindelia nana var. integrifolia Nutt. -- not accepted
  Grindelia nana var. nana Nutt. -- not accepted -- Idaho gumweed
  Grindelia robusta Nutt. -- not accepted
  Grindelia robusta var. robusta Nutt. -- not accepted -- shore gumweed
  Grindelia squarrosa var. integrifolia (Nutt.) B. Boivin -- not accepted
  Grindelia texana var. lanceolata (Nutt.) Shinners -- not accepted
  Grossularia missouriensis (Nutt.) Coville & Britton -- not accepted
  Gymnadeniopsis integra (Nutt.) Rydb. -- accepted -- yellow fringeless orchid
  Gymnadeniopsis nivea (Nutt.) Rydb. -- accepted -- snowy orchid
  Habenaria huronensis (Nutt.) Spreng. -- not accepted
  Habenaria hyperborea var. huronensis (Nutt.) Farw. -- not accepted
  Habenaria integra (Nutt.) Spreng. -- not accepted
  Habenaria leucophaea (Nutt.) A. Gray -- not accepted
  Habenaria nivea (Nutt.) Spreng. -- not accepted
  Habenaria repens Nutt. -- accepted -- Habenaria acuática, waterspider bog orchid, waterspider false reinorchid
  Habenaria scutellata (Nutt.) F. Morris -- not accepted
  Hackelia patens (Nutt.) I.M. Johnst. -- accepted -- common stickseed, spotted stickseed
  Hackelia patens var. patens (Nutt.) I.M. Johnst. -- accepted -- spotted stickseed
  Halimolobos virgata (Nutt.) O.E. Schulz -- not accepted -- rod halimolobos, stemmy halimolobos
  Hamamelis virginiana var. macrophylla (Pursh) Nutt. -- not accepted
  Hamamelis virginiana var. parvifolia Nutt. -- not accepted
  Haplopappus acaulis (Nutt.) A. Gray -- not accepted
  Haplopappus armerioides (Nutt.) A. Gray -- not accepted
  Haplopappus ciliatus (Nutt.) DC. -- not accepted -- Spanish gold, waxed goldenweed
  Haplopappus divaricatus (Nutt.) A. Gray -- not accepted
  Haplopappus gracilis (Nutt.) A. Gray -- not accepted
  Haplopappus macronema (Nutt.) A. Gray -- not accepted
  Haplopappus multicaulis (Nutt.) A. Gray -- not accepted
  Haplopappus nanus (Nutt.) D.C. Eaton -- not accepted
  Haplopappus racemosus (Nutt.) Torr. -- not accepted
  Haplopappus racemosus ssp. glomeratus (Nutt.) H.M. Hall -- not accepted
  Haplopappus racemosus var. glomerellus (Nutt.) A. Gray -- not accepted
  Haplopappus racemosus var. paniculatus (Nutt.) Cronquist -- not accepted
  Haplopappus racemosus var. racemosus (Nutt.) Torr. -- not accepted
  Haplopappus radiatus (Nutt.) Cronquist -- not accepted
  Haplopappus resinosus (Nutt.) A. Gray -- not accepted
  Haplopappus suffruticosus (Nutt.) A. Gray -- not accepted
  Haplopappus venetus ssp. vernonioides (Nutt.) H.M. Hall -- not accepted
  Hartmannia speciosa (Nutt.) Small -- not accepted
  Hedeoma arkansana Nutt. -- not accepted
  Hedeoma ciliata Nutt. -- not accepted
  Hedeoma glabra Nutt. -- not accepted
  Hedyotis longifolia var. tenuifolia (Nutt.) Torr. & A. Gray -- not accepted
  Hedyotis purpurea var. tenuifolia (Nutt.) Fosberg -- not accepted
  Hedysarum boreale Nutt. -- accepted -- boreal sweet-vetch, boreal sweetvetch, northern sweetvetch, sweetvetch, Utah sweetvetch
  Hedysarum boreale ssp. boreale Nutt. -- accepted -- boreal sweet-vetch, boreal sweetvetch, northern sweetvetch, Utah sweetvetch
  Hedysarum boreale ssp. boreale var. boreale Nutt. -- not accepted -- boreal sweet-vetch, boreal sweetvetch
  Hedysarum boreale var. boreale Nutt. -- accepted -- boreal sweetvetch, northern sweetvetch, Utah sweetvetch
  Helenium autumnale var. grandiflorum (Nutt.) Torr. & A. Gray -- not accepted -- fall sneezeweed
  Helenium autumnale var. montanum (Nutt.) Fernald -- not accepted -- mountain sneezeweed
  Helenium autumnale var. parviflorum (Nutt.) Fernald -- not accepted -- smallflower sneezeweed
  Helenium brevifolium (Nutt.) Alph. Wood -- accepted -- shortleaf sneezeweed
  Helenium helenium (Nutt.) Small -- not accepted
  Helenium montanum Nutt. -- not accepted
  Helenium nudiflorum Nutt. -- not accepted
  Helenium parviflorum Nutt. -- not accepted
  Helenium pinnatifidum (Nutt.) Rydb. -- accepted -- southeastern sneezeweed
  Helenium tenuifolium Nutt. -- not accepted
  Helianthella uniflora (Nutt.) Torr. & A. Gray -- accepted -- oneflower helianthella
  Helianthella uniflora var. uniflora (Nutt.) Torr. & A. Gray -- not accepted -- oneflower helianthella
  Helianthemum capitatum Nutt. ex Engelm. & A. Gray -- not accepted
  Helianthemum scoparium Nutt. ex Torr. & A. Gray -- accepted -- Bisbee Peak rushrose
  Helianthus debilis Nutt. -- accepted -- cucumberleaf sunflower
  Helianthus debilis ssp. debilis Nutt. -- accepted -- cucumberleaf sunflower
  Helianthus heterophyllus Nutt. -- accepted -- variableleaf sunflower
  Helianthus pauciflorus Nutt. -- accepted -- stiff sunflower
  Helianthus pauciflorus ssp. pauciflorus Nutt. -- accepted -- stiff sunflower
  Helianthus petiolaris Nutt. -- accepted -- prairie sunflower, showy sunflower
  Helianthus petiolaris ssp. petiolaris Nutt. -- accepted -- prairie sunflower
  Helianthus pumilus Nutt. -- accepted -- little sunflower
  Helianthus silphioides Nutt. -- accepted -- rosinweed sunflower
  Helianthus uniflorus Nutt. -- not accepted
  Heliomeris Nutt. -- accepted -- false goldeneye, heliomeris
  Heliomeris multiflora Nutt. -- accepted -- showy goldeneye, showy goldeneyes
  Heliomeris multiflora var. multiflora Nutt. -- accepted -- showy goldeneye, showy goldeneyes
  Heliopsis gracilis Nutt. -- accepted -- smooth oxeye
  Heliopsis helianthoides var. gracilis (Nutt.) Gandhi & R.D. Thomas -- not accepted -- smooth oxeye
  Heliotropium convolvulaceum (Nutt.) A. Gray -- not accepted -- bindweed heliotrope, phlox heliotrope, wide-flower heliotrope
  Heliotropium convolvulaceum var. convolvulaceum (Nutt.) A. Gray -- not accepted -- phlox heliotrope
  Heliotropium tenellum (Nutt.) Torr. -- accepted -- pasture heliotrope
  Helonias paniculatus Nutt. -- not accepted
  Hemarthria rugosa (Nutt.) Kunth -- not accepted
  Hemianthus Nutt. -- not accepted
  Hemianthus micranthemoides Nutt. -- not accepted
  Hemizonia corymbosa ssp. macrocephala (Nutt.) D.D. Keck -- not accepted -- coastal tarweed
  Hemizonia tenella (Nutt.) A. Gray -- not accepted
  Herrickia glauca (Nutt.) Brouillet -- accepted -- Gray's aster
  Herrickia glauca var. glauca (Nutt.) Brouillet -- accepted -- Gray's aster
  Heterocodon Nutt. -- accepted
  Heterocodon rariflorum Nutt. -- not accepted -- rareflower heterocodon, western pearlflower
  Heterocodon rariflorus Nutt. -- accepted -- rareflower heterocodon
  Heterotheca foliosa (Nutt.) Shinners -- not accepted
  Heterotheca grandiflora Nutt. -- accepted -- telegraph weed, telegraphweed
  Heterotheca hyssopifolia (Nutt.) R.W. Long -- not accepted
  Heterotheca oregona (Nutt.) Shinners -- accepted -- Oregon false goldenaster
  Heterotheca oregona var. oregona (Nutt.) Shinners -- accepted -- Oregon false goldenaster
  Heterotheca pilosa (Nutt.) Shinners -- not accepted
  Heterotheca sessiliflora (Nutt.) Shinners -- accepted -- sessileflower false goldenaster
  Heterotheca sessiliflora ssp. sessiliflora (Nutt.) Shinners -- accepted -- sessileflower false goldenaster
  Heterotheca trichophylla (Nutt.) Shinners -- not accepted
  Heterotheca villosa var. foliosa (Nutt.) V.L. Harms -- accepted -- hairy false goldenaster
  Heuchera parvifolia Nutt. ex Torr. & A. Gray -- accepted -- common alumroot, little-leaf alumroot, littleleaf alumroot
  Heuchera parvifolia var. parvifolia Nutt. ex Torr. & A. Gray -- not accepted -- littleleaf alumroot
  Hieracium argutum Nutt. -- accepted -- southern hawkweed
  Hieracium argutum var. argutum Nutt. -- not accepted -- southern hawkweed
  Holmgrenia andina (Nutt.) W.L. Wagner & Hoch -- not accepted -- Blackfoot River evening primrose
  Holodiscus dumosus (Nutt. ex Hook.) A. Heller -- not accepted -- bush oceanspray, rockspirea
  Homalobus caespitosus Nutt. -- not accepted
  Homalobus campestris Nutt. -- not accepted
  Hordeum pusillum Nutt. -- accepted -- little barley, little wildbarley
  Hordeum pusillum ssp. pusillum Nutt. -- not accepted -- little barley
  Hordeum pusillum var. pusillum Nutt. -- not accepted
  Horkelia fusca ssp. parviflora (Nutt. ex Hook. & Arn.) D.D. Keck -- not accepted -- smallflower horkelia
  Horkelia fusca var. parviflora (Nutt. ex Hook. & Arn.) Wawra -- accepted
  Horkelia parviflora Nutt. ex Hook. & Arn. -- not accepted
  Hosackia americana (Nutt.) Piper -- not accepted
  Hosackia maritima Nutt. -- not accepted
  Hosackia prostrata Nutt. -- not accepted
  Hosackia rubella Nutt. -- not accepted
  Hosackia strigosa Nutt. -- not accepted
  Houstonia longifolia var. tenuifolia (Nutt.) Alph. Wood -- not accepted -- longleaf summer bluet
  Houstonia purpurea var. tenuifolia (Nutt.) A. Gray -- not accepted
  Houstonia tenuifolia Nutt. -- not accepted
  Hudsonia ericoides ssp. montana (Nutt.) N.H. Nick. & J.E. Skog -- not accepted
  Hudsonia ericoides ssp. tomentosa (Nutt.) N.H. Nick. & J.E. Skog -- not accepted
  Hudsonia montana Nutt. -- accepted -- mountain golden heather, mountain goldenheather
  Hudsonia tomentosa Nutt. -- accepted -- hudsonie tomenteuse, sand golden-heather, sand-heather, woolly beachheather
  Hudsonia tomentosa var. tomentosa Nutt. -- not accepted -- woolly beachheather
  Humulus americanus Nutt. -- not accepted
  Humulus lupulus ssp. americanus (Nutt.) Á. Löve & D. Löve -- not accepted
  Hydrocharis cordifolia Nutt. -- not accepted
  Hydrolea ovata Nutt. ex Choisy -- accepted -- hairy hydrolea, ovate false fiddleleaf
  Hydrophyllum macrophyllum Nutt. -- accepted -- largeleaf waterleaf
  Hymenolobus Nutt. -- not accepted
  Hymenolobus procumbens (L.) Nutt. ex Schinz & Thell. -- not accepted
  Hymenopappus filifolius var. luteus (Nutt.) B.L. Turner -- accepted -- fineleaf hymenopappus
  Hymenopappus luteus Nutt. -- not accepted
  Hymenoxys glabra (Nutt.) Shinners -- not accepted
  Hymenoxys scaposa var. glabra (Nutt.) K.F. Parker -- not accepted
  Hymenoxys scaposa var. linearis (Nutt.) K.F. Parker -- not accepted
  Hymenoxys torreyana (Nutt.) K.F. Parker -- not accepted
  Hypopitys lanuginosa (Michx.) Nutt. -- not accepted
  Icacorea paniculata (Nutt.) Sudw. -- not accepted
  Iliamna acerifolia (Nutt. ex Torr. & A. Gray) Greene -- not accepted
  Ilysanthes grandiflora (Nutt.) Benth. -- not accepted
  Ilysanthes monticola (Nutt.) Raf. -- not accepted
  Impatiens fulva Nutt. -- not accepted
  Impatiens pallida Nutt. -- accepted -- pale snapweed, pale touch-me-not
  Indigofera leptosepala Nutt. ex Torr. & A. Gray -- not accepted
  Indigofera miniata var. leptosepala (Nutt. ex Torr. & A. Gray) B.L. Turner -- not accepted -- western indigo
  Inula alba Nutt. -- not accepted
  Inula divaricata Nutt. -- not accepted
  Ionactis alpina (Nutt.) Greene -- accepted -- crag aster, lava aster
  Ipomopsis congesta ssp. crebrifolia (Nutt.) A.G. Day -- accepted -- ballhead gilia, ballhead ipomopsis
  Ipomopsis crebrifolia (Nutt.) Dorn -- not accepted
  Ipomopsis multiflora (Nutt.) V.E. Grant -- accepted -- many-flower gilia, manyflowered gilia, manyflowered ipomopsis
  Ipomopsis pumila (Nutt.) V.E. Grant -- accepted -- dwarf gilia, dwarf ipomopsis, low skyrocket, spotted gilia
  Ipomopsis spicata (Nutt.) V.E. Grant -- accepted -- spiked gilia, spiked ipomopsis
  Ipomopsis spicata ssp. spicata (Nutt.) V.E. Grant -- accepted -- spiked ipomopsis
  Iris cristata ssp. lacustris (Nutt.) Iltis -- not accepted
  Iris cristata var. lacustris (Nutt.) Dykes -- not accepted
  Iris lacustris Nutt. -- accepted -- dwarf lake iris
  Iris missouriensis Nutt. -- accepted -- Rocky Mountain iris, western blue flag, wild iris, wildiris
  Isocoma Nutt. -- accepted -- goldenbush, isocoma, jimmyweed
  Isocoma menziesii var. vernonioides (Nutt.) G.L. Nesom -- accepted -- Menzies' goldenbush
  Isocoma veneta var. vernonioides (Nutt.) Jeps. -- not accepted
  Isocoma vernonioides Nutt. -- not accepted
  Isomeris Nutt. -- not accepted
  Isomeris arborea Nutt. -- not accepted
  Isopappus divaricatus (Nutt.) Torr. & A. Gray -- not accepted
  Iva acerosa (Nutt.) R.C. Jacks. -- not accepted -- copperweed
  Iva angustifolia Nutt. ex DC. -- accepted -- narrowleaf marsh elder, narrowleaf marshelder, narrowleaf sumpweed, Texas marsh elder
  Iva microcephala Nutt. -- accepted -- piedmont marsh elder, piedmont marshelder
  Iva xanthifolia Nutt. -- not accepted -- burweed marshelder, carelessweed, false ragweed, giant marshelder, giant sumpweed, horseweed, marshelder, rag sumpweed
  Iva xanthiifolia Nutt. -- not accepted -- burweed marshelder, carelessweed, false ragweed, giant marshelder, giant sumpweed, horseweed, marshelder, rag sumpweed
  Juniperus repens Nutt. -- not accepted
  Jussiaea leptocarpa Nutt. -- not accepted
  Kentrophyta montana Nutt. -- not accepted
  Kneiffia linifolia (Nutt.) Spach -- not accepted
  Kneiffia riparia (Nutt.) Small -- not accepted
  Koeleria arkansana Nutt. ex Scribn. -- not accepted
  Koeleria gracilis ssp. nitida (Nutt.) Domin -- not accepted
  Koeleria gracilis var. longifolia Nutt. ex Domin -- not accepted
  Koeleria longifolia Nutt. ex Domin -- not accepted
  Koeleria nitida Nutt. -- not accepted
  Koeleria nitida var. nitida Nutt. -- not accepted
  Koeleria oregana Nutt. ex Domin -- not accepted
  Koeleria paniculata Nutt. -- not accepted
  Koellia nuda (Nutt.) Kuntze -- not accepted
  Koellia pilosa (Nutt.) Britton -- not accepted
  Krigia amplexicaulis (Michx.) Nutt. -- not accepted
  Krigia dandelion (L.) Nutt. -- accepted -- potato dwarfdandelion, tuber dandelion, tuber dwarfdandelion
  Krigia montana (Michx.) Nutt. -- accepted -- mountain dwarfdandelion
  Krigia occidentalis Nutt. -- accepted -- western dwarfdandelion
  Lacinaria tenuifolia (Nutt.) Kuntze -- not accepted
  Lactuca hirsuta Muhl. ex Nutt. -- accepted -- hairy lettuce
  Lactuca hirsuta var. hirsuta Muhl. ex Nutt. -- not accepted -- hairy lettuce
  Lactuca ludoviciana (Nutt.) Riddell -- accepted -- biannual lettuce, Louisiana lettuce, wild lettuce
  Lactuca oblongifolia Nutt. -- not accepted
  Lactuca tatarica var. heterophylla (Nutt.) B. Boivin -- not accepted
  Lagophylla Nutt. -- accepted -- hareleaf
  Lagophylla ramosissima Nutt. -- accepted -- branched lagophylla, common hareleaf
  Lagophylla ramosissima ssp. ramosissima Nutt. -- not accepted -- branched hareleaf, branched lagophylla
  Larix occidentalis Nutt. -- accepted -- hackmatack, Montana larch, mountain larch, western larch, western tamarack
  Lasallea adnata (Nutt.) Semple & L. Brouillet -- not accepted
  Lasallea oblongifolia (Nutt.) Semple & L. Brouillet -- not accepted
  Lasallea X amethystina (Nutt.) Semple & L. Brouillet -- not accepted
  Lasthenia coronaria (Nutt.) Ornduff -- accepted -- royal goldfields
  Lathyrus linearis Nutt. -- not accepted
  Lathyrus littoralis (Nutt.) Endl. ex Walp. -- accepted -- Gray beach pea, silky beach pea
  Lathyrus ornatus Nutt. -- not accepted
  Lathyrus polymorphus Nutt. -- accepted -- manystem pea, manystem peavine
  Lathyrus polymorphus ssp. polymorphus Nutt. -- not accepted -- manystem pea, manystem peavine
  Lathyrus polymorphus ssp. polymorphus var. polymorphus Nutt. -- not accepted -- manystem pea, manystem peavine
  Lathyrus polymorphus var. polymorphus Nutt. -- accepted -- manystem pea
  Lathyrus polyphyllus Nutt. -- accepted -- leafy pea, Oregon pea
  Lathyrus strictus Nutt. -- not accepted
  Lathyrus vestitus Nutt. -- accepted -- Pacific pea
  Lathyrus vestitus ssp. vestitus Nutt. -- not accepted -- Pacific pea
  Lathyrus vestitus var. vestitus Nutt. -- accepted -- Pacific pea, wild pea
  Laurus albida Nutt. -- not accepted
  Laurus albidus Nutt. -- not accepted
  Lavauxia triloba (Nutt.) Spach -- not accepted
  Layia carnosa (Nutt.) Torr. & A. Gray -- accepted -- beach layia, beach tidytips
  Ledum glandulosum Nutt. -- not accepted -- glandular Labrador tea, western Labrador tea
  Ledum glandulosum var. glandulosum Nutt. -- not accepted
  Ledum groenlandicum ssp. glandulosum (Nutt.) A. Löve & D. Löve -- not accepted
  Lepachys columnifera (Nutt.) J.F. Macbr. -- not accepted
  Lepidanthus suaveolens (Pursh) Nutt. -- not accepted
  Lepidium campestre var. integrifolium (Nutt.) C.L. Hitchc. -- not accepted
  Lepidium integrifolium Nutt. -- accepted -- thickleaf pepperweed, thickleaf pepperwort
  Lepidium integrifolium var. integrifolium Nutt. -- not accepted -- thickleaf pepperweed
  Lepidium lasiocarpum Nutt. -- accepted -- hairypod pepperweed, shaggyfruit pepperweed
  Lepidium lasiocarpum ssp. lasiocarpum Nutt. -- accepted -- shaggyfruit pepperweed
  Lepidium lasiocarpum var. lasiocarpum Nutt. -- not accepted -- hairy-pod pepperwort, hairypod pepperweed, shaggyfruit pepperweed
  Lepidium montanum Nutt. -- accepted -- Montana pepperweed, mountain pepperweed, mountain pepperwort
  Lepidium montanum var. integrifolium (Nutt.) C.L. Hitchc. -- not accepted
  Lepidium montanum var. montanum Nutt. -- not accepted -- mountain pepperweed
  Lepidium nitidum Nutt. -- accepted -- shining pepperweed
  Lepidium nitidum var. nitidum Nutt. -- not accepted -- shining pepperweed
  Lepidotheca suaveolens (Pursh) Nutt. -- not accepted
  Leptandra virginica (L.) Nutt. -- not accepted
  Leptilon pusillum (Nutt.) Britton -- not accepted
  Leptochloa attenuata (Nutt.) Steud. -- not accepted
  Leptochloa filiformis f. attenuata (Nutt.) F.C. Gates -- not accepted
  Leptochloa filiformis var. attenuata (Nutt.) Steyerm. & Kucera -- not accepted
  Leptodactylon caespitosum Nutt. -- not accepted -- mat prickly gilia, mat prickly phlox
  Leptodactylon pungens (Torr.) Torr. ex Nutt. -- not accepted -- common prickly gilia, granite gilia, granite prickly gilia, granite prickly phlox
  Leptodactylon pungens var. pungens (Torr.) Torr. ex Nutt. -- not accepted
  Leptoseris sonchoides Nutt. -- not accepted
  Leptosiphon aureus (Nutt.) J.M. Porter & L.A. Johnson -- accepted -- golden linanthus
  Leptosiphon aureus ssp. aureus (Nutt.) J.M. Porter & L.A. Johnson -- accepted -- golden linanthus
  Leptosiphon bicolor Nutt. -- accepted -- true babystars
  Leptosyne californica Nutt. -- not accepted
  Leptotaenia californica Nutt. -- not accepted
  Leptotaenia dissecta Nutt. -- not accepted
  Leptotaenia multifida Nutt. -- not accepted
  Lepturus paniculatus Nutt. -- not accepted
  Lespedeza stuevei Nutt. -- accepted -- Stueve's lespedeza, tall lespedeza
  Lesquerella alpina (Nutt.) S. Watson -- not accepted -- alkaline bladderpod, alpine bladderpod
  Lesquerella alpina var. alpina (Nutt.) S. Watson -- not accepted -- alpine bladderpod
  Lesquerella angustifolia (Nutt. ex Torr. & A. Gray) S. Watson -- not accepted -- annual bladderpod, thread-leaved bladderpod, threadleaf bladderpod
  Lesquerella gracilis var. repanda (Nutt.) Payson -- not accepted
  Lesquerella ludoviciana (Nutt.) S. Watson -- not accepted -- foothill bladderpod, Louisiana bladderpod, silver bladderpod
  Lesquerella repanda (Nutt.) S. Watson -- not accepted
  Leucocrinum Nutt. ex A. Gray -- accepted -- starlily
  Leucocrinum montanum Nutt. ex A. Gray -- accepted -- common starlily, star-lily
  Leucospora Nutt. -- accepted
  Leucospora multifida (Michx.) Nutt. -- accepted -- narrowleaf paleseed
  Liatris borealis Nutt. -- not accepted
  Liatris graminifolia var. virgata (Nutt.) Fernald -- not accepted
  Liatris laevigata (Nutt.) Small -- accepted -- shortleaf blazing star
  Liatris spicata var. resinosa (Nutt.) Gaiser -- accepted -- dense blazing star
  Liatris tenuifolia Nutt. -- accepted -- shortleaf blazing star
  Liatris tenuifolia var. laevigata (Nutt.) B.L. Rob. -- not accepted
  Liatris tenuifolia var. tenuifolia Nutt. -- accepted -- shortleaf blazing star
  Liatris virgata Nutt. -- accepted -- dense blazing star, grassleaf gayfeather, wand blazing star
  Ligusticum apiifolium (Nutt. ex Torr. & A. Gray) A. Gray -- accepted -- celeryleaf licorice-root
  Lilium andinum Nutt. -- not accepted
  Lilium philadelphicum var. andinum (Nutt.) Ker Gawl. -- not accepted -- wood lily
  Limnalsine diffusa (Nutt.) Rydb. -- not accepted
  Limnas arkansana (Nutt.) Trin. ex Steud. -- not accepted
  Limnetis glabra Nutt. -- not accepted
  Limnodea arkansana (Nutt.) L.H. Dewey -- accepted -- Ozark grass, Ozarkgrass
  Limnodea arkansana var. arkansana (Nutt.) L.H. Dewey -- not accepted
  Linanthus aureus (Nutt.) Greene -- not accepted -- desert gold, golden desert-trumpets, golden deserttrumpets, golden linanthus
  Linanthus aureus ssp. aureus (Nutt.) Greene -- not accepted -- golden deserttrumpets, golden linanthus
  Linanthus bicolor (Nutt.) Greene -- not accepted -- true babystars
  Linanthus bicolor ssp. bicolor (Nutt.) Greene -- not accepted -- true babystars
  Linanthus caespitosus (Nutt.) J.M. Porter & L.A. Johnson -- accepted -- mat prickly phlox, matted prickly-phlox
  Lindernia grandiflora Nutt. -- accepted -- savannah false pimpernel
  Lindernia monticola Nutt. -- accepted -- piedmont false pimpernel
  Lipochaeta integrifolia (Nutt.) A. Gray -- not accepted -- Kure Atoll nehe
  Lipochaeta lanceolata Nutt. -- not accepted
  Lipochaeta micrantha (Nutt.) A. Gray -- not accepted -- Kauai nehe, nehe
  Lipochaeta micrantha var. micrantha (Nutt.) A. Gray -- not accepted -- Kauai nehe
  Listera convallarioides (Sw.) Nutt. ex Elliott -- not accepted -- broad-lip twayblade, broadleaf twayblade, broadlipped listera, broadlipped twayblade
  Lithococca tenella (Nutt.) Small -- not accepted
  Lithophragma (Nutt.) Torr. & A. Gray -- accepted -- woodland-star
  Lithophragma glabrum Nutt. -- accepted -- bulbous woodland-star, smooth woodland-star
  Lithophragma parviflorum (Hook.) Nutt. -- accepted -- smallflower woodland-star
  Lithophragma parviflorum var. parviflorum (Hook.) Nutt. -- not accepted -- smallflower woodland-star
  Lithophragma tenellum Nutt. -- accepted -- slender woodland-star
  Lithospermum pilosum Nutt. -- not accepted
  Lobelia aphylla Nutt. -- not accepted
  Lobelia brevifolia Nutt. ex A. DC. -- accepted -- shortleaf lobelia
  Lobelia paludosa Nutt. -- accepted -- white lobelia
  Loeflingia squarrosa Nutt. -- accepted -- California loeflingia, spreading pygmyleaf
  Loeflingia squarrosa ssp. squarrosa Nutt. -- not accepted -- spreading pygmyleaf, Texas loeflingia
  Loeflingia squarrosa var. squarrosa Nutt. -- not accepted
  Logfia californica (Nutt.) Holub -- not accepted
  Lomatium ambiguum (Nutt.) J.M. Coult. & Rose -- accepted -- Wyeth biscuitroot
  Lomatium ambiquum (Nutt.) J.M. Coult. & Rose -- not accepted
  Lomatium californicum (Nutt.) Mathias & Constance -- accepted -- California lomatium
  Lomatium dissectum (Nutt.) Mathias & Constance -- accepted -- chocolate-tips, desert parsley, fernleaf biscuitroot
  Lomatium dissectum var. dissectum (Nutt.) Mathias & Constance -- accepted -- fernleaf biscuitroot
  Lomatium dissectum var. multifidum (Nutt.) Mathias & Constance -- accepted -- carrotleaf biscuitroot
  Lomatium divaricatum (Pursh) Nutt. ex Torr. & A. Gray -- not accepted
  Lomatium foeniculaceum (Nutt.) J.M. Coult. & Rose -- accepted -- biscuitroot, carrot-leaf desert-parsley, desert biscuitroot
  Lomatium foeniculaceum ssp. foeniculaceum (Nutt.) J.M. Coult. & Rose -- accepted -- carrot-leaf desert-parsley, desert biscuitroot
  Lomatium laevigatum (Nutt.) J.M. Coult. & Rose -- accepted -- Slickrock biscuitroot
  Lomatium lucidum (Nutt. ex Torr. & A. Gray) Jeps. -- accepted -- shiny biscuitroot
  Lomatium macrocarpum (Nutt. ex Torr. & A. Gray) J.M. Coult. & Rose -- accepted -- bigseed biscuitroot, bigseed lomatium, large-fruit desert-parsley, largefruit biscuitroot, long mamma
  Lomatium simplex (Nutt.) J.F. Macbr. -- accepted -- Great Basin biscuitroot, Great Basin desertparsley, narrowleaf lomatium
  Lomatium simplex var. simplex (Nutt.) J.F. Macbr. -- accepted -- Great Basin biscuitroot, Great Basin desertparsley
  Lomatium tenuifolium Nutt. ex Torr. & A. Gray -- not accepted
  Lomatium utriculatum (Nutt. ex Torr. & A. Gray) J.M. Coult. & Rose -- accepted -- common lomatium
  Lotus americanus (Nutt.) Bisch. -- not accepted
  Lotus purshianus var. glaber (Nutt.) Munz -- not accepted
  Lotus rubellus (Nutt.) Greene -- not accepted
  Lotus scoparius (Nutt.) Ottley -- not accepted -- common deerweed
  Lotus scoparius var. scoparius (Nutt.) Ottley -- not accepted -- common deerweed
  Lotus strigosus (Nutt.) Greene -- not accepted -- Bishop's lotus, strigose bird's-foot trefoil, strigose bird's-foot-trefoil
  Lotus strigosus var. strigosus (Nutt.) Greene -- not accepted -- strigose bird's-foot trefoil, strigose deervetch
  Ludwigia leptocarpa (Nutt.) H. Hara -- accepted -- anglestem primrose-willow, anglestem waterprimrose
  Luetkea caespitosa (Nutt.) Britton -- not accepted
  Lupinus argenteus ssp. parviflorus (Nutt. ex Hook. & Arn.) L.Ll. Phillips -- not accepted
  Lupinus argenteus var. holosericeus (Nutt.) Barneby -- not accepted -- holo lupine
  Lupinus argenteus var. parviflorus (Nutt. ex Hook. & Arn.) C.L. Hitchc. -- not accepted
  Lupinus caespitosus Nutt. -- accepted -- dwarf lupine, stemless dwarf lupine
  Lupinus caespitosus var. caespitosus Nutt. -- accepted -- stemless dwarf lupine
  Lupinus diffusus Nutt. -- accepted -- Oak Ridge lupine
  Lupinus falcifer Nutt. ex Torr. & A. Gray (pro. syn.) -- not accepted
  Lupinus foliosus (Torr. & A. Gray) Nutt. ex Hook. -- not accepted
  Lupinus foliosus var. stenophyllus Nutt. -- not accepted
  Lupinus gracilis Nutt. -- not accepted
  Lupinus holosericeus Nutt. -- accepted -- holo lupine, Nuttall's lupine
  Lupinus lepidus ssp. caespitosus (Nutt.) Detling -- not accepted
  Lupinus parviflorus Nutt. ex Hook. & Arn. -- accepted -- lodgepole lupine
  Lupinus parviflorus ssp. parviflorus Nutt. ex Hook. & Arn. -- accepted -- lodgepole lupine
  Lupinus stenophyllus (Nutt.) Rydb. -- not accepted
  Lupinus truncatus Nutt. ex Hook. & Arn. -- accepted -- collared annual lupine
  Lupinus villosus ssp. diffusus (Nutt.) L.Ll. Phillips -- not accepted
  Lupinus villosus var. diffusus (Nutt.) Torr. & A. Gray -- not accepted
  Lycium californicum Nutt. ex A. Gray -- accepted -- California desert-thorn, California wolfberry
  Lycium californicum var. californicum Nutt. ex A. Gray -- accepted -- California desert-thorn
  Lycurus setosus (Nutt.) C. Reeder -- not accepted -- bristly wolfstail
  Lygodesma aphylla (Nutt.) D.C. -- not accepted
  Lygodesma grandiflora (Nutt.) Torr. & A. Gray -- not accepted
  Lygodesmia aphylla (Nutt.) DC. -- accepted -- rose rush
  Lygodesmia grandiflora (Nutt.) Torr. & A. Gray -- accepted -- largeflower skeletonplant, largeflower skeletonweed, rush-pink
  Lygodesmia grandiflora var. grandiflora (Nutt.) Torr. & A. Gray -- accepted
  Lygodesmia spinosa Nutt. -- not accepted
  Lyonia Nutt. -- accepted -- lyonias, staggerbush
  Lyonia ferruginea (Walter) Nutt. -- accepted -- crooked-wood, dragon-wood, rusty staggerbush, tree lyonia
  Machaeranthera canescens ssp. canescens var. sessiliflora (Nutt.) B.L. Turner -- not accepted -- hoary tansyaster
  Machaeranthera canescens var. sessiliflora (Nutt.) B.L. Turner -- not accepted -- hoary tansyaster
  Machaeranthera canescens var. viscosa (Nutt.) Piper -- not accepted
  Machaeranthera coronopifolia (Nutt.) A. Nelson -- not accepted
  Machaeranthera divaricata (Nutt.) Greene -- not accepted
  Machaeranthera glabriuscula (Nutt.) Cronquist & D.D. Keck -- not accepted
  Machaeranthera glabriuscula var. villosa (Nutt.) Cronquist & D.D. Keck -- not accepted
  Machaeranthera gracilis (Nutt.) Shinners -- not accepted -- slender goldenweed
  Machaeranthera grindelioides (Nutt.) Shinners -- not accepted -- rayless aster, rayless tansy-aster, rayless tansyaster
  Machaeranthera grindelioides var. grindelioides (Nutt.) Shinners -- not accepted -- rayless aster, rayless tansy-aster, rayless tansyaster
  Machaeranthera pinnata (Nutt.) Shinners -- not accepted
  Machaeranthera pulverulenta (Nutt.) Greene -- not accepted
  Machaeranthera sessiliflora (Nutt.) Greene -- not accepted
  Machaeranthera viscosa (Nutt.) Greene -- not accepted
  Maclura Nutt. -- accepted
  Macranthera Nutt. ex Benth. -- accepted
  Macronema discoidea Nutt. -- not accepted
  Macronema suffruticosum Nutt. -- not accepted
  Macrorhynchus heterophyllus Nutt. -- not accepted
  Madia capitata Nutt. -- not accepted
  Madia dissitiflora (Nutt.) Torr. & A. Gray -- not accepted
  Madia madioides (Nutt.) Greene -- not accepted -- woodland madia
  Madia sativa ssp. capitata (Nutt.) Piper -- not accepted
  Mahonia Nutt. -- not accepted -- barberry, Oregon grape
  Mahonia aquifolium (Pursh) Nutt. -- not accepted -- hollyleaved barberry
  Mahonia nervosa (Pursh) Nutt. -- not accepted -- Cascade barberry
  Mahonia nervosa var. nervosa (Pursh) Nutt. -- not accepted -- Cascade Oregon grape
  Maianthemum amplexicaule (Nutt.) W.A. Weber -- not accepted
  Maianthemum racemosum ssp. amplexicaule (Nutt.) LaFrankie -- accepted -- feathery false lily of the valley, feathery false lily of the vally, western Solomon's seal, western Solomon's-seal
  Maianthemum racemosum var. amplexicaule (Nutt.) Dorn -- not accepted
  Malacothamnus fasciculatus (Nutt. ex Torr. & A. Gray) Greene -- accepted -- Mendocino bushmallow
  Malacothrix incana (Nutt.) Torr. & A. Gray -- accepted -- dunedelion
  Malacothrix saxatilis (Nutt.) Torr. & A. Gray -- accepted -- cliff desert dandelion, cliff desertdandelion
  Malacothrix saxatilis var. saxatilis (Nutt.) Torr. & A. Gray -- accepted -- cliff desertdandelion
  Malacothrix saxatilis var. tenuifolia (Nutt.) A. Gray -- accepted -- cliff desert dandelion, cliff desertdandelion
  Malacothrix sonchoides (Nutt.) Torr. & A. Gray -- accepted -- sowthistle desert dandelion, sowthistle desertdandelion, yellow-saucers
  Malacothrix tenuifolia (Nutt.) Torr. & A. Gray -- not accepted
  Malosma Nutt. ex Abrams -- accepted -- laurel sumac
  Malosma laurina (Nutt.) Nutt. ex Abrams -- accepted -- laurel sumac
  Malus fusca var. levipes (Nutt.) C.K. Schneid. -- not accepted
  Malva fasciculata Nutt. ex Torr. & A. Gray -- not accepted
  Malvastrum coccineum (Nutt.) A. Gray -- not accepted
  Malvastrum fasciculatum (Nutt. ex Torr. & A. Gray) Greene -- not accepted
  Mammillaria vivipara (Nutt.) Haw. -- not accepted
  Manisuris campestris (Nutt.) Hitchc. -- not accepted
  Manisuris rugosa (Nutt.) Kuntze -- not accepted
  Marshallia caespitosa Nutt. ex DC. -- accepted -- puffballs, seep marshallia
  Marshallia caespitosa var. caespitosa Nutt. ex DC. -- not accepted -- puffballs
  Meconella Nutt. -- accepted -- fairypoppy
  Meconella oregana Nutt. -- accepted -- white fairypoppy
  Meehania cordata (Nutt.) Britton -- accepted -- Meehan's mint
  Megastachya obtusa (Nutt.) Schult. -- not accepted
  Mehania cordata (Nutt.) Britton -- not accepted
  Meibomia laevigata (Nutt.) Kuntze -- not accepted
  Meibomia pauciflora (Nutt.) Kuntze -- not accepted
  Melandrium baldwinii (Nutt.) Rohrb. -- not accepted
  Melanthera integrifolia (Nutt.) W.L. Wagner & H. Rob. -- accepted -- Kure Atoll nehe
  Melanthera micrantha (Nutt.) W.L. Wagner & H. Rob. -- accepted
  Melanthera micrantha ssp. micrantha (Nutt.) W.L. Wagner & H. Rob. -- accepted -- Kauai nehe
  Melica nitens (Scribn.) Nutt. ex Piper -- accepted -- shining oniongrass, threeflower melic, threeflower melicgrass
  Melica nitens Nutt. ex Scribn. -- not accepted
  Melica panicoides Nutt. -- not accepted
  Melica poaeoides Nutt. -- not accepted
  Melica scabra Nutt. -- not accepted
  Mentzelia congesta Nutt. ex Torr. & A. Gray -- accepted -- united blazingstar, Ventana blazingstar
  Mentzelia congesta var. congesta Nutt. ex Torr. & A. Gray -- not accepted -- Ventana blazingstar
  Mentzelia floridana Nutt. ex Torr. & A. Gray -- accepted -- poorman's patch
  Mentzelia multiflora (Nutt.) A. Gray -- accepted -- Adonis blazingstar, Adonis stickleaf, desert blazingstar, manyflowered mentzelia
  Mentzelia multiflora var. multiflora (Nutt.) A. Gray -- accepted -- Adonis blazingstar, multiflower stickleaf
  Mentzelia oligosperma Nutt. ex Sims -- accepted -- chickenthief, chickthief
  Mentzelia pumila Nutt. ex Torr. & A. Gray -- accepted -- dwarf blazingstar, dwarf mentzelia, golden blazingstar
  Mentzelia pumila var. multiflora (Nutt.) Urb. & Gilg -- not accepted
  Mentzelia pumila var. pumila Nutt. ex Torr. & A. Gray -- accepted -- dwarf mentzelia, dwarf stickleaf, golden blazingstar
  Merathrepta sericea (Nutt.) A. Heller -- not accepted
  Meriolix serrulata (Nutt.) Walp. -- not accepted
  Mertensia oblongifolia (Nutt.) G. Don -- accepted -- languid-lady, oblongleaf bluebells
  Mertensia oblongifolia var. oblongifolia (Nutt.) G. Don -- not accepted -- sagebrush bluebells
  Mesadenia lanceolata (Nutt.) Raf. -- not accepted
  Mesadenia tuberosa (Nutt.) Britton -- not accepted
  Metastelma scoparium (Nutt.) Vail -- not accepted
  Micranthemum micranthemoides (Nutt.) Wettst. -- accepted -- Nuttall's micranthemum, Nuttall's mudflower
  Micropiper leptostachyon (Nutt.) Small -- not accepted
  Microseris heterocarpa (Nutt.) K.L. Chambers -- not accepted
  Microseris laciniata ssp. leptosepala (Nutt.) K.L. Chambers -- accepted -- cutleaf silverpuffs
  Microseris leptosepala (Nutt.) A. Gray -- not accepted
  Microseris linearifolia (Nutt.) Sch. Bip. -- not accepted
  Miegia gigantea (Walter) Nutt. -- not accepted
  Miegia pumila Nutt. -- not accepted
  Mikania scandens var. pubescens (Nutt.) Torr. & A. Gray -- not accepted
  Milium cuspidatum (Nutt.) Spreng. -- not accepted
  Mimulus dentatus Nutt. ex Benth. -- accepted -- coastal monkeyflower
  Mimulus glutinosus var. puniceus (Nutt.) A. Gray -- not accepted
  Mimulus leptanthus (Nutt.) A.L. Grant -- not accepted
  Mimulus longiflorus (Nutt.) A.L. Grant -- not accepted
  Mimulus longiflorus var. longiflorus (Nutt.) A.L. Grant -- not accepted
  Mimulus puniceus (Nutt.) Steud. -- not accepted
  Mimulus rivularis Nutt. -- not accepted
  Mimulus tenellus Nutt. ex A. Gray -- not accepted
  Minuartia pungens (Nutt.) Mattf. -- not accepted
  Mirabilis decumbens (Nutt.) Daniels -- not accepted
  Mitella caulescens Nutt. -- accepted -- creeping miterwort, slightstemmed miterwort
  Mitellastra caulescens (Nutt.) Howell -- not accepted
  Mnesithea rugosa (Nutt.) de Koning & Sosef -- accepted
  Moldavica parviflora (Nutt.) Britton -- not accepted
  Monarda aristata Nutt. -- not accepted
  Monarda pectinata Nutt. -- accepted -- horse mint, miners lettuce, plains beebalm, pony beebalm, spotted beebalm
  Monarda russeliana Nutt. ex Sims -- accepted -- redpurple beebalm, Russell's henbit
  Moneses reticulata Nutt. -- not accepted
  Moneses uniflora ssp. reticulata (Nutt.) Calder & Roy L. Taylor -- not accepted
  Moneses uniflora var. reticulata (Nutt.) S.F. Blake -- not accepted
  Monolopia lanceolata Nutt. -- accepted -- common monolopia
  Monroa squarrosa (Nutt.) Torr. -- not accepted -- false buffalo grass, false buffalograss
  Montia dichotoma (Nutt.) Howell -- accepted -- dwarf minerslettuce
  Montia diffusa (Nutt.) Greene -- accepted -- spreading minerslettuce
  Montia perfoliata ssp. glauca (Nutt. ex Torr. & A. Gray) Ferris -- not accepted
  Montiastrum dichotomum (Nutt.) Rydb. -- not accepted
  Muhlenbergia andina (Nutt.) Hitchc. -- accepted -- foxtail muhly
  Muhlenbergia brevifolia (Nutt.) M.E. Jones -- not accepted
  Muhlenbergia montana (Nutt.) Hitchc. -- accepted -- mountain muhly
  Muhlenbergia paniculata (Nutt.) Columbus -- accepted
  Muhlenbergia paniculata (Nutt.) P.M. Peterson -- not accepted
  Muhlenbergia purpurea Nutt. -- not accepted
  Mulgedium oblongifolium (Nutt.) Reveal -- accepted -- blue lettuce
  Munroa squarrosa (Nutt.) Torr. -- accepted
  Munroa squarrosa var. squarrosa (Nutt.) Torr. -- not accepted
  Musineon hookeri (Torr. & A. Gray) Nutt. -- not accepted
  Musineon tenuifolium (Nutt. ex Torr. & A. Gray) J.M. Coult. & Rose -- accepted -- slender wildparsley
  Musineon trachyspermum Nutt. -- not accepted
  Musineum divaricatum (Pursh) Nutt. ex Torr. & A. Gray -- not accepted
  Musineum tenuifolium Nutt. ex Torr. & A. Gray -- not accepted
  Myosotis verna Nutt. -- accepted -- spring forget-me-not
  Myriophyllum hippuroides Nutt. ex Torr. & A. Gray -- accepted -- western watermilfoil
  Myzorrhiza ludoviciana (Nutt.) Rydb. -- not accepted
  Myzorrhiza multiflora (Nutt.) Rydb. -- not accepted
  Nama ovata (Nutt. ex Choisy) Britton -- not accepted
  Nasturtium curvisiliqua (Hook.) Nutt. ex Torr. & A. Gray -- not accepted
  Nasturtium lyratum Nutt. -- not accepted
  Nasturtium sessiliflorum Nutt. -- not accepted
  Nasturtium sinuatum Nutt. -- not accepted
  Navarretia leucocephala ssp. minima (Nutt.) A.G. Day -- accepted -- least navarretia
  Navarretia minima Nutt. -- not accepted
  Nemacaulis Nutt. -- accepted -- cottonheads
  Nemacaulis denudata Nutt. -- accepted -- cottonheads, woollyheads
  Nemacaulis denudata var. denudata Nutt. -- accepted -- cottonheads
  Nemacladus Nutt. -- accepted -- threadplant
  Nemacladus ramosissimus Nutt. -- accepted -- smallflower threadplant
  Nemastylis Nutt. -- accepted -- nemastylis, pleatleaf
  Nemastylis coelestina (Bartram) Nutt. -- not accepted
  Nemastylis geminiflora Nutt. -- accepted -- prairie pleatleaf
  Nemastylus geminiflora Nutt. -- not accepted
  Nemophila Nutt. -- accepted -- baby blue eyes, blue-eyes
  Nemophila microcalyx (Nutt.) Fisch. & C.A. Mey. -- not accepted
  Nemophila phacelioides Nutt. -- accepted -- baby blue-eyes, largeflower baby blue eyes, largeflower nemophila
  Neoholmgrenia andina (Nutt.) W.L. Wagner & Hoch -- accepted
  Nuttallia multiflora (Nutt.) Greene -- not accepted
  Oenothera andina Nutt. -- not accepted
  Oenothera bistorta Nutt. ex Torr. & A. Gray -- not accepted
  Oenothera caespitosa Nutt. -- not accepted -- tufted evening primrose, tufted evening-primrose
  Oenothera caespitosa ssp. caespitosa Nutt. -- not accepted -- tufted evening primrose, tufted evening-primrose
  Oenothera caespitosa ssp. marginata (Nutt. ex Hook. & Arn.) Munz -- not accepted -- tufted evening primrose, tufted evening-primrose
  Oenothera caespitosa ssp. montana (Nutt.) Munz -- not accepted
  Oenothera caespitosa var. marginata (Nutt. ex Hook. & Arn.) Munz -- not accepted
  Oenothera caespitosa var. montana (Nutt.) Durand -- not accepted
  Oenothera californica (Nutt. ex Torr. & A. Gray) Greene -- not accepted -- California eveningprimrose
  Oenothera cespitosa Nutt. -- accepted -- tufted evening primrose, tufted eveningprimrose
  Oenothera cespitosa ssp. cespitosa Nutt. -- accepted -- tufted evening primrose, tufted eveningprimrose
  Oenothera cespitosa ssp. marginata (Nutt. ex Hook. & Arn.) Munz -- accepted -- tufted evening primrose, tufted eveningprimrose
  Oenothera cespitosa ssp. montana (Nutt.) Munz -- not accepted
  Oenothera cespitosa var. marginata (Nutt. ex Hook. & Arn.) Munz -- not accepted
  Oenothera cespitosa var. montana (Nutt.) Durand -- not accepted
  Oenothera cruciata Nutt. ex G. Don -- not accepted
  Oenothera glabella Nutt. -- not accepted
  Oenothera heterantha Nutt. -- not accepted
  Oenothera heterophylla var. rhombipetala (Nutt. ex Torr. & A. Gray) Fosberg -- not accepted
  Oenothera humifusa Nutt. -- accepted -- seabeach evening primrose, seabeach evening-primrose, seabeach eveningprimrose
  Oenothera linifolia Nutt. -- accepted -- threadleaf evening primrose, threadleaf evening-primrose, threadleaf sundrop
  Oenothera macarocarpa Nutt. -- not accepted
  Oenothera macrocarpa Nutt. -- accepted -- bigfruit evening primrose, bigfruit evening-primrose, bigfruit eveningprimrose, Ozark sundrop
  Oenothera macrocarpa ssp. macrocarpa Nutt. -- accepted -- bigfruit evening primrose, bigfruit evening-primrose, bigfruit eveningprimrose
  Oenothera ovata Nutt. ex Torr. & A. Gray -- not accepted
  Oenothera pallida ssp. trichocalyx (Nutt.) Munz & W.M. Klein -- accepted -- pale evening primrose, pale evening-primrose
  Oenothera pallida var. trichocalyx (Nutt.) Dorn -- not accepted
  Oenothera parvula Nutt. ex Torr. & A. Gray -- not accepted
  Oenothera rhombipetala Nutt. ex Torr. & A. Gray -- accepted -- fourpoint evening primrose, fourpoint evening-primrose, fourpoint eveningprimrose, greater four-point evening-primrose
  Oenothera rhombipetala auct. non Nutt. ex Torr. & A. Gray -- not accepted -- fourpoint eveningprimrose
  Oenothera riparia Nutt. -- accepted
  Oenothera serrulata Nutt. -- accepted
  Oenothera speciosa Nutt. -- accepted -- pinkladies, Showy evening primrose, showy eveningprimrose
  Oenothera tetragona var. riparia (Nutt.) Munz -- not accepted
  Oenothera trichocalyx Nutt. -- not accepted
  Oenothera triloba Nutt. -- accepted -- stemless evening primrose, stemless evening-primrose, stemless eveningprimrose
  Oglifa californica (Nutt.) Rydb. -- not accepted
  Oldenlandia purpurea var. tenuifolia (Nutt.) A. Gray ex Chapm. -- not accepted
  Oligoneuron album (Nutt.) G.L. Nesom -- not accepted -- prairie goldenrod
  Oligosporus campestris ssp. pacificus (Nutt.) W.A. Weber -- not accepted
  Oligosporus pacificus (Nutt.) Poljakov -- not accepted
  Oligosporus pedatifidus (Nutt.) Poljakov -- not accepted
  Oonopsis (Nutt.) Greene -- accepted -- false goldenweed
  Oonopsis multicaulis (Nutt.) Greene -- accepted -- branched false goldenweed
  Oplismenus parvifolius (Nutt.) Kunth -- not accepted
  Opuntia fragilis (Nutt.) Haw. -- accepted -- brittle cactus, brittle pricklypear, fragile cactus, jumping cactus, little pricklypear
  Opuntia fragilis var. fragilis (Nutt.) Haw. -- not accepted -- brittle pricklypear, pygmy pricklypear
  Opuntia pusilla (Haw.) Nutt. -- accepted -- cockspur pricklypear
  Opuntia rutila Nutt. -- not accepted
  Orbexilum onobrychis (Nutt.) Rydb. -- accepted -- French-grass
  Orbexilum simplex (Nutt. ex Torr. & A. Gray) Rydb. -- accepted -- simple scurfpea, singlestem leather-root
  Orbexilum virgatum (Nutt.) Rydb. -- accepted -- pineland leather-root
  Orobanche fasciculata Nutt. -- accepted -- clustered broom-rape, clustered broomrape, purple broomrape, tufted broomrape
  Orobanche ludoviciana Nutt. -- accepted -- Louisiana broom-rape, Louisiana broomrape
  Orobanche ludoviciana ssp. ludoviciana Nutt. -- accepted -- Louisiana broom-rape, Louisiana broomrape, sand broomrape
  Orobanche ludoviciana ssp. multiflora (Nutt.) T.S. Collins ex H.L. White & W.C. Holmes -- accepted -- Louisiana broomrape, manyflower broomrape, manyflowered broomrape
  Orobanche ludoviciana var. multiflora (Nutt.) Beck -- not accepted
  Orobanche multiflora Nutt. -- not accepted
  Orophaca caespitosa (Nutt.) Britton -- not accepted
  Orophaca sericea (Nutt.) Britton -- not accepted
  Orthocarpus Nutt. -- accepted -- owl's-clover, owlclover
  Orthocarpus luteus Nutt. -- accepted -- golden-tongue owl-clover, yellow owl's-clover, yellow owlclover
  Orthopogon hirtellum (L.) Nutt. -- not accepted
  Orthopogon parvifolium Nutt. -- not accepted
  Orthosia scoparia (Nutt.) Liede & Meve -- accepted -- leafless swallow-wort
  Oryzopsis cuspidata (Nutt.) Benth. ex Vasey -- not accepted
  Oryzopsis parviflora Nutt. -- not accepted
  Osmadenia Nutt. -- accepted -- osmadenia
  Osmadenia tenella Nutt. -- accepted -- false rosinweed
  Osmorhiza occidentalis (Nutt. ex Torr. & A. Gray) Torr. -- accepted -- sweetanise, western sweetroot
  Othake callosa (Nutt.) Bush -- not accepted
  Othake sphacelata (Nutt. ex Torr.) Rydb. -- not accepted
  Oxalis acetosella ssp. oregana (Nutt.) D. Löve -- not accepted
  Oxalis albicans ssp. pilosa (Nutt.) Eiten -- accepted -- radishroot woodsorrel
  Oxalis corniculata ssp. pilosa (Nutt.) Lourteig -- not accepted
  Oxalis corniculata var. pilosa (Nutt.) B.L. Turner -- not accepted
  Oxalis oregana Nutt. -- accepted -- redwood-sorrel
  Oxalis pilosa Nutt. -- not accepted
  Oxalis pumila Nutt. -- not accepted
  Oxalis wrightii var. pilosa (Nutt.) Wiegand -- not accepted
  Oxybaphus decumbens (Nutt.) Sweet -- not accepted
  Oxydenia Nutt. -- not accepted
  Oxydenia filiformis Nutt. ex B.D. Jacks. -- not accepted
  Oxydenia virgata Nutt. ex B.D. Jacks. -- not accepted
  Oxypolis rigidior var. ambigua (Nutt.) B.L. Rob. -- not accepted
  Oxypolis ternata (Nutt.) A. Heller -- not accepted -- piedmont cowbane
  Oxytenia Nutt. -- accepted
  Oxytenia acerosa Nutt. -- accepted -- copperweed
  Oxytheca Nutt. -- accepted
  Oxytheca dendroidea Nutt. -- accepted -- narrowleaf oxytheca
  Oxytheca dendroidea ssp. dendroidea Nutt. -- accepted -- narrowleaf oxytheca
  Oxytheca foliosa Nutt. -- not accepted
  Oxytheca glandulosa Nutt. -- not accepted
  Oxytropis borealis var. viscida (Nutt.) S.L. Welsh -- accepted -- sticky crazyweed, sticky pointloco, viscid locoweed
  Oxytropis lagopus Nutt. -- accepted -- haresfoot crazyweed, haresfoot locoweed
  Oxytropis lagopus var. lagopus Nutt. -- accepted -- haresfoot locoweed
  Oxytropis leucantha var. viscida (Nutt.) B. Boivin -- not accepted
  Oxytropis multiceps Nutt. -- accepted -- flowery pointloco, Nuttall's oxytrope
  Oxytropis nana Nutt. -- accepted -- Wyoming locoweed
  Oxytropis nana var. nana Nutt. -- not accepted -- Wyoming locoweed
  Oxytropis sericea Nutt. -- accepted -- locoweed, silky crazyweed, silvery oxytrope, white crazyweed, white locoweed, white pointloco
  Oxytropis sericea var. sericea Nutt. -- accepted -- silvery oxytrope, white locoweed
  Oxytropis viscida Nutt. -- not accepted
  Oxytropis viscida var. viscida Nutt. -- not accepted -- oxytropis visqueux variété visqueux, sticky locoweed
  Pachylophis caespitosus (Nutt.) Raim. -- not accepted
  Pachylophis cespitosus (Nutt.) Raim. -- not accepted
  Pachylophis montanus (Nutt.) A. Nelson -- not accepted
  Packera cymbalarioides (Nutt.) W.A. Weber & Á. Löve -- not accepted -- cleftleaf groundsel
  Packera debilis (Nutt.) W.A. Weber & Á. Löve -- accepted -- weak groundsel
  Packera plattensis (Nutt.) W.A. Weber & Á. Löve -- accepted -- prairie groundsel
  Packera schweinitziana (Nutt.) W.A. Weber & Á. Löve -- accepted -- Schweinitz's ragwort
  Paeonia brownii ssp. californica (Nutt.) Abrams -- not accepted
  Paeonia californica Nutt. -- accepted -- California peony
  Palafoxia callosa (Nutt.) Torr. & A. Gray -- accepted -- small palafox, small palafoxia
  Palafoxia integrifolia (Nutt.) Torr. & A. Gray -- accepted -- coastal plain palafox, coastalplain palafox
  Palafoxia sphacelata (Nutt. ex Torr.) Cory -- accepted -- othake, rayed palafoxia
  Panicularia distans var. airoides (Nutt.) Scribn. -- not accepted
  Panicum baldwinii Nutt. ex Scribn. -- not accepted
  Panicum baldwinii Nutt. ex Kearney -- not accepted
  Panicum baldwinii Nutt. ex Chapm. -- not accepted
  Parietaria floridana Nutt. -- accepted -- Florida pellitory, pellitory
  Paronychia americana (Nutt.) Fenzl ex Walp. -- accepted -- American nailwort
  Paronychia americana ssp. americana (Nutt.) Fenzl ex Walp. -- not accepted -- American nailwort
  Paronychia argyrocoma (Michx.) Nutt. -- accepted -- silvery nailwort
  Paronychia depressa (Torr. & A. Gray) Nutt. ex A. Nelson -- accepted -- spreading nailwort
  Paronychia depressa var. depressa (Torr. & A. Gray) Nutt. ex A. Nelson -- not accepted -- spreading nailwort
  Paronychia herniarioides (Michx.) Nutt. -- accepted -- coastal plain nailwort, coastalplain nailwort
  Paronychia sessiliflora Nutt. -- accepted -- creeping nailwort, low nailwort, nailwort, stemless nailwort
  Parosela aurea (Nutt. ex Fraser) Britton -- not accepted
  Parosela enneandra (Nutt. ex Fraser) Britton -- not accepted
  Parthenium alpinum (Nutt.) Torr. & A. Gray -- accepted -- alpine feverfew, Arkansas River feverfew
  Paspalum racemosum Nutt. -- not accepted
  Paspalum racemulosum Nutt. -- not accepted
  Pedicularis pallida Nutt. -- not accepted
  Pediomelum digitatum (Nutt. ex Torr. & A. Gray) Isely -- accepted -- palmleaf Indian breadroot
  Pediomelum hypogaeum (Nutt.) Rydb. -- accepted -- scurfpea, subterranean Indian breadroot
  Pediomelum hypogaeum var. hypogaeum (Nutt.) Rydb. -- accepted -- subterranean Indian breadroot
  Peniophyllum linifolium (Nutt.) Pennell -- not accepted
  Pennisetum corrugatum (Elliott) Nutt. -- not accepted
  Pennisetum laevigatum Nutt. -- not accepted
  Pennisetum pungens Nutt. -- not accepted
  Penstemon albidus Nutt. -- accepted -- white penstemon
  Penstemon angustifolius Nutt. ex Pursh -- accepted -- broad-beard beardtongue, broadbeard beardtongue, narrowleaf penstemon
  Penstemon angustifolius var. angustifolius Nutt. ex Pursh -- accepted -- broad-beard beardtongue, broadbeard beardtongue
  Penstemon caespitosus Nutt. ex A. Gray -- accepted -- mat penstemon
  Penstemon caespitosus var. caespitosus Nutt. ex A. Gray -- accepted -- mat penstemon
  Penstemon cobaea Nutt. -- accepted -- cobaea beardtongue, cobaea penstemon
  Penstemon cobaea var. cobaea Nutt. -- accepted -- cobaea beardtongue
  Penstemon digitalis Nutt. ex Sims -- accepted -- talus slope penstemon
  Penstemon gracilis Nutt. -- accepted -- lilac penstemon, slender beardtongue, slender penstemon
  Penstemon gracilis var. gracilis Nutt. -- not accepted -- lilac beardtongue, lilac penstemon
  Penstemon grandiflorus Nutt. -- accepted -- large beardtongue, largeflowered penstemon
  Penstemon humilis Nutt. ex A. Gray -- accepted -- low beardtongue, low penstemon
  Penstemon humilis ssp. humilis Nutt. ex A. Gray -- not accepted -- low beardtongue, low penstemon
  Penstemon humilis var. humilis Nutt. ex A. Gray -- accepted -- low beardtongue
  Penstemon laevigatus ssp. digitalis (Nutt. ex Sims) R.W. Benn. -- not accepted
  Penstemon pumilus Nutt. -- accepted -- Salmon River beardtongue
  Penstemon tubiflorus Nutt. -- accepted -- white wand beardtongue
  Penstemon tubiflorus var. tubiflorus Nutt. -- not accepted -- white wand beardtongue
  Pentachaeta Nutt. -- accepted -- pygmydaisy
  Pentachaeta aurea Nutt. -- accepted -- golden chaetopappa
  Pentameris sericea (Nutt.) A. Nelson & J.F. Macbr. -- not accepted
  Peperomia leptostachya (Nutt.) Chapm. -- not accepted -- aridland peperomia
  Peplis diandra Nutt. ex DC. -- not accepted
  Peraphyllum Nutt. -- accepted
  Peraphyllum ramosissimum Nutt. -- accepted -- squaw apple, squawapple, wild crab apple
  Perideridia americana (Nutt. ex DC.) Rchb. -- accepted -- eastern yampah, Osage perideridia
  Peritoma arborea (Nutt.) Iltis -- accepted -- bladderpod spiderflower
  Peritoma arborea var. arborea (Nutt.) Iltis -- accepted -- bladderpod spiderflower
  Petalostemon decumbens Nutt. -- not accepted
  Petalostemon gracilis Nutt. -- not accepted
  Petalostemon multiflorus Nutt. -- not accepted
  Petalostemon villosus Nutt. -- not accepted
  Petasites hookerianus (Nutt.) Rydb. -- not accepted
  Petasites speciosus (Nutt.) Piper -- not accepted
  Petradoria pumila (Nutt.) Greene -- accepted -- grassy rockgoldenrod, rock goldenrod
  Petradoria pumila ssp. pumila (Nutt.) Greene -- accepted -- grassy rock goldenrod, grassy rockgoldenrod
  Petrophyton caespitosum (Nutt.) Rydb. -- not accepted -- mat rockspirea, rockspirea, tufted rockmat
  Petrophyton caespitosum var. caespitosum (Nutt.) Rydb. -- not accepted -- mat rockspirea, Rocky Mountain rockmat, Rocky Mountain rockspirea
  Petrophytum (Nutt. ex Torr. & A. Gray) Rydb. -- accepted -- rockspirea
  Petrophytum caespitosum (Nutt.) Rydb. -- accepted -- mat rockspirea
  Petrophytum caespitosum ssp. caespitosum (Nutt.) Rydb. -- accepted -- rock spiraea
  Petrophytum caespitosum var. caespitosum (Nutt.) Rydb. -- not accepted -- mat rockspirea
  Peucedanum ambiguum (Nutt.) Nutt. ex Torr. & A. Gray -- not accepted
  Peucedanum macrocarpum Nutt. ex Torr. & A. Gray -- not accepted
  Phaca longifolia (Pursh) Nutt. -- not accepted
  Phacelia glabra Nutt. -- accepted -- smooth phacelia, smooth scorpionweed
  Phacelia glandulosa Nutt. -- accepted -- glandular phacelia
  Phacelia glandulosa var. glandulosa Nutt. -- accepted -- glandular phacelia
  Phacelia hirsuta Nutt. -- accepted -- fuzzy phacelia, hairy phacelia
  Phacelia ranunculacea (Nutt.) Constance -- accepted -- oceanblue phacelia
  Phalaris maritima Nutt. -- not accepted
  Phalaris occidentalis Nutt. -- not accepted
  Phaseolus polystachios var. sinuatus (Nutt. ex Torr. & A. Gray) R. Marechal, J.M. Mascherpa & F. Stainier -- accepted -- thicket bean
  Phaseolus sinuatus Nutt. ex Torr. & A. Gray -- not accepted
  Phellopterus montanus Nutt. ex Torr. & A. Gray (pro. syn.) -- not accepted
  Phemeranthus parviflorus (Nutt.) Kiger -- accepted -- sunbright
  Philadelphus hirsutus Nutt. -- accepted -- streambank mock orange
  Philadelphus hirsutus var. hirsutus Nutt. -- not accepted -- streambank mockorange
  Philadelphus oreganus Nutt. ex Torr. & A. Gray -- not accepted -- Oregon mock orange
  Phlox bryoides Nutt. -- not accepted
  Phlox caespitosa Nutt. -- accepted -- Douglas phlox, tufted phlox
  Phlox hentzii Nutt. -- not accepted
  Phlox hoodii ssp. muscoides (Nutt.) Wherry -- accepted -- moss phlox, musk phlox
  Phlox longifolia Nutt. -- accepted -- longleaf phlox
  Phlox longifolia ssp. longifolia Nutt. -- accepted -- longleaf phlox
  Phlox muscoides Nutt. -- not accepted
  Phlox nana Nutt. -- accepted -- Santa Fe phlox
  Phlox nivalis ssp. hentzii (Nutt.) Wherry -- accepted -- Hentz's phlox
  Phoenicaulis Nutt. -- accepted
  Phoenicaulis cheiranthoides Nutt. -- accepted -- wallflower phoenicaulis
  Phoenicaulis cheiranthoides var. cheiranthoides Nutt. -- not accepted
  Pholisma Nutt. ex Hook. -- accepted
  Pholisma arenarium Nutt. ex Hook. -- accepted -- desert Christmas tree
  Pholistoma racemosa (Nutt. ex A. Gray) Constance -- not accepted
  Pholistoma racemosum (Nutt. ex A. Gray) Constance -- accepted -- racemed fiestaflower
  Phoradendron Nutt. -- accepted -- mistletoe
  Phoradendron californicum Nutt. -- accepted -- mesquite mistletoe
  Phoradendron flavescens (Pursh) Nutt. ex A. Gray. -- not accepted
  Phoradendron flavescens var. villosum (Nutt.) Engelm. -- not accepted
  Phoradendron villosum (Nutt.) Nutt. ex Engelm. -- accepted -- Pacific mistletoe
  Phoradendron villosum ssp. villosum (Nutt.) Nutt. ex Engelm. -- not accepted -- Pacific mistletoe
  Phyllanthus polygonoides Nutt. ex Spreng. -- accepted -- knotweed leaflower, smartweed leaf-flower, smartweed leafflower
  Physalis angustifolia Nutt. -- accepted -- coastal groundcherry
  Physalis longifolia Nutt. -- accepted -- common groundcherry, long-leaf ground-cherry, longleaf groundcherry
  Physalis longifolia var. longifolia Nutt. -- accepted -- long-leaf ground-cherry, longleaf groundcherry
  Physalis mollis Nutt. -- accepted -- field groundcherry
  Physalis mollis var. mollis Nutt. -- accepted -- field groundcherry
  Physalis pumila Nutt. -- accepted -- dwarf groundcherry
  Physalis viscosa ssp. mollis (Nutt.) Waterf. -- not accepted
  Physalis walteri Nutt. -- accepted -- Walter's groundcherry
  Physaria (Nutt. ex Torr. & A. Gray) A. Gray -- accepted -- twinpod
  Physaria angustifolia (Nutt. ex Torr. & A. Gray) O'Kane & Al-Shehbaz -- accepted -- threadleaf bladderpod
  Physaria ludoviciana (Nutt.) O'Kane & Al-Shehbaz -- accepted -- foothill bladderpod
  Physostegia intermedia (Nutt.) Engelm. & A. Gray -- accepted -- intermediate dragonhead, slender false dragonhead
  Physostegia parviflora Nutt. ex A. Gray -- accepted -- false dragonhead, western false dragonhead
  Physostegia virginiana var. parviflora (Nutt. ex A. Gray) B. Boivin -- not accepted
  Pickeringia Nutt. -- accepted -- chaparral pea
  Pickeringia montana Nutt. -- accepted -- chaparral pea, Montana chaparral pea
  Pickeringia montana var. montana Nutt. -- accepted -- chaparral pea, Montana chaparral pea
  Picradeniopsis oppositifolia (Nutt.) Rydb. ex Britton -- accepted -- opposite-leaf false bahia, oppositeleaf bahia, plains bahia
  Picrothamnus Nutt. -- accepted -- bud sagebrush
  Picrothamnus desertorum Nutt. -- accepted -- bud sagebrush
  Pinus strobus var. monticola (Douglas ex D. Don) Nutt. -- not accepted
  Piper leptostachyon Nutt. -- not accepted
  Pitavia dumosa Nutt. -- not accepted
  Pitcheria Nutt. -- not accepted
  Pitcheria galactioides Nutt. -- not accepted
  Pitcheria galactoides Nutt. -- not accepted
  Pityopsis Nutt. -- accepted -- pityopsis, silkgrass
  Pityopsis falcata (Pursh) Nutt. -- accepted -- sickleleaf silkgrass
  Pityopsis graminifolia (Michx.) Nutt. -- accepted -- narrowleaf silkgrass
  Pityopsis graminifolia var. graminifolia (Michx.) Nutt. -- accepted -- narrowleaf silkgrass
  Pityopsis pinifolia (Elliot) Nutt. -- accepted -- Taylor County goldaster
  Plagiobothrys tenellus (Nutt. ex Hook.) A. Gray -- accepted -- Pacific popcornflower
  Plantago heterophylla Nutt. -- accepted -- slender plantain
  Plantago patagonica var. gnaphalioides (Nutt.) A. Gray -- not accepted
  Plantago pusilla Nutt. -- accepted -- dwarf plantain, woolly Indianwheat, woolly plantain
  Platanthera huronensis (Nutt.) Lindl. -- accepted -- Huron green orchid
  Platanthera hyperborea var. huronensis (Nutt.) Luer -- not accepted -- Huron green orchid
  Platanthera integra (Nutt.) A. Gray ex L.C. Beck -- not accepted -- yellow fringeless orchid
  Platanthera leucophaea (Nutt.) Lindl. -- accepted -- eastern prairie fringed orchid, prairie white fringed orchid
  Platanthera nivea (Nutt.) Luer -- not accepted -- snowy orchid
  Platanthera repens (Nutt.) Alph. Wood -- not accepted
  Platanus racemosa Nutt. -- accepted -- California sycamore
  Plectocephalus americanus (Nutt.) D. Don -- accepted -- American star-thistle
  Pleiacanthus spinosus (Nutt.) Rydb. -- accepted -- thorn skeletonweed
  Pleopogon Nutt. -- not accepted
  Pleopogon setosum Nutt. -- not accepted
  Pleopogon setosus Nutt. -- not accepted
  Pleuraphis sericea Nutt. ex Benth. -- not accepted
  Pluchea sericea (Nutt.) Coville -- accepted -- arrowweed
  Poa airoides Nutt. -- not accepted
  Poa andina Nutt. ex S. Watson -- not accepted
  Poa andina Nutt. ex Vasey -- not accepted
  Poa capitata Nutt. -- not accepted
  Poa cuspidata Nutt. -- accepted -- early bluegrass
  Poa interrupta Nutt. -- not accepted
  Poa melicoides (Michx.) Nutt. -- not accepted
  Poa obtusa Nutt. -- not accepted
  Poa parviflora Nutt. -- not accepted
  Poa pungens Nutt. -- not accepted
  Poa tenella Nutt. -- not accepted
  Poa tenuifolia Nutt. ex S. Watson -- not accepted
  Poa trichodes Nutt. -- not accepted
  Podostemum abrotanoides Nutt. -- not accepted
  Polanisia erosa (Nutt.) Iltis -- accepted -- large clammyweed
  Polanisia erosa ssp. erosa (Nutt.) Iltis -- accepted -- large clammyweed
  Polemonium viscosum Nutt. -- accepted -- sticky Jacob's-ladder, sticky polemonium
  Polemonium viscosum var. viscosum Nutt. -- not accepted
  Polyantherix hystrix (Nutt.) Nees -- not accepted
  Polycarpon depressum Nutt. -- accepted -- California manyseed
  Polycodium floridanum (Nutt.) Greene -- not accepted
  Polygala alba Nutt. -- accepted -- white milkwort
  Polygala ambigua Nutt. -- accepted -- whorled milkwort
  Polygala balduinii Nutt. -- accepted -- Baldwin's milkwort
  Polygala balduinii var. balduinii Nutt. -- not accepted -- Baldwin's milkwort
  Polygala boykinii Nutt. -- accepted -- Boykin's milkwort
  Polygala boykinii var. boykinii Nutt. -- accepted -- Boykin's milkwort
  Polygala brevifolia Nutt. -- accepted -- littleleaf milkwort
  Polygala californica Nutt. -- accepted -- California milkwort
  Polygala verticillata var. ambigua (Nutt.) Alph. Wood -- not accepted -- whorled milkwort
  Polygonum buxifolium Nutt. ex Bong. -- not accepted
  Polygonum confertiflorum Nutt. ex Piper -- not accepted
  Polygonum glaucum Nutt. -- accepted -- seaside knotweed
  Polygonum gracile Nutt. -- not accepted
  Polygonum imbricatum Nutt. -- not accepted
  Polygonum kelloggii var. confertiflorum (Nutt. ex Piper) Dorn -- not accepted
  Polygonum polygaloides ssp. confertiflorum (Nutt. ex Piper) J.C. Hickman -- accepted -- denseflower knotweed, fruitleaf knotweed
  Polyotus angustifolius Nutt. -- not accepted
  Polypappus sericeus Nutt. -- not accepted
  Polypogon crinitus (Schreb.) Nutt. -- not accepted
  Polypogon racemosus (Michx.) Nutt. -- not accepted
  Polypteris callosa (Nutt.) A. Gray -- not accepted
  Polypteris integrifolia Nutt. -- not accepted
  Polypteris sphacelata (Nutt. ex Torr.) Trel. -- not accepted
  Pontederia cordata var. lanceolata (Nutt.) Griseb. -- not accepted
  Pontederia lanceolata Nutt. -- not accepted
  Potentilla brevifolia Nutt. -- accepted -- sparseleaf cinquefoil
  Potentilla douglasii var. parviflora (Nutt. ex Hook. & Arn.) J.T. Howell -- not accepted -- pinewoods horkelia
  Potentilla effusa var. filicaulis Nutt. -- not accepted
  Potentilla effusa var. gossypina Nutt. ex Torr. & A. Gray -- not accepted
  Potentilla fastigiata Nutt. -- not accepted
  Potentilla fissa Nutt. -- not accepted -- bigflower cinquefoil
  Potentilla gracilis var. fastigiata (Nutt.) S. Watson -- accepted -- northwest cinquefoil, Nuttall's cinquefoil, slender cinquefoil
  Potentilla gracilis var. flabelliformis (Lehm.) Nutt. ex Torr. & A. Gray -- accepted -- fanleaf cinquefoil, slender cinquefoil
  Potentilla hippiana var. filicaulis (Nutt.) B. Boivin -- not accepted
  Potentilla paradoxa Nutt. -- not accepted -- bushy cinquefoil, Paradox cinquefoil
  Potentilla plattensis Nutt. -- accepted -- Platte cinquefoil, Platte River cinquefoil
  Potentilla rivalis Nutt. -- accepted -- brook cinquefoil, river cinquefoil
  Potentilla rivalis var. rivalis Nutt. -- not accepted -- brook cinquefoil
  Potentilla supina ssp. paradoxa (Nutt.) Soják -- accepted -- bushy cinquefoil
  Potentilla supina var. paradoxa (Nutt.) Th. Wolf -- not accepted
  Poteridium annuum (Nutt.) Spach -- accepted -- prairie burnet
  Poterium annuum Nutt. -- not accepted
  Prionopsis Nutt. -- not accepted -- prionopsis
  Prionopsis ciliata (Nutt.) Nutt. -- not accepted
  Prunus demissa (Nutt.) Walp. -- not accepted
  Prunus demissa (Nutt.) D. Dietr. -- not accepted
  Prunus ilicifolia (Nutt. ex Hook. & Arn.) D. Dietr. -- accepted -- hollyleaf cherry
  Prunus ilicifolia ssp. ilicifolia (Nutt. ex Hook. & Arn.) D. Dietr. -- not accepted -- hollyleaf cherry
  Prunus ilicifolia var. ilicifolia (Nutt. ex Hook. & Arn.) D. Dietr. -- accepted -- hollyleaf cherry
  Prunus virginiana ssp. demissa (Nutt.) Roy L. Taylor & MacBryde -- not accepted
  Prunus virginiana var. demissa (Nutt.) Torr. -- accepted -- western chokecherry
  Psathyrotes annua (Nutt.) A. Gray -- accepted -- annual psathyrotes, mealy rosettes, turtleback
  Pseudognaphalium canescens ssp. microcephalum (Nutt.) Kartesz -- not accepted -- Wright's cudweed
  Pseudognaphalium microcephalum (Nutt.) Anderb. -- accepted -- Wright's cudweed
  Pseudognaphalium ramosissimum (Nutt.) Anderb. -- accepted -- pink cudweed
  Psilocarphus Nutt. -- accepted -- woollyheads, woolyheads
  Psilocarphus brevissimus Nutt. -- accepted -- dwarf woolyheads, short woollyheads
  Psilocarphus brevissimus var. brevissimus Nutt. -- accepted -- short woollyheads
  Psilocarphus oregonus Nutt. -- accepted -- Oregon woollyheads
  Psilocarphus tenellus Nutt. -- accepted -- slender woollyheads
  Psilocarphus tenellus var. tenellus Nutt. -- not accepted -- slender woollyheads
  Psilochenia acuminata (Nutt.) W.A. Weber -- not accepted
  Psilochenia occidentalis (Nutt.) Nutt. -- not accepted
  Psilochenia runcinata ssp. glauca (Nutt.) W.A. Weber -- not accepted
  Psilostrophe tagetina (Nutt.) Greene -- accepted -- woolly paperflower, wooly paperflower
  Psilostrophe tagetina var. tagetina (Nutt.) Greene -- not accepted -- woolly paperflower, wooly paperflower
  Psoralea digitata Nutt. ex Torr. & A. Gray -- not accepted
  Psoralea floribunda Nutt. ex Torr. & A. Gray -- not accepted
  Psoralea hypogaea Nutt. -- not accepted
  Psoralea lanceolata ssp. scabra (Nutt.) Piper -- not accepted
  Psoralea onobrychis Nutt. -- not accepted
  Psoralea scabra Nutt. -- not accepted
  Psoralea simplex Nutt. ex Torr. & A. Gray -- not accepted
  Psoralea tenuiflora var. floribunda (Nutt. ex Torr. & A. Gray) Rydb. -- not accepted
  Psoralea virgata Nutt. -- not accepted
  Psoralidium digitatum (Nutt. ex Torr. & A. Gray) Rydb. -- not accepted
  Psychotria lanceolata Nutt. -- not accepted
  Psychotria nervosa var. lanceolata (Nutt.) Sarg. -- not accepted
  Pterophyton pauciflorum (Nutt.) Alexander -- not accepted
  Pterospora Nutt. -- accepted -- pinedrops
  Pterospora andromedea Nutt. -- accepted -- giant bird's nest, giant pinedrops, woodland pinedrops
  Pteryxia (Nutt. ex Torr. & A. Gray) Nutt. ex J.M. Coult. & Rose -- accepted -- springparsley, wavewing
  Pycnanthemum incanum var. loomisii (Nutt.) Fernald -- not accepted
  Pycnanthemum loomisii Nutt. -- accepted -- Loomis' mountainmint
  Pycnanthemum nudum Nutt. -- accepted -- coastal plain mountainmint, coastalplain mountainmint
  Pycnanthemum pilosum Nutt. -- accepted -- whorled mountainmint
  Pycnanthemum setosum Nutt. -- accepted -- awned mountainmint
  Pycnanthemum verticillatum var. pilosum (Nutt.) Cooperr. -- not accepted -- whorled mountainmint
  Pylostachya balduinii (Nutt.) Small -- not accepted
  Pyrola aphylla var. leptosepala Nutt. -- not accepted
  Pyrola elata Nutt. -- not accepted
  Pyrola elliptica Nutt. -- accepted -- elliptic shineleaf, large-leaved shineleaf, waxflower shinleaf
  Pyrrhopappus grandiflorus (Nutt.) Nutt. -- accepted -- tuberous desert-chicory, tuberous desertchicory
  Pyrrocoma racemosa (Nutt.) Torr. & A. Gray -- accepted -- clustered goldenweed
  Pyrrocoma racemosa var. paniculata (Nutt.) Kartesz & Gandhi -- accepted -- clustered goldenweed
  Pyrrocoma racemosa var. racemosa (Nutt.) Torr. & A. Gray -- accepted -- clustered goldenweed
  Pyrrocoma radiata Nutt. -- accepted -- ray goldenweed, Snake River goldenweed
  Pyrrocoma radiata var. radiata Nutt. -- not accepted
  Quercus dumosa Nutt. -- accepted -- coastal sage scrub oak, Nuttall's scrub oak
  Quercus dumosa var. dumosa Nutt. -- not accepted -- coastal sage scrub oak
  Quercus falcata var. triloba (Michx.) Nutt. -- not accepted
  Quercus gambelii Nutt. -- accepted -- Gambel's oak
  Quercus gambelii var. gambelii Nutt. -- not accepted -- Gambel's oak
  Quercus macrocarpa var. depressa (Nutt.) Engelm. -- not accepted -- bur oak
  Quercus michauxii Nutt. -- accepted -- swamp chestnut oak
  Quercus X leana Nutt. (pro sp.) -- accepted -- oak
  Radicula obtusa (Nutt.) Greene -- not accepted
  Radicula sessiliflora (Nutt.) Greene -- not accepted
  Radicula sinuata (Nutt.) Greene -- not accepted
  Rafinesquia Nutt. -- accepted -- California chicory, chicory, plumeseed
  Rafinesquia californica Nutt. -- accepted -- California chicory, California plumeseed
  Raimannia humifusa (Nutt.) Rose -- not accepted
  Raimannia rhombipetala (Nutt. ex Torr. & A. Gray) Rose -- not accepted
  Ranunculus bongardii var. tenellus (Nutt.) Greene -- not accepted
  Ranunculus gmelini var. limosus (Nutt.) H. Hara -- not accepted
  Ranunculus gmelinii var. limosus (Nutt.) H. Hara -- not accepted -- Gmelin's buttercup
  Ranunculus limosus Nutt. -- not accepted
  Ranunculus micranthus Nutt. -- accepted -- rock buttercup
  Ranunculus occidentalis Nutt. -- accepted -- western buttercup
  Ranunculus occidentalis var. occidentalis Nutt. -- accepted -- western buttercup
  Ranunculus raninculinus (Nutt.) Rydb. -- not accepted
  Ranunculus ranunculinus (Nutt.) Rydb. -- accepted -- tadpole buttercup
  Ranunculus sceleratus ssp. multifidus (Nutt.) Hultén -- not accepted
  Ranunculus sceleratus var. multifidus Nutt. -- accepted -- blister buttercup, cursed buttercup
  Ratibida columnifera (Nutt.) Woot. & Standl. -- accepted -- prairie coneflower, redspike Mexican hat, upright prairie coneflower
  Rhamnus crocea Nutt. -- accepted -- hollyleaf buckthorn, redberry buckthorn
  Rhamnus crocea ssp. crocea Nutt. -- accepted -- redberry buckthorn
  Rhexia serrulata Nutt. -- not accepted
  Rhus aromatica ssp. trilobata (Nutt.) W.A. Weber -- not accepted
  Rhus aromatica var. trilobata (Nutt.) A. Gray ex S. Watson -- not accepted -- ill-scented sumac, skunkbush sumac
  Rhus integrifolia (Nutt.) Benth. & Hook. f. ex W.H. Brewer & S. Watson -- accepted -- lemonade sumac
  Rhus laurina Nutt. -- not accepted
  Rhus trilobata Nutt. -- not accepted -- skunkbush sumac
  Rhus trilobata var. trilobata Nutt. -- not accepted -- ill-scented sumac, skunkbush, skunkbush sumac
  Rhynchosia galactoides (Nutt.) Endl. ex Walp. -- not accepted
  Rhynchosia latifolia Nutt. ex Torr. & A. Gray -- accepted -- broadleaf snoutbean, prairie snoutbean
  Ribes missouriense Nutt. -- accepted -- Missouri gooseberry
  Ribes reniforme Nutt. -- not accepted
  Ribes rotundifolium var. villosum (Nutt.) Dippel -- not accepted
  Ribes villosum Nutt. -- not accepted
  Riddellia tagetina (Nutt.) Greene -- not accepted
  Rorippa curvisiliqua var. lyrata (Nutt.) M. Peck ex C.L. Hitchc. -- not accepted -- lyrateleaf yellowcress
  Rorippa lyrata (Nutt.) Greene -- not accepted
  Rorippa obtusa (Nutt.) Britton -- not accepted
  Rorippa palustris var. cernua (Nutt.) Stuckey -- not accepted
  Rorippa sessiliflora (Nutt.) Hitchc. -- accepted -- stalkless yellowcress
  Rorippa sinuata (Nutt.) Hitchc. -- accepted -- spreading yellowcress
  Rosa foliolosa Nutt. ex Torr. & A. Gray -- accepted -- white prairie rose
  Rosa gymnocarpa Nutt. -- accepted -- dwarf rose
  Rosa gymnocarpa var. gymnocarpa Nutt. -- accepted -- dwarf rose, wood rose
  Rottboellia campestris Nutt. -- not accepted
  Rottboellia ciliata Nutt. -- not accepted
  Rottboellia paniculata (Nutt.) Spreng. -- not accepted
  Rottboellia rugosa Nutt. -- not accepted
  Rubacer parviflorum (Nutt.) Rydb. -- not accepted
  Rubacer parviflorus (Nutt.) Rydb. -- not accepted
  Rubus parviflorus Nutt. -- accepted -- thimbleberry, western thimbleberry
  Rubus parviflorus var. parviflorus Nutt. -- not accepted -- thimbleberry, western thimbleberry
  Rudbeckia bicolor Nutt. -- not accepted -- pinewoods coneflower
  Rudbeckia columnifera Nutt. -- not accepted
  Rudbeckia globosa Nutt. -- not accepted
  Rudbeckia hirta var. serotina (Nutt.) Core -- not accepted
  Rudbeckia maxima Nutt. -- accepted -- great coneflower
  Rudbeckia nitida Nutt. -- accepted -- shiny coneflower
  Rudbeckia nitida var. nitida Nutt. -- not accepted -- shiny coneflower
  Rudbeckia occidentalis Nutt. -- accepted -- western coneflower
  Rudbeckia occidentalis var. occidentalis Nutt. -- not accepted -- western coneflower
  Rudbeckia pallida Nutt. -- not accepted
  Rudbeckia serotina Nutt. -- not accepted
  Ruellia humilis Nutt. -- accepted -- fringeleaf wild petunia, low ruellia, wild petunia
  Ruellia humilis sensu Small, non Nutt. -- not accepted -- fringeleaf wild petunia
  Ruellia humilis var. humilis Nutt. -- not accepted -- fringeleaf wild petunia
  Rufacer drummondii (Hook. & Arn. ex Nutt.) Small -- not accepted
  Rumex paucifolius Nutt. -- accepted -- alpine sheep sorrel, fewleaved dock, meadow dock
  Rumex paucifolius ssp. paucifolius Nutt. -- not accepted -- alpine sheep sorrel, fewleaved dock
  Sabatia campestris Nutt. -- accepted -- meadow pink, prairie rose gentian, Texas star
  Sabulina brevifolia (Nutt. ex Torr. & A. Gray) Small -- not accepted
  Saccharodendron grandidentatum (Nutt.) Nieuwl. -- not accepted
  Saccharum alopecuroides (L.) Nutt. -- accepted
  Saccharum alopecuroidum (L.) Nutt. -- not accepted -- silver plumegrass
  Saccharum contortum (Elliott) Nutt. -- not accepted
  Saccharum strictum (Baldwin) Nutt. -- not accepted
  Sagittaria arifolia Nutt. ex J.G. Sm. -- not accepted
  Salix argophylla Nutt. -- not accepted
  Salix brachycarpa Nutt. -- accepted -- barrenground willow, shortfruit willow
  Salix brachycarpa ssp. brachycarpa Nutt. -- not accepted -- barrenground willow, short-fruited willow
  Salix brachycarpa ssp. brachycarpa var. brachycarpa Nutt. -- not accepted
  Salix brachycarpa var. brachycarpa Nutt. -- accepted -- shortfruit willow
  Salix caudata (Nutt.) A. Heller -- not accepted
  Salix cordata var. lutea (Nutt.) Bebb -- not accepted
  Salix cuneata Nutt. -- not accepted
  Salix exigua Nutt. -- accepted -- coyote willow, desert willow, narrowleaf willow, sandbar willow
  Salix exigua ssp. melanopsis (Nutt.) Cronquist -- not accepted
  Salix exigua var. exigua Nutt. -- accepted -- coyote willow, narrowleaf willow
  Salix exigua var. sessilifolia (Nutt.) Dorn -- not accepted
  Salix flavescens Nutt. -- not accepted
  Salix fluviatilis Nutt. -- not accepted -- river willow
  Salix fluviatilis auct. non Nutt. -- not accepted -- river willow
  Salix fluviatilis var. argophylla (Nutt.) Sarg. -- not accepted
  Salix fluviatilis var. sessilifolia (Nutt.) Scoggan -- not accepted
  Salix labradorica var. pumila Nutt. -- not accepted
  Salix lasiandra ssp. caudata (Nutt.) A.E. Murray -- not accepted
  Salix lasiandra var. caudata (Nutt.) Sudw. -- accepted -- greenleaf willow
  Salix longifolia var. argophylla (Nutt.) Andersson -- not accepted
  Salix longifolia var. exigua (Nutt.) Bebb -- not accepted
  Salix longifolia var. sessilifolia (Nutt.) M.E. Jones -- not accepted
  Salix lucida ssp. caudata (Nutt.) A.E. Murray -- not accepted -- greenleaf willow, shining willow
  Salix lutea Nutt. -- accepted -- yellow willow
  Salix macrocarpa Nutt. -- not accepted
  Salix macrostachya Nutt. -- not accepted
  Salix malacophylla Nutt. ex C.R. Ball -- not accepted
  Salix melanopsis Nutt. -- accepted -- dusky willow
  Salix pentandra var. caudata Nutt. -- not accepted
  Salix rotundifolia Nutt. -- not accepted -- least willow
  Salix scouleriana var. flavescens (Nutt.) J.K. Henry -- not accepted
  Salix sessilifolia Nutt. -- accepted -- northwest sandbar willow, northwest willow
  Salix speciosa Nutt. -- not accepted
  Salix stagnalis Nutt. -- not accepted
  Salsola kali var. caroliniana (Walter) Nutt. -- not accepted
  Sambucus glauca Nutt. -- not accepted
  Sanguisorba annua (Nutt.) Nutt. -- not accepted -- prairie burnet
  Sanguisorba occidentalis Nutt. -- not accepted -- western burnet
  Sassafras albidum (Nutt.) Nees -- accepted -- sassafras
  Satureja arkansana (Nutt.) Briq. -- not accepted
  Satureja coccinea (Nutt. ex Hook.) Bertol. -- not accepted
  Satureja glabra (Nutt.) Fernald -- not accepted
  Scaevola coriacea Nutt. -- accepted -- dwarf naupaka
  Schedonnardus paniculatus (Nutt.) Branner & Coville -- not accepted -- tumble grass, tumbleggrass, tumblegrass
  Schmaltzia trilobata (Nutt.) Small -- not accepted
  Schoenocrambe linifolia (Nutt.) Greene -- not accepted -- flaxleaf plainsmustard, rush mustard
  Sclerachne arkansana (Nutt.) Torr. ex Trin. -- not accepted
  Scorzonella Nutt. -- not accepted
  Scorzonella leptosepala Nutt. -- not accepted
  Scutellaria ambigua Nutt. -- not accepted
  Scutellaria nervosa var. ambigua (Nutt.) Fernald -- not accepted
  Scutellaria ovata ssp. versicolor (Nutt.) Epling -- not accepted
  Scutellaria ovata var. versicolor (Nutt.) Fernald -- not accepted
  Sedum cymosum (Nutt.) Fröd. -- not accepted
  Sedum oreganum Nutt. -- accepted -- Oregon stonecrop
  Sedum oreganum ssp. oreganum Nutt. -- not accepted -- Oregon stonecrop
  Sedum oreganum var. oreganum Nutt. -- accepted -- Oregon stonecrop
  Selenia Nutt. -- not accepted
  Selenia Nutt. -- accepted
  Selenia aurea Nutt. -- accepted -- golden selenia, yellow selenia
  Senecio cymbalarioides Nutt. non Senecio cymbalarioides H. Buek -- not accepted -- cleftleaf groundsel
  Senecio debilis Nutt. -- not accepted -- weak groundsel
  Senecio exaltatus Nutt. -- not accepted
  Senecio filifolius Nutt. non P.J. Bergius -- not accepted
  Senecio hydrophilus Nutt. -- accepted -- alkali marsh groundsel, water groundsel, water ragwort
  Senecio integerrimus Nutt. -- accepted -- lamb-tongue ragwort, lambstongue groundsel, lambstongue ragwort
  Senecio integerrimus var. exaltatus (Nutt.) Cronquist -- accepted -- Columbia groundsel, Columbia ragwort
  Senecio integerrimus var. integerrimus Nutt. -- accepted -- lambstongue ragwort
  Senecio lugens var. exaltatus (Nutt.) A. Gray -- not accepted
  Senecio megacephalus Nutt. -- accepted -- rocky ragwort
  Senecio plattensis Nutt. -- not accepted -- prairie groundsel
  Senecio purshianus Nutt. -- not accepted
  Senecio rapifolius Nutt. -- accepted -- openwoods ragwort
  Senecio schweinitizianus Nutt. -- not accepted
  Senecio schweinitzianus Nutt. -- not accepted -- Schweinitz's ragwort
  Sericocarpus oregonensis Nutt. -- accepted -- Oregon whitetop aster
  Sericocarpus oregonensis ssp. oregonensis Nutt. -- accepted -- Oregon whitetop aster
  Sericocarpus oregonensis var. oregonensis Nutt. -- not accepted -- Oregon whitetop aster
  Seriphidium arbusculum (Nutt.) W.A. Weber -- not accepted
  Seriphidium rigidum (Nutt.) W.A. Weber -- not accepted
  Seriphidium tridentatum (Nutt.) W.A. Weber -- not accepted
  Sesleria dactyloides Nutt. -- not accepted
  Setaria glauca var. laevigata (Nutt.) Chapm. -- not accepted
  Setaria laevigata (Nutt.) Schult. -- not accepted
  Seymeria macrophylla Nutt. -- not accepted
  Shepherdia Nutt. -- accepted -- buffaloberries, buffaloberry
  Shepherdia argentea (Pursh) Nutt. -- accepted -- silver buffaloberry
  Shepherdia canadensis (L.) Nutt. -- accepted -- russet buffalo-berry, russet buffaloberry
  Sidalcea malviflora ssp. californica (Nutt. ex Torr. & A. Gray) C.L. Hitchc. -- accepted -- California checkerbloom
  Sidalcea malviflora var. californica (Nutt. ex Torr. & A. Gray) Jeps. -- not accepted
  Sidalcea oregana (Nutt. ex Torr. & A. Gray) A. Gray -- accepted -- Oregon checkerbloom, Oregon checkermallow
  Sidalcea oregana ssp. oregana (Nutt. ex Torr. & A. Gray) A. Gray -- accepted -- Oregon checkerbloom, Oregon checkermallow
  Sidalcea oregana ssp. oregana var. oregana (Nutt. ex Torr. & A. Gray) A. Gray -- not accepted -- Oregon checkerbloom, Oregon checkermallow
  Sidalcea oregana var. oregana (Nutt. ex Torr. & A. Gray) A. Gray -- not accepted -- Oregon checkerbloom
  Sideranthus gracilis (Nutt.) A. Nelson -- not accepted
  Sideranthus grindelioides (Nutt.) Britton -- not accepted
  Sideroxylon lanuginosum ssp. oblongifolium (Nutt.) T.D. Penn. -- accepted -- gum bully
  Sideroxylon macrocarpum (Nutt.) J.R. Allison -- accepted -- large-fruited bully
  Sieglingia stricta (Nutt.) Kuntze -- not accepted
  Silene baldwinii Nutt. -- not accepted
  Silene hookeri Nutt. -- accepted -- Hooker's silene
  Silene hookeri ssp. hookeri Nutt. -- accepted -- Hooker's silene
  Silene nivea (Nutt.) Muhl. ex Otth -- accepted -- evening campion
  Silene rotundifolia Nutt. -- accepted -- roundleaf catchfly
  Silphium asteriscus var. scabrum Nutt. -- not accepted
  Silphium compositum ssp. reniforme (Raf. ex Nutt.) Sweeny & T.R. Fisher -- not accepted
  Silphium compositum var. reniforme (Raf. ex Nutt.) Torr. & A. Gray -- not accepted -- kidneyleaf rosinweed
  Silphium radula Nutt. -- accepted -- roughstem rosinweed, starry rosinweed
  Silphium radula var. radula Nutt. -- accepted -- Reverchon's rosinweed
  Silphium reniforme Raf. ex Nutt. -- not accepted
  Silphium speciosum Nutt. -- not accepted
  Simmondsia Nutt. -- accepted -- goatnut, jojoba
  Simmondsia californica Nutt. -- not accepted
  Siphonychia americana (Nutt.) Torr. & A. Gray -- not accepted
  Sisymbrium linifolium (Nutt.) Nutt. ex Torr. & A. Gray -- accepted -- flaxleaf plainsmustard
  Sisymbrium virgatum Nutt. -- not accepted
  Sitanion hystrix (Nutt.) J.G. Sm. -- not accepted
  Sitanion hystrix var. hystrix (Nutt.) J.G. Sm. -- not accepted
  Sitilias grandiflora (Nutt.) Greene -- not accepted
  Smilacina amplexicaulis Nutt. -- not accepted
  Smilacina racemosa var. amplexicaulis (Nutt.) S. Watson -- not accepted
  Smilacina sessilifolia Nutt. ex Baker -- not accepted
  Solanum carolinense var. hirsutum (Nutt.) A. Gray -- not accepted -- apple of Sodom, bull nettle, Carolina horsenettle, devil's tomato, horsenettle, sand briar
  Solanum puberulum Nutt. ex Seem. -- not accepted
  Solanum triflorum Nutt. -- accepted -- cut-leaf nightshade, cutleaf nightshade
  Solidago californica Nutt. -- not accepted -- California goldenrod
  Solidago canadensis ssp. elongata (Nutt.) D.D. Keck -- not accepted
  Solidago canadensis var. elongata (Nutt.) M. Peck -- not accepted
  Solidago elongata Nutt. -- accepted
  Solidago gigantea var. pitcheri (Nutt.) Shinners -- not accepted
  Solidago glutinosa Nutt. -- not accepted
  Solidago lepida var. elongata (Nutt.) Fernald -- not accepted
  Solidago missouriensis Nutt. -- accepted -- Missouri goldenrod, prairie goldenrod, Tolmie's goldenrod
  Solidago missouriensis var. missouriensis Nutt. -- not accepted -- Missouri goldenrod
  Solidago nana Nutt. -- accepted -- baby goldenrod, gray goldenrod
  Solidago occidentalis (Nutt.) Torr. & A. Gray -- not accepted
  Solidago pitcheri Nutt. -- not accepted
  Solidago puberula Nutt. -- accepted -- downy goldenrod
  Solidago puberula ssp. puberula Nutt. -- accepted -- downy goldenrod
  Solidago puberula ssp. pulverulenta (Nutt.) Semple -- accepted -- downy goldenrod
  Solidago puberula var. puberula Nutt. -- not accepted -- downy goldenrod
  Solidago puberula var. pulverulenta (Nutt.) Chapm. -- not accepted -- downy goldenrod
  Solidago pulverulenta Nutt. -- not accepted
  Solidago radula Nutt. -- accepted -- rough goldenrod, western rough goldenrod
  Solidago radula var. radula Nutt. -- not accepted -- western rough goldenrod
  Solidago spathulata ssp. glutinosa (Nutt.) D.D. Keck -- not accepted
  Solidago speciosa Nutt. -- accepted -- noble goldenrod, showy goldenrod
  Solidago speciosa ssp. speciosa Nutt. -- accepted
  Solidago speciosa var. speciosa Nutt. -- accepted -- showy goldenrod
  Solidago squarrosa Nutt. -- accepted -- stout goldenrod
  Solidago uliginosa Nutt. -- accepted -- bog goldenrod, fall goldenrod
  Solidago uliginosa var. uliginosa Nutt. -- not accepted -- bog goldenrod
  Solidago velutina ssp. califonica (Nutt.) Semple -- accepted -- California goldenrod
  Soliva daucifolia Nutt. -- not accepted
  Sophora sericea Nutt. -- not accepted
  Sparganium americanum Nutt. -- accepted -- American bur-reed, American burreed
  Specularia leptocarpa (Nutt.) A. Gray -- not accepted
  Specularia rariflora (Nutt.) McVaugh -- not accepted
  Spermolepis echinata (Nutt. ex DC.) A. Heller -- accepted -- bristly scaleseed, bristly-fruit scaleseed
  Spermolepis inermis (Nutt. ex DC.) Mathias & Constance -- accepted -- Red River scaleseed
  Spermolepis patens (Nutt. ex DC.) B.L. Rob. -- not accepted
  Sphaeralcea coccinea (Nutt.) Rydb. -- accepted -- copper mallow, orange globemallow, red falsemallow, scarlet globemallow
  Sphaeralcea coccinea ssp. coccinea (Nutt.) Rydb. -- accepted -- globemallow, scarlet globe-mallow, scarlet globemallow
  Sphaeralcea coccinea ssp. dissecta (Nutt. ex Torr. & A. Gray) Kearney -- not accepted
  Sphaeralcea coccinea var. dissecta (Nutt. ex Torr. & A. Gray) Garrett -- not accepted
  Sphaeromeria Nutt. -- accepted -- chickensage, sphaeromeria
  Sphaeromeria argentea Nutt. -- accepted -- silver chickensage
  Sphaeromeria capitata Nutt. -- accepted -- rock tansy
  Spiesia lagopus (Nutt.) Kuntze -- not accepted
  Spiraea caespitosa Nutt. -- not accepted
  Spiraea densiflora Nutt. ex Greenm. -- not accepted
  Spiraea dumosa Nutt. ex Hook. -- not accepted
  Spiranthes cernua var. odorata (Nutt.) Correll -- not accepted
  Spiranthes odorata (Nutt.) Lindl. -- accepted -- marsh ladies'-tresses, marsh ladiestresses, marsh lady's tresses
  Spirochloe paniculata (Nutt.) Lunell -- not accepted
  Sporobolus arkansanus Nutt. ex Vasey -- not accepted
  Stachys palustris ssp. pilosa (Nutt.) Epling -- not accepted -- marsh hedgenettle
  Stachys palustris var. pilosa (Nutt.) Fernald -- not accepted
  Stachys pilosa Nutt. -- accepted -- hairy hedgenettle
  Stachys pilosa var. pilosa Nutt. -- accepted -- hairy hedgenettle
  Stachys rigida Nutt. ex Benth. -- accepted -- rigid hedgenettle, rough hedgenettle
  Stachys rigida var. rigida Nutt. ex Benth. -- accepted -- rough hedgenettle
  Stanleya Nutt. -- accepted -- princes'-plume, princesplume
  Stanleya viridiflora Nutt. -- accepted -- green princesplume, perennial prince's-plume
  Starkea pinnata Nutt. -- not accepted
  Stebbinsoseris heterocarpa (Nutt.) K.L. Chambers -- accepted -- grassland silverpuffs, silverpuffs
  Stellaria nitens Nutt. -- accepted -- shiny chickweed, shiny starwort
  Stenochloa Nutt. -- not accepted
  Stenochloa californica Nutt. -- not accepted
  Stenogonum Nutt. -- accepted -- buckwheat
  Stenogonum salsuginosum Nutt. -- accepted -- salty buckwheat, salty eriogonum, smooth two-whorl buckwheat
  Stenosiphon liniflorus (Nutt. ex E. James) Heynh. -- not accepted
  Stenosiphon linifolius (Nutt. ex E. James) Heynh. -- not accepted -- false gaura, Stenosiphon
  Stenotus Nutt. -- accepted -- mock goldenweed, stenotus
  Stenotus acaulis (Nutt.) Nutt. -- accepted -- stemless goldenweed, stemless mock goldenweed
  Stenotus acaulis var. acaulis (Nutt.) Nutt. -- not accepted -- stemless goldenweed, stemless mock goldenweed
  Stenotus armerioides Nutt. -- accepted -- thrift mock goldenweed
  Stenotus armerioides var. armerioides Nutt. -- accepted -- goldenweed, thrift mock goldenweed, thrifty goldenweed
  Stephanomeria Nutt. -- accepted -- wire lettuce, wirelettuce
  Stephanomeria elata Nutt. -- accepted -- Santa Barbara wirelettuce
  Stephanomeria exigua Nutt. -- accepted -- small wirelettuce, wire lettuce
  Stephanomeria exigua ssp. exigua Nutt. -- accepted -- Schott's wirelettuce, small wirelettuce, wire lettuce
  Stephanomeria minor (Hook.) Nutt. -- not accepted -- lesser wirelettuce
  Stephanomeria minor var. minor (Hook.) Nutt. -- not accepted -- narrowleaf wirelettuce
  Stephanomeria paniculata Nutt. -- accepted -- tufted wirelettuce
  Stephanomeria runcinata Nutt. -- accepted -- desert wirelettuce, flowering-straw
  Stephanomeria spinosa (Nutt.) S. Tomb -- not accepted -- spiny skeletonweed, thorn skeletonweed, thorny wire-lettuce
  Stipa parviflora Nutt. ex Steud. -- not accepted
  Stipa robusta Nutt. ex Trin. & Rupr. -- not accepted
  Streptanthus Nutt. -- accepted -- twistflower
  Streptanthus arcuatus Nutt. -- not accepted
  Streptanthus cordatus Nutt. -- accepted -- heartleaf twistflower
  Streptanthus cordatus var. cordatus Nutt. -- accepted -- heartleaf twistflower
  Streptanthus heterophyllus Nutt. -- not accepted
  Streptanthus maculatus Nutt. -- accepted -- clasping jewelflower, clasping twistflower
  Streptanthus maculatus ssp. maculatus Nutt. -- not accepted -- clasping jewelflower
  Stutzia dioica (Nutt.) E.H. Zacharias -- accepted
  Stylocline Nutt. -- accepted -- neststraw, stylocline
  Stylocline gnaphalioides Nutt. -- not accepted -- mountain neststraw
  Stylocline gnaphaloides Nutt. -- accepted -- mountain neststraw
  Stylopappus elatus Nutt. -- not accepted
  Stylophorum Nutt. -- accepted
  Stylophorum diphyllum (Michx.) Nutt. -- accepted -- celandine poppy
  Stylophyllum edule (Nutt.) Britton & Rose -- not accepted
  Symphoricarpos albus var. mollis (Nutt.) D.D. Keck -- not accepted
  Symphoricarpos mollis Nutt. -- accepted -- creeping snowberry
  Symphyotrichum adnatum (Nutt.) G.L. Nesom -- accepted -- scaleleaf aster
  Symphyotrichum bracteolatum auct. non (Nutt.) G.L. Nesom -- not accepted
  Symphyotrichum campestre (Nutt.) G.L. Nesom -- accepted -- western meadow aster
  Symphyotrichum campestre var. bloomeri (Nutt.) G.L. Nesom -- not accepted -- Bloomer's aster
  Symphyotrichum campestre var. campestre (Nutt.) G.L. Nesom -- not accepted -- western meadow aster
  Symphyotrichum divaricatum (Nutt.) G.L. Nesom -- not accepted -- southern annual saltmarsh aster
  Symphyotrichum frondosum (Nutt.) G.L. Nesom -- accepted -- short-rayed alkali aster
  Symphyotrichum oblongifolium (Nutt.) G.L. Nesom -- accepted -- aromatic aster
  Symphyotrichum X amethystinum (Nutt.) G.L. Nesom -- accepted
  Symplocarpus Salisb. ex Nutt. -- accepted -- skunk cabbage
  Symplocarpus foetidus (L.) Salisb. ex Nutt. -- not accepted
  Synadra Nutt. -- not accepted
  Synandra Nutt. -- accepted
  Talinum parviflorum Nutt. -- not accepted -- prairie flameflower, sunbright, sunbright talinum
  Tanacetum bipinnatum ssp. huronense (Nutt.) Breitung -- not accepted -- Lake Huron tansy
  Tanacetum capitatum (Nutt.) Torr. & A. Gray -- not accepted
  Tanacetum horonense Nutt. -- not accepted
  Tanacetum huronense Nutt. -- not accepted
  Taraxia (Nutt. ex Torr. & A. Gray) Raim. -- accepted
  Taraxia breviflora (Torr. & A. Gray) Nutt. ex Small -- accepted -- fewflower evening primrose
  Taraxia ovata (Nutt.) Small -- accepted -- goldeneggs
  Taxodium distichum var. imbricarium (Nutt.) Croom -- accepted
  Taxus brevifolia Nutt. -- accepted -- Pacific yew
  Taxus floridana Nutt. ex Chapm. -- accepted -- Florida yew
  Tephrosia elegans Nutt. -- not accepted
  Tephrosia onobrychoides Nutt. -- accepted -- multibloom hoarypea, multibloom tephrosia
  Tephrosia virginiana var. glabra Nutt. ex Torr. & A. Gray -- not accepted
  Tephrosia virginiana var. holosericea (Nutt.) Torr. & A. Gray -- not accepted
  Tessaria sericea (Nutt.) Shinners -- not accepted
  Tetraneuris glabra (Nutt.) Greene -- not accepted
  Tetraneuris scaposa var. linearis (Nutt.) Parker -- not accepted -- plains tetraneuris, stemmy four-nerve daisy
  Tetraneuris torreyana (Nutt.) Greene -- accepted -- flat four-nerve daisy, stone rubberweed, Torrey's four-nerve daisy
  Thalesia fasciculata (Nutt.) Britton -- not accepted
  Thaspium Nutt. -- accepted -- meadowparsnip
  Thaspium aureum (L.) Nutt. -- not accepted
  Thaspium barbinode (Michx.) Nutt. -- accepted -- hairyjoint meadowparsnip, hairyspine thaspium
  Thelypodiopsis sagittata (Nutt.) O.E. Schulz -- not accepted
  Thelypodium integrifolium (Nutt.) Endl. ex Walp. -- accepted -- entire-leaf thelypody, entireleaf thelypody, entireleaved thelypody, smoothleaved thelypody
  Thelypodium integrifolium ssp. integrifolium (Nutt.) Endl. ex Walp. -- accepted -- entire-leaf thelypody, entireleaved thelypody
  Thelypodium sagittatum (Nutt. ex Torr. & A. Gray) Endl. ex Walp. -- accepted -- arrow thelypody, slender thelypody
  Thelypodium sagittatum ssp. sagittatum (Nutt. ex Torr. & A. Gray) Endl. ex Walp. -- accepted -- arrow thelypody
  Thermopsis fraxinifolia (Nutt. ex Torr. & A. Gray) M.A. Curtis -- accepted -- ashleaf goldenbanner
  Thermopsis macrophylla var. montana (Nutt.) Isely -- not accepted
  Thermopsis mollis var. fraxinifolia (Nutt. ex M.A. Curtis) Isely -- not accepted
  Thermopsis montana Nutt. -- accepted -- mountain goldenbanner
  Thermopsis montana var. montana Nutt. -- accepted -- goldenpea, mountain goldenbanner
  Thermopsis rhombifolia (Nutt. ex Pursh) Nutt. ex Richardson -- accepted -- goldenpea, prairie thermopsis
  Thermopsis rhombifolia var. montana (Nutt.) Isely -- not accepted -- mountain thermopsis
  Thermopsis rhombifolia var. rhombifolia (Nutt. ex Pursh) Nutt. ex Richardson -- not accepted -- prairie goldenbanner
  Therofon aconitifolium (Nutt.) Millsp. -- not accepted
  Thurberia arkansana (Nutt.) Benth. ex Vasey -- not accepted
  Thysanocarpus laciniatus Nutt. -- accepted -- mountain fringepod, narrowleaf lacepod, Santa Cruz Island fringepod
  Thysanocarpus laciniatus var. crenatus (Nutt.) W.H. Brewer -- not accepted
  Thysanocarpus laciniatus var. laciniatus Nutt. -- not accepted -- mountain fringepod
  Tidestromia lanuginosa (Nutt.) Standl. -- accepted -- honeymat, woolly tidestromia
  Tilia heterophylla var. michauxii (Nutt.) Sarg. -- not accepted
  Tilia michauxii Nutt. -- not accepted
  Tillaea angustifolia Nutt. -- not accepted
  Tipularia Nutt. -- accepted
  Tipularia discolor (Pursh) Nutt. -- accepted -- crippled cranefly
  Tofieldia glabra Nutt. -- accepted -- smooth bog-asphodel, smooth tofieldia
  Tonella Nutt. ex A. Gray -- accepted
  Townsendia grandiflora Nutt. -- accepted -- largeflower Townsend daisy
  Townsendia incana Nutt. -- accepted -- hoary Townsend daisy, hoary townsend-daisy, hoary townsendia
  Townsendia spathulata Nutt. -- accepted -- sword Townsend daisy
  Townsendia strigosa Nutt. -- accepted -- hairy Townsend daisy, hairy Townsend-daisy, hairy townsendia
  Toxicoscordion paniculatum (Nutt.) Rydb. -- accepted -- foothill deathcamas
  Trachyphytum gracile Nutt. -- not accepted
  Tragia angustifolia Nutt. -- not accepted
  Tragia betonicifolia Nutt. -- accepted -- betonyleaf noseburn
  Transberingia bursifolia ssp. virgata (Nutt.) Al-Shehbaz & O'Kane -- accepted
  Trautvetteria grandis Nutt. -- not accepted
  Trepocarpus Nutt. ex DC. -- accepted
  Trepocarpus aethusae Nutt. ex DC. -- accepted -- whitenymph
  Triantha (Nutt.) Baker -- accepted
  Tricuspis stricta (Nutt.) Alph. Wood -- not accepted
  Tridens strictus (Nutt.) Nash -- accepted -- longspike tridens
  Trifolium andinum Nutt. -- accepted -- Great Divide clover, Intermountain clover
  Trifolium andinum var. andinum Nutt. -- accepted -- Intermountain clover
  Trifolium depauperatum var. diversifolium (Nutt.) McDermott -- accepted -- balloon sack clover
  Trifolium depauperatum var. stenophyllum (Nutt.) McDermott -- accepted -- balloon sack clover
  Trifolium eriocephalum Nutt. -- accepted -- woollyhead clover
  Trifolium eriocephalum ssp. eriocephalum Nutt. -- accepted -- woollyhead clover
  Trifolium fucatum var. gambelii (Nutt.) Jeps. -- not accepted
  Trifolium gambelii Nutt. -- not accepted
  Trifolium gymnocarpon Nutt. -- accepted -- hollyleaf clover
  Trifolium gymnocarpon ssp. gymnocarpon Nutt. -- accepted -- hollyleaf clover
  Trifolium longipes Nutt. -- accepted -- long-stalk clover, longstalk clover
  Trifolium longipes ssp. longipes Nutt. -- accepted -- longstalk clover
  Trifolium pauciflorum Nutt. -- not accepted
  Trifolium stenophyllum Nutt. -- not accepted
  Trifolium tridentatum var. aciculare (Nutt.) McDermott -- not accepted
  Trifolium variegatum Nutt. -- accepted -- white-tip clover, whitetip clover
  Trifolium variegatum var. pauciflorum (Nutt.) McDermott -- not accepted
  Triglochin elata Nutt. -- not accepted
  Triglochin elatum Nutt. -- not accepted
  Triglochin maritima var. elata (Nutt.) A. Gray -- not accepted
  Triglochin maritimum var. elatum (Nutt.) A. Gray -- not accepted
  Trillium viridescens Nutt. -- accepted -- tapertip wakerobin
  Triodanis leptocarpa (Nutt.) Nieuwl. -- accepted -- slimpod Venus' looking-glass, Venus' lookingglass
  Triodia stricta (Nutt.) Benth. ex Vasey -- not accepted
  Triphora Nutt. -- accepted -- noddingcaps
  Tripolium frondosum Nutt. -- not accepted
  Tripolium occidentale Nutt. -- not accepted
  Tripolium oregonum Nutt. -- not accepted
  Trisetum elatum Nutt. ex A. Gray -- not accepted
  Troximon grandiflorum Nutt. -- not accepted
  Troximon parviflorum Nutt. -- not accepted
  Tuckermannia maritima Nutt. -- not accepted
  Ulmus crassifolia Nutt. -- accepted -- cedar elm
  Umbellularia (Nees) Nutt. -- accepted -- California laurel, Californian bay
  Umbellularia californica (Hook. & Arn.) Nutt. -- accepted -- California laurel
  Umbellularia californica var. californica (Hook. & Arn.) Nutt. -- accepted -- California laurel
  Unamia alba (Nutt.) Rydb. -- not accepted
  Uniola multiflora Nutt. -- not accepted
  Uralepis Nutt. -- not accepted
  Uralepis aristulata Nutt. -- not accepted
  Uralepis purpurea (Walter) Nutt. -- not accepted
  Uropappus Nutt. -- accepted -- silverpuffs, Uropappus
  Uropappus lindleyi (DC.) Nutt. -- accepted -- Lindley's silverpuffs
  Uropappus linearifolius Nutt. -- not accepted
  Urtica dioica ssp. holosericea (Nutt.) Thorne -- accepted -- hoary stinging nettle, slim nettle, stinging nettle
  Urtica dioica var. holoserica (Nutt.) Thorne -- not accepted
  Urtica dioica var. holosericea (Nutt.) C.L. Hitchc. -- not accepted
  Urtica gracilis ssp. holosericea (Nutt.) W.A. Weber -- not accepted
  Urtica gracilis var. holosericea (Nutt.) Jeps. -- not accepted
  Urtica holosericea Nutt. -- not accepted
  Vagnera amplexicaulis (Nutt.) Greene -- not accepted
  Vagnera sessilifolia (Nutt. ex Baker) Greene -- not accepted
  Valeriana edulis Nutt. ex Torr. & A. Gray -- accepted -- edible valerian, tobacco root, tobaccoroot
  Valeriana edulis var. edulis Nutt. ex Torr. & A. Gray -- accepted -- tobacco root
  Verbena bipinnatifida Nutt. -- not accepted
  Verbesina laciniata (Poir.) Nutt. -- not accepted
  Verbesina nudicaulis (Nutt.) A. Gray -- not accepted
  Verbesina pauciflora (Nutt.) Small non Hemsl. -- not accepted
  Vernonia altissima Nutt. -- not accepted
  Vernonia angustifolia ssp. scaberrima (Nutt.) S.B. Jones & Faust -- not accepted -- tall ironweed
  Vernonia angustifolia var. scaberrima (Nutt.) A. Gray -- not accepted
  Vernonia scaberrima Nutt. -- not accepted
  Vesicaria alpina Nutt. -- not accepted
  Vicia americana ssp. oregana (Nutt.) Abrams -- not accepted
  Vicia americana var. linearis (Nutt.) S. Watson -- not accepted
  Vicia americana var. oregana (Nutt.) A. Nelson -- not accepted
  Vicia americana var. truncata (Nutt.) W.H. Brewer -- not accepted
  Vicia exigua Nutt. -- not accepted
  Vicia leavenworthii Nutt. ex Torr. & A. Gray -- not accepted
  Vicia linearis (Nutt.) Greene -- not accepted
  Vicia ludoviciana Nutt. ex Torr. & A. Gray -- accepted -- deerpea vetch, Louisiana vetch, slim vetch
  Vicia ludoviciana ssp. leavenworthii (Nutt. ex Torr. & A. Gray) Lassetter & C.R. Gunn -- not accepted -- Leavenworth's vetch
  Vicia ludoviciana ssp. ludoviciana Nutt. ex Torr. & A. Gray -- not accepted -- Louisiana vetch, slim vetch
  Vicia ludoviciana var. leavenworthii (Nutt. ex Torr. & A. Gray) Broich -- accepted -- Leavenworth's vetch
  Vicia ludoviciana var. ludoviciana Nutt. ex Torr. & A. Gray -- accepted -- Louisiana vetch
  Vicia micrantha Nutt. ex Torr. & A. Gray -- not accepted
  Vicia oregana Nutt. -- not accepted
  Vicia sparsifolia Nutt. ex Torr. & A. Gray -- not accepted
  Vicia sparsifolia var. truncata (Nutt.) S. Watson -- not accepted
  Viguiera multiflora (Nutt.) S.F. Blake -- not accepted
  Viola canadensis var. corymbosa Nutt. ex Torr. & A. Gray -- not accepted -- Canadian white violet
  Viola emarginata (Nutt.) Leconte -- not accepted
  Viola glabella Nutt. -- accepted -- pioneer violet
  Viola linguifolia Nutt. -- not accepted
  Viola nuttallii var. linguifolia (Nutt.) Jeps. -- not accepted
  Viola praemorsa ssp. linguifolia (Nutt.) M.S. Baker & J.C. Clausen ex M. Peck -- not accepted -- upland yellow violet
  Viola praemorsa var. linguifolia (Nutt.) M. Peck -- accepted -- upland yellow violet
  Viola pubescens var. eriocarpa Nutt. -- not accepted
  Viola pubescens var. eriocarpon Nutt. -- not accepted
  Viola sagittata var. ovata (Nutt.) Torr. & A. Gray -- accepted -- arrowleaf violet
  Viola X cordifolia (Nutt.) Schwein. (pro sp.) -- accepted -- violet
  Virgulus adnatus (Nutt.) Reveal & Keener -- not accepted
  Virgulus campestris (Nutt.) Reveal & Keener -- not accepted
  Virgulus oblongifolius (Nutt.) Reveal & Keener -- not accepted
  Virgulus X amethystinus (Nutt.) Reveal & Keener -- not accepted
  Vulpia megalura (Nutt.) Rydb. -- not accepted
  Vulpia microstachys (Nutt.) Munro -- accepted -- little fescue, small fescue, twoflower fescue
  Vulpia microstachys var. microstachys (Nutt.) Munro -- accepted -- desert fescue
  Vulpia myuros f. megalura (Nutt.) Stace & R. Cotton -- not accepted
  Vulpia myuros ssp. megalura (Nutt.) Soják -- not accepted
  Vulpia myuros var. megalura (Nutt.) Auquier -- accepted
  Vulpia octoflora var. glauca (Nutt.) Fernald -- accepted -- eight-flower six-weeks grass, sixweeks fescue
  Vulpia sciurea (Nutt.) Henrard -- not accepted -- squirreltail fescue
  Warea Nutt. -- accepted -- pinelandcress
  Warea amplexifolia (Nutt.) Nutt. -- accepted -- wide-leaf warea, wideleaf pinelandcress
  Warea cuneifolia (Muhl. ex Nutt.) Nutt. -- accepted -- Carolina pinelandcress
  Windsoria Nutt. -- not accepted
  Windsoria ambigua (Elliott) Nutt. -- not accepted
  Windsoria poiformis Nutt. -- not accepted
  Windsoria stricta Nutt. -- not accepted
  Wisteria Nutt. -- accepted -- wisteria
  Wisteria macrostachya (Torr. & A. Gray) Nutt. ex B.L. Rob. & Fernald -- not accepted
  Wyethia Nutt. -- accepted -- mule-ears, wyethia
  Wyethia amplexicaulis (Nutt.) Nutt. -- accepted -- mule's ear wyethia, mule-ears, mulesear wyethia
  Wyethia angustifolia (DC.) Nutt. -- accepted -- California compassplant
  Wyethia helenioides (DC.) Nutt. -- accepted -- whitehead mule-ears
  Wyethia helianthoides Nutt. -- accepted -- sunflower mule-ears, whitehead wyethia
  X Asplenosorus pinnatifidus (Nutt.) Mickel -- not accepted
  Xanthisma gracile (Nutt.) D.R. Morgan & R.L. Hartm. -- accepted -- slender goldenweed
  Xanthisma grindelioides (Nutt.) D.R. Morgan & R.L. Hartm. -- accepted -- goldenweed, gumweed aster, rayless tansyaster
  Xanthisma grindelioides var. grindelioides (Nutt.) D.R. Morgan & R.L. Hartm. -- accepted -- goldenweed, gumweed aster
  Xanthoxalis pilosa (Nutt.) Small -- not accepted
  Xerophyllium asphodeloides (L.) Nutt. -- not accepted
  Xerophyllium tenax (Pursh) Nutt. -- not accepted
  Xerophyllum asphodeloides (L.) Nutt. -- accepted -- eastern turkeybeard
  Xerophyllum tenax (Pursh) Nutt. -- accepted -- common beargrass
  Xylococcus Nutt. -- accepted -- mission manzanita
  Xylococcus bicolor Nutt. -- accepted -- mission manzanita
  Xylophacos argophyllus (Nutt.) Rydb. -- not accepted
  Xylophacos missouriensis (Nutt.) Rydb. -- not accepted
  Xylorhiza Nutt. -- accepted -- woodyaster, xylorhiza
  Xylorhiza glabriuscula Nutt. -- accepted -- common woody aster, smooth woodyaster, woody aster
  Xylorhiza glabriuscula var. glabriuscula Nutt. -- not accepted -- smooth woodyaster
  Xylorhiza glabriuscula var. villosa (Nutt.) A. Nelson -- not accepted -- villous woodyaster
  Xylorhiza villosa Nutt. -- not accepted
  Yucca californica Nutt. ex Baker -- not accepted
  Yucca glauca Nutt. -- accepted -- beargrass, Great Plains yucca, small soapweed, soapweed yucca, Spanish bayonet, yucca
  Yucca glauca var. glauca Nutt. -- not accepted -- narrowleaf yucca, soapweed yucca
  Zanthoxylum macrophyllum Nutt. -- not accepted
  Zigadenus elegans ssp. glaucus (Nutt.) Hultén -- not accepted -- mountain deathcamas
  Zigadenus elegans var. glaucus (Nutt.) Cronquist -- not accepted
  Zigadenus glaucus Nutt. -- not accepted
  Zigadenus paniculatus (Nutt.) S. Watson -- not accepted -- foothill deathcamas, sand-corn
  Zinnia grandiflora Nutt. -- accepted -- plains zinnia, Rocky Mountain zinnia, Texas zinnia
  Zygophyllidium hexagonum (Nutt. ex Spreng.) Small -- not accepted
   

A gray bar