VegeWorx Plant Index - Letter T
- Tabacon Aspero - Solanum Rugosum Dunal
- Tabardillo - Calliandra Californica Benth.
- Tabebuia Argentea (Bureau & K. Schum.) Britton
- Tabebuia Caraiba (Mart.) Bureau
- Tabebuia Glomerata Urb.
- Tabebuia Heterophylla (DC.) Britton ssp. pallida auct. non (Miers) Stehlé
- Tabebuia Lucida Britton
- Tabebuia Pallida sensu Liogier & Martorell, non Miers
- Tabebuia Pentaphylla (DC.) Hemsl.
- Tabebuia Triphylla DC.
- Tabernaemontana Amygdalifolia Jacq. [excluded]
- Tabernaemontana Coronaria (L.) Willd.
- Tabernaemontana Oppositifolia (Spreng.) Urb.
- Tabernaemontana Rotensis (Kaneh.) Fosberg ex Stone
- Table Mountain Pine - Pinus Pungens Lamb.
- Table Townsend Daisy - Townsendia Mensana M.E. Jones
- Tacca Involucrata Schumach. & Thonn.
- Tacca Pinnatifida J.R. Forst. & G. Forst.
- Tacca - Tacca J.r. Forst. & G. Forst.
- Tacca - Tacca Palmata Blume
- Tachibana Orange - Citrus Tachibana (Makino) T. Tanaka
- Tackstem - Calycoseris A. Gray
- Tacky Goldenweed - Pyrrocoma Hirta (A. Gray) Greene
- Tacky Goldenweed - Pyrrocoma Hirta (A. Gray) Greene var. hirta
- Tacky Goldenweed - Pyrrocoma Hirta (A. Gray) Greene var. lanulosa (Greene) Mayes ex G. Brown & Keil
- Tacky Goldenweed - Pyrrocoma Hirta (A. Gray) Greene var. sonchifolia (Greene) Kartesz & Gandhi
- Tacky Phacelia - Phacelia Viscida (Benth. ex Lindl.) Torr.
- Tacoma Reedgrass - Calamagrostis Tacomensis K.L.Marr & Hebda
- Tacsonia Mollissima Kunth
- Tadpole Buttercup - Ranunculus Ranunculinus (Nutt.) Rydb.
- Taeniatherum Asperum auct. non (Simonkai) Nevski
- Taeniatherum Caput-medusae (L.) Nevski ssp. crinitum (Schreb.) Melderis
- Taeniatherum Crinitum (Schreb.) Nevski [excluded]
- Taeniatherum Crinitum (Schreb.) Nevski var. caput-medusae (L.) Wipff
- Taenidia - Taenidia (torr. & A. Gray) Drude
- Taeniophyllum - Taeniophyllum Blume
- Tafetan - Palicourea Alpina (Sw.) DC.
- Tagasaste - Chamaecytisus Palmensis (Christ) F.A. Bisby & K.W. Nicholls [excluded]
- Tagetes Alamensis Rydb.
- Tagetes Bonariensis Pers.
- Tagetes Corymbosa Sweet
- Tagetes Fragrantissima Sessé & Moc.
- Tagetes Glandulifera Schrank
- Tagetes Glandulosa Schrank ex Link
- Tagetes Major Gaertn.
- Tagetes Palmeri A. Gray
- Tagetes Papposa Vent.
- Tagetes Porophylla Vell.
- Tagetes Remotiflora Kunze
- Tagetes Rotundifolia Mill.
- Tagetes Signata Bartling
- Tagetes Tenuifolia Millsp.
- Tagua Tagua - Passiflora Serratodigitata L.
- Tahawas Porpidia Lichen - Porpidia Tahawasiana Gowan
- Tahiti Bristle Fern - Trichomanes Tahitense Nadeaud
- Tahitian Bridalveil - Gibasis Geniculata (Jacq.) Rohw.
- Tahitian Gardenia - Gardenia Taitensis DC.
- Tahitian Gooseberry Tree - Phyllanthus Acidus (L.) Skeels
- Tahitian Kidneywood - Eysenhardtia Orthocarpa (A. Gray) S. Watson
- Tahitian Screwpine - Pandanus Tectorius Parkinson ex Zucc.
- Tahitian Spinach - Xanthosoma Brasiliense (Desf.) Engl.
- Tahoe Sedge - Carex Tahoensis Smiley
- Tahquitz Mousetail - Ivesia Callida (H.M. Hall) Rydb.
- Tail Grape - Artabotrys R. Br.
- Tailcup Lupine - Lupinus Caudatus Kellogg
- Tailcup Lupine - Lupinus Caudatus Kellogg ssp. caudatus
- Tailed Grapefern - Botrychium Acuminatum W.H. Wagner
- Tailed Hollyfern - Polystichum Rhizophyllum (Sw.) C. Presl
- Tailed Kittentails - Synthyris Missurica (Raf.) Pennell
- Tailed Kittentails - Synthyris Missurica (Raf.) Pennell ssp. missurica
- Tailed Maidenhair - Adiantum Caudatum L.
- Tailed Nicker - Caesalpinia Caudata (A. Gray) Fisher
- Tailed Strapfern - Campyloneurum Costatum (Kunze) C. Presl
- Taimyr Catchfly - Silene Taimyrensis (Tolm.) Bocquet
- Taino Pisonia - Pisonia Taina Trejo
- Taique - Desfontainia Ruiz & Pav.
- Taique - Desfontainia Spinosa Ruiz & Pav.
- Taiwan Kudzu - Pueraria Montana (Lour.) Merr. var. montana
- Taiwan Maiden Fern - Thelypteris Taiwanensis (C. Chr.) K. Iwats.
- Taiwanese Cheesewood - Pittosporum Pentandrum (Blanco) Merr.
- Taiwanese Photinia - Photinia Serratifolia (Desf.) Kalkm.
- Takakia - Takakia Lepidozioides S. Hattori & Inoue
- Takakia - Takakia S. Hattori & Inoue
- Takeuch's Lipfern - Doryopteris Takeuchii (W.H. Wagner) W.H. Wagner
- Talapoosa Peak Pearpod - Stroganowia Tiehmii Rollins
- Talayote - Cynanchum Racemosum (Jacq.) Jacq.
- Talayote - Cynanchum Racemosum (Jacq.) Jacq. var. unifarium (Scheele) E. Sundell
- Talh - Vachellia Seyal (Delile) P.J.H. Hurter
- Talinopsis - Talinopsis A. Gray
- Talinum Angustissimum (A. Gray) Wooton & Standl.
- Talinum Appalachianum W. Wolf
- Talinum Aurantiacum Engelm.
- Talinum Aurantiacum Engelm. var. angustissimum A. Gray
- Talinum Brevicaule S. Watson
- Talinum Brevifolium Torr.
- Talinum Calcaricum Ware
- Talinum Calycinum Engelm.
- Talinum Chrysanthum Rose & Standl.
- Talinum Confertiflorum Greene
- Talinum Fruticosum (L.) Juss.
- Talinum Humile Greene
- Talinum Longipes Wooton & Standl.
- Talinum Marginatum Greene
- Talinum Mengesii W. Wolf
- Talinum Okanoganense English
- Talinum Paniculatum (Jacq.) Gaertn. var. paniculatum
- Talinum Paniculatum (Jacq.) Gaertn. var. sarmentosum (Engelm.) Poelln.
- Talinum Parviflorum Nutt.
- Talinum Parvulum Rose & Standl.
- Talinum Polygaloides Gillies ex Arn., nom. inq.
- Talinum Pulchellum Wooton & Standl.
- Talinum Pygmaeum A. Gray
- Talinum Reflexum Cav.
- Talinum Rugospermum Holz.
- Talinum Sediforme Poelln.
- Talinum Spathulatum Engelm. ex A. Gray, nom. inq.
- Talinum Spinescens Torr.
- Talinum Teretifolium Pursh
- Talinum Thompsonii N.D. Atwood & S.L. Welsh
- Talinum Validulum Greene
- Talinum Youngiae C.H. Mull.
- Talipariti Tiliaceum (L.) Fryxell
- Talisia Aubl.
- Talisia Pedicellaris Radlk. [excluded]
- Tall Agoseris - Agoseris Elata (Nutt.) Greene
- Tall Albizia - Albizia Procera (Roxb.) Benth.
- Tall Alumroot - Heuchera Chlorantha Piper
- Tall Annual Willowherb - Epilobium Brachycarpum C. Presl
- Tall Baeckea - Baeckea Virgata (J.R. Forst. & G. Forst.) Andrews
- Tall Barbara's Buttons - Marshallia Legrandii Weakley
- Tall Beardgrass - Bothriochloa Alta (Hitchc.) Henr.
- Tall Blacktip Ragwort - Senecio Atratus Greene
- Tall Blazing Star - Liatris Aspera Michx.
- Tall Blazing Star - Liatris Aspera Michx. var. aspera
- Tall Blazing Star - Liatris Aspera Michx. var. intermedia (Lunell) Gaiser
- Tall Blazing Star - Liatris Aspera Michx. var. salutans (Lunell) Shinners
- Tall Blue Lettuce - Lactuca Biennis (Moench) Fernald
- Tall Bluebells - Mertensia Paniculata (Aiton) G. Don
- Tall Bluebells - Mertensia Paniculata (Aiton) G. Don var. paniculata
- Tall Brake - Pteris Altissima Poir.
- Tall Brome - Bromus Grandis (Shear) Hitchc.
- Tall Buckwheat - Eriogonum Tenellum Torr.
- Tall Buckwheat - Eriogonum Tenellum Torr. var. platyphyllum (Torr. ex Benth.) Torr.
- Tall Buckwheat - Eriogonum Tenellum Torr. var. ramosissimum Benth.
- Tall Buckwheat - Eriogonum Tenellum Torr. var. tenellum
- Tall Bugbane - Actaea Elata (Nutt.) Prantl
- Tall Buttercup - Ranunculus Acris L.
- Tall Buttercup - Ranunculus Acris L. var. frigidus Regel
- Tall Chamomile - Anthemis Altissima L.
- Tall Cinquefoil - Potentilla Arguta Pursh
- Tall Cinquefoil - Potentilla Arguta Pursh ssp. arguta
- Tall Coastal Plantain - Plantago Subnuda Pilg.
- Tall Cottongrass - Eriophorum Angustifolium Honck.
- Tall Cottongrass - Eriophorum Angustifolium Honck. ssp. angustifolium
- Tall Cottongrass - Eriophorum Angustifolium Honck. ssp. triste (Th. Fr.) Hultén
- Tall Dodder - Cuscuta Exaltata Engelm.
- Tall Draba - Draba Praealta Greene
- Tall Elephant's Ear - Xanthosoma Undipes (K. Koch) K. Koch
- Tall Elephantsfoot - Elephantopus Elatus Bertol.
- Tall False Foxglove - Agalinis Aspera (Douglas ex Benth.) Britton
- Tall False Hawksbeard - Youngia Thunbergiana DC.
- Tall Fescue - Schedonorus Arundinaceus (Schreb.) Dumort., nom. cons.
- Tall Flatsedge - Cyperus Eragrostis Lam.
- Tall Fleabane - Erigeron Elatior (A. Gray) Greene
- Tall Fringed Bluebells - Mertensia Ciliata (James ex Torr.) G. Don
- Tall Fringed Bluebells - Mertensia Ciliata (James ex Torr.) G. Don var. ciliata
- Tall Fringed Bluebells - Mertensia Ciliata (James ex Torr.) G. Don var. stomatechoides (Kellogg) Jeps.
- Tall Globethistle - Echinops Exaltatus Schrad.
- Tall Grama - Bouteloua Hirsuta Lag. var. pectinata (Featherly) Cory
- Tall Groundsel - Senecio Hydrophiloides Rydb.
- Tall Hairy Agrimony - Agrimonia Gryposepala Wallr.
- Tall Hawkweed - Hieracium Piloselloides Vill.
- Tall Horned Beaksedge - Rhynchospora Macrostachya Torr. ex A. Gray
- Tall Ironweed - Vernonia Angustifolia Michx.
- Tall Ironweed - Vernonia Angustifolia Michx. ssp. angustifolia
- Tall Ironweed - Vernonia Angustifolia Michx. ssp. scaberrima (Nutt.) S.B. Jones & Faust
- Tall Jacob's-ladder - Polemonium Acutiflorum Willd. ex Roem. & Schult.
- Tall Jointweed - Polygonella Gracilis Meisn.
- Tall Ladies'-tresses - Cyclopogon Elatus (Sw.) Schltr.
- Tall Larkspur - Delphinium Exaltatum Aiton
- Tall Lespedeza - Lespedeza Stuevei Nutt.
- Tall Milkvetch - Astragalus Altus Wooton & Standl.
- Tall Morning-glory - Ipomoea Purpurea (L.) Roth
- Tall Mountain Larkspur - Delphinium Scaposum Greene
- Tall Oat Grass - Arrhenatherum Album (Vahl) Clayton
- Tall Oatgrass - Arrhenatherum Elatius (L.) P. Beauv. ex J. Presl & C. Presl
- Tall Oatgrass - Arrhenatherum Elatius (L.) P. Beauv. ex J. Presl & C. Presl var. bulbosum (Willd.) Spe
- Tall Oatgrass - Arrhenatherum Elatius (L.) P. Beauv. ex J. Presl & C. Presl var. elatius
- Tall Phacelia - Phacelia Procera A. Gray
- Tall Pinebarren Milkwort - Polygala Cymosa Walter
- Tall Poppymallow - Callirhoe Leiocarpa R.F. Martin
- Tall Ragwort - Senecio Serra Hook.
- Tall Ragwort - Senecio Serra Hook. var. admirabilis (Greene) A. Nelson
- Tall Ragwort - Senecio Serra Hook. var. serra
- Tall Rattlesnakeroot - Prenanthes Altissima L.
- Tall Reed - Phragmites Karka (Retz.) Trin. ex Steud. [excluded]
- Tall Silky Lupine - Lupinus Elatus I.M. Johnst.
- Tall Silverbush - Argythamnia Mercurialina (Nutt.) Müll. Arg.
- Tall Silverbush - Argythamnia Mercurialina (Nutt.) Müll. Arg. var. mercurialina
- Tall Silverbush - Argythamnia Mercurialina (Nutt.) Müll. Arg. var. pilosissima (Benth.) Shinners
- Tall Skullcap - Scutellaria Altissima L.
- Tall Snapdragon - Sairocarpus Virga (A. Gray) D.A. Sutton
- Tall Spiny Milkvetch - Astragalus Kentrophyta A. Gray var. elatus S. Watson
- Tall Spiritweed - Aegiphila Elata Sw.
- Tall Thimbleweed - Anemone Virginiana L.
- Tall Thimbleweed - Anemone Virginiana L. var. alba (Oakes) Alph. Wood
- Tall Thimbleweed - Anemone Virginiana L. var. cylindroidea B. Boivin
- Tall Thimbleweed - Anemone Virginiana L. var. virginiana
- Tall Thistle - Cirsium Altissimum (L.) Hill
- Tall Thoroughwort - Eupatorium Altissimum L.
- Tall Threeawn - Aristida Patula Chapm. ex Nash
- Tall Tickseed - Coreopsis Tripteris L.
- Tall Tidytips - Layia Hieracioides (DC.) Hook. & Arn.
- Tall Tonguefern - Elaphoglossum Alatum Gaudich.
- Tall Tonguefern - Elaphoglossum Alatum Gaudich. var. alatum
- Tall Tonguefern - Elaphoglossum Alatum Gaudich. var. crassicaule (Copeland) W.R. Anderson & Crosby
- Tall Tonguefern - Elaphoglossum Alatum Gaudich. var. fauriei (Copeland) W.R. Anderson & Crosby
- Tall Tonguefern - Elaphoglossum Alatum Gaudich. var. parvisquamaeum (Skottsb.) W.R. Anderson & Crosby
- Tall Townsend Daisy - Townsendia Eximia A. Gray
- Tall Trisetum - Trisetum Canescens Buckley
- Tall Tumblemustard - Sisymbrium Altissimum L.
- Tall Tutsan - Hypericum ×inodorum Mill.
- Tall Wheatgrass - Thinopyrum Ponticum (Podp.) Z.-W. Liu & R.-C. Wang
- Tall Windmill Grass - Chloris Elata Desv.
- Tall Woolly Buckwheat - Eriogonum Elatum Douglas ex Benth.
- Tall Woolly Buckwheat - Eriogonum Elatum Douglas ex Benth. var. elatum
- Tall Woolly Buckwheat - Eriogonum Elatum Douglas ex Benth. var. villosum Jeps.
- Tall Yellow Sweetclover - Melilotus Altissimus Thuill.
- Tall Yelloweyed Grass - Xyris Platylepis Chapm.
- Tall Yellowtop - Senecio Magnificus F. Muell.
- Tallahassee Hawthorn - Crataegus Consanguinea Beadle
- Tallerack - Eucalyptus Tetragona (R. Br.) F. Muell.
- Tallow Wood - Ximenia Americana L.
- Tallow Wood - Ximenia Americana L. var. americana
- Tallul Campylopus Moss - Campylopus Tallulensis Sull. & Lesq.
- Talquezal - Paspalum Virgatum L.
- Talus Collomia - Collomia Larsenii (A. Gray) Payson
- Talus Fritillary - Fritillaria Falcata (Jeps.) D.E. Beetle
- Talus Slope Bur Cucumber - Sicyos Waimanaloensis H. St. John
- Talus Springparsley - Cymopterus Lapidosus (M.E. Jones) M.E. Jones
- Talus Willowherb - Epilobium Clavatum Trel.
- Talustuft - Lithophila Muscoides Sw.
- Tamala Borbonia (L.) Raf.
- Tamala Humilis (Nash) Small
- Tamala Littoralis (Small) Small
- Tamala Pubescens (Pursh) Small
- Tamalpais Oak - Quercus Parvula Greene var. tamalpaisensis S.K. Langer
- Tamarack - Larix Laricina (Du Roi) K. Koch
- Tamarind Anisomeridium Lichen - Anisomeridium Tamarindi (Fée) R.C. Harris
- Tamarind - Tamarindus Indica L.
- Tamarind - Tamarindus L.
- Tamarisk - Tamarix Dioica Roxb. ex Roth
- Tamarisk - Tamarix L.
- Tamarisk Thuidium Moss - Thuidium Tamariscinum (Hedw.) Schimp.
- Tamarix Articulata Vahl
- Tamarix Juniperina Bunge
- Tamarix Pentandra Pall.
- Tamarix Stricta Boiss.
- Tamarix Tetrandra auct. non Pall.
- Tamarugo - Prosopis Tamarugo F. Philippi
- Tamaulipas Amaranth - Amaranthus Tamaulipensis Henrickson
- Tamonea Guianensis Aubl.
- Tamonea Macrophylla (D. Don) Krasser
- Tamonea Spicata auct. non Sw.
- Tamonea - Tamonea Aubl.
- Tampa Blackberry - Rubus Audax L.H. Bailey
- Tampa Butterfly Orchid - Encyclia Tampensis (Lindl.) Small
- Tampa Mock Vervain - Glandularia Tampensis (Nash) Small
- Tampa Prairie Clover - Dalea Adenopoda (Rydb.) Isely
- Tamujo - Flueggea Tinctoria (L.) G.L. Webster
- Tanacetum Boreale Fisch. ex DC.
- Tanacetum Canum D.C. Eaton
- Tanacetum Capitatum (Nutt.) Torr. & A. Gray
- Tanacetum Cinerariifolium (Trevir.) Sch. Bip.
- Tanacetum Compactum H.M. Hall
- Tanacetum Diversifolium D.C. Eaton
- Tanacetum Douglasii DC.
- Tanacetum Huronense Nutt.
- Tanacetum Huronense Nutt. var. bifarium Fernald
- Tanacetum Huronense Nutt. var. floccosum Raup
- Tanacetum Huronense Nutt. var. johannense Fernald
- Tanacetum Huronense Nutt. var. terrae-novae Fernald
- Tanacetum Nuttallii Torr. & A. Gray
- Tanacetum Potentilloides (A. Gray) A. Gray
- Tanacetum Potentilloides (A. Gray) A. Gray var. nitrophilum Cronquist
- Tanacetum Serotinum (L.) Sch. Bip.
- Tanacetum Simplex A. Nelson
- Tanacetum Suaveolens (Pursh) Hook.
- Tanacetum Vulgare L. var. crispum DC.
- Tangelo - Citrus ×tangelo J.W. Ingram & H.E. Moore
- Tangerine - Citrus Reticulata Blanco
- Tangier Pea - Lathyrus Tingitanus L.
- Tangled Dewberry - Rubus Plexus Fernald
- Tangled Starviolet - Hedyotis Intricata Fosberg
- Tanglehead - Heteropogon Contortus (L.) P. Beauv. ex Roem. & Schult.
- Tanglehead - Heteropogon Pers.
- Tangor - Citrus Nobilis Lour.
- Tanners Canyon Onion - Allium Plummerae S. Watson
- Tanoak - Notholithocarpus Densiflorus (Hook. & Arn.) P.S. Manos, C.H. Cannon, & S.H. Oh
- Tanoak - Notholithocarpus Densiflorus (Hook. & Arn.) P.S. Manos, C.H. Cannon, & S.H. Oh var. densiflor
- Tanoak - Notholithocarpus Densiflorus (Hook. & Arn.) P.S. Manos, C.H. Cannon, & S.H. Oh var. echinoide
- Tanoak - Notholithocarpus P.s. Manos, C.H. Cannon, & S.H. Oh
- Tanseyleaf Tansyaster - Machaeranthera Tanacetifolia (Kunth) Nees
- Tansy Bristle Fern - Trichomanes Pinnatum Hedw.
- Tansy Cinquefoil - Potentilla Bipinnatifida Douglas ex Hook.
- Tansy Dogshade - Limnosciadium Pinnatum (DC.) Mathias & Constance
- Tansy Pepperweed - Lepidium Pinnatisectum (O.E. Schulz) C.L. Hitchc.
- Tansy Rosinweed - Silphium Pinnatifidum Elliott
- Tansy Spectaclepod - Dimorphocarpa Pinnatifida Rollins
- Tansy - Tanacetum L.
- Tansyaster - Machaeranthera Nees
- Tansyaster - Psilactis A. Gray
- Tansyaster - Rayjacksonia R.l. Hartm. & M.A. Lane
- Tansyleaf Evening Primrose - Camissonia Tanacetifolia (Torr. & A. Gray) P.H. Raven
- Tansyleaf Evening Primrose - Camissonia Tanacetifolia (Torr. & A. Gray) P.H. Raven ssp. tanacetifolia
- Tansyleaf Lidpod - Operculina Pinnatifida (Kunth) O'Donell
- Tansyleaf Nightshade - Solanum Pinnatisectum Dunal [excluded]
- Tansymustard - Descurainia Webb & Bethel.
- Taonabo Heptasepala (Krug & Urb.) Britton
- Taonabo Luquillensis (Krug & Urb.) Britton
- Taonabo Pachyphylla (Krug & Urb.) Britton
- Taonabo Peduncularis (DC.) Britton
- Taonabo Stahlii (Krug & Urb.) Britton
- Taonabo Subsessilis Britton
- Taos Penstemon - Penstemon Crandallii A. Nelson ssp. taosensis (D.D. Keck) Kartesz & Gandhi
- Tape Dwarf Polypody - Grammitis Hessii (Maxon) Alain
- Tapeinidium (c. Presl) C. Chr.
- Tapellaria Lichen - Tapellaria Bilimbioides R. Sant.
- Tapellaria Lichen - Tapellaria Epiphylla (Müll. Arg.) R. Sant.
- Tapellaria Lichen - Tapellaria Müll. Arg.
- Tapellaria Lichen - Tapellaria Nana (Fée) R. Sant.
- Tapered Cudweed - Pseudognaphalium Attenuatum (DC.) Anderb.
- Tapered Polypody - Polypodium Attenuatum Humb. & Bonpl. ex Willd.
- Tapered Rosette Grass - Dichanthelium Acuminatum (Sw.) Gould & C.A. Clark
- Tapered Rosette Grass - Dichanthelium Acuminatum (Sw.) Gould & C.A. Clark var. acuminatum
- Taperfruit Shortscale Sedge - Carex Leptopoda Mack.
- Taperleaf Water Horehound - Lycopus Rubellus Moench
- Tapertip Cinquefoil - Potentilla Acuminata H.M. Hall
- Tapertip Cupgrass - Eriochloa Acuminata (J. Presl) Kunth
- Tapertip Cupgrass - Eriochloa Acuminata (J. Presl) Kunth var. acuminata
- Tapertip Cupgrass - Eriochloa Acuminata (J. Presl) Kunth var. minor (Vasey) R.B. Shaw
- Tapertip Desertparsley - Lomatium Attenuatum Evert
- Tapertip Dodder - Cuscuta Attenuata Waterf.
- Tapertip False Wheatgrass - Eremopyrum Bonaepartis (Spreng.) Nevski
- Tapertip Flatsedge - Cyperus Acuminatus Torr. & Hook. ex Torr.
- Tapertip Hawksbeard - Crepis Acuminata Nutt.
- Tapertip Hawksbeard - Crepis Acuminata Nutt. ssp. acuminata
- Tapertip Hawksbeard - Crepis Acuminata Nutt. ssp. pluriflora Babc. & Stebbins
- Tapertip Liveforever - Dudleya Attenuata (S. Watson) Moran
- Tapertip Onion - Allium Acuminatum Hook.
- Tapertip Rush - Juncus Acuminatus Michx.
- Tapertip Smartweed - Polygonum Acuminatum Kunth
- Tapertip Spleenwort - Asplenium Acuminatum Hook. & Arn.
- Tapertip Wakerobin - Trillium Viridescens Nutt.
- Tapeworm-plant - Eubrachion Ambiguum (Hook. & Arn.) Engl.
- Tapeworm-plant - Eubrachion Ambiguum (Hook. & Arn.) Engl. var. jamaicense Krug & Urb.
- Tapeworm-plant - Eubrachion Hook. f.
- Taproot Fleabane - Erigeron Radicatus Hook.
- Tara Vine - Actinidia Arguta (Siebold & Zucc.) Planch. ex Miq.
- Taraktogenos Kurzii King
- Taralea - Taralea Aubl.
- Taraxacum Alaskanum Rydb.
- Taraxacum Ambigens Fernald
- Taraxacum Ambigens Fernald var. flutius Fernald
- Taraxacum Amphiphron Böcher
- Taraxacum Arcticum (Trautv.) Dahlst.
- Taraxacum Arctogenum Dahlst.
- Taraxacum Atroglaucum M.P. Christ.
- Taraxacum Brachyceras Dahlst.
- Taraxacum Campylodes G.E. Haglund
- Taraxacum Carthamopsis A.E. Porsild
- Taraxacum Ceratophorum (Ledeb.) DC.
- Taraxacum Croceum auct. non Dahlst.
- Taraxacum Curvidens M.P. Christ.
- Taraxacum Cyclocentrum M.P. Christ.
- Taraxacum Dahlstedtii Lindb. f.
- Taraxacum Davidssonii M.P. Christ.
- Taraxacum Devians Dahlst.
- Taraxacum Dilutisquameum M.P. Christ.
- Taraxacum Disseminatum G.E. Haglund
- Taraxacum Dumetorum Greene
- Taraxacum Erythrospermum Andrz. ex Besser
- Taraxacum Eurylepium Dahlst.
- Taraxacum Firmum Dahlst.
- Taraxacum Hyparcticum Dahlst.
- Taraxacum Hyperboreum Dahlst.
- Taraxacum Integratum G.E. Haglund
- Taraxacum Islandiciforme Dahlst.
- Taraxacum Kamtschaticum Dahlst.
- Taraxacum Kok-saghyz auct. non Rodin
- Taraxacum Lacerum Greene
- Taraxacum Lacistophyllum (Dahlst.) Raunk.
- Taraxacum Lapponicum Kihlm. ex Hand.-Maz.
- Taraxacum Lateritium Dahlst.
- Taraxacum Latilobum DC., nom. inq.
- Taraxacum Latispinulosum M.P. Christ.
- Taraxacum Laurentianum Fernald
- Taraxacum Longii Fernald
- Taraxacum Mackenziense A.E. Porsild
- Taraxacum Malteanum Dahlst.
- Taraxacum Maurolepium G.E. Haglund
- Taraxacum Mitratum G.E. Haglund
- Taraxacum Multesimum G.E. Haglund
- Taraxacum Naevosum Dahlst.
- Taraxacum Officinale F.H. Wigg. ssp. vulgare (Lam.) Schinz & R. Keller, nom. inq.
- Taraxacum Officinale F.H. Wigg. var. palustre (Lyons) Blytt p.p.
- Taraxacum Olympicum G.N. Jones, nom. inq.
- Taraxacum Ovinum Rydb.
- Taraxacum Palustre (Lyons) Symons var. vulgare (Lam.) Fernald, nom. inq.
- Taraxacum Paucisquamosum M. Peck
- Taraxacum Pellianum A.E. Porsild
- Taraxacum Pleniflorum M.P. Christ.
- Taraxacum Pseudonorvegicum Dahlst.
- Taraxacum Pumilum Dahlst.
- Taraxacum Purpuridens Dahlst.
- Taraxacum Retroflexum Lindb. f.
- Taraxacum Rhodolepis Dahlst.
- Taraxacum Scanicum Dahlst.
- Taraxacum Scopulorum (A. Gray) Rydb.
- Taraxacum Sibiricum Dahlst.
- Taraxacum Torngatense Fernald
- Taraxacum Trigonolobum Dahlst.
- Taraxacum Turfosum (Sch. Bip.) Soest
- Taraxacum Umbrinum Dahlst.
- Taraxacum Undulatum Lindb. f. & Marklund
- Taraxacum Vagans G.E. Haglund
- Taraxacum Vulgare Lam., nom. inq.
- Taraxacum Xanthostigma Lindb. f.
- Taraxia Breviflora (Torr. & A. Gray) Nutt. ex Small
- Taraxia Subacaulis (Pursh) Rydb.
- Taraxia Tanacetifolia (Torr. & A. Gray) Piper
- Tarenaya Hassleriana (Chodat) Iltis
- Tarenaya Spinosa (Jacq.) Raf.
- Tarenna Gaertn.
- Tarenna Sambucina (G. Forst.) Durand
- Targionia Hypophylla L.
- Targionia L.
- Targionia Orbicularis Schwein.
- Tarheel Sedge - Carex Austrocaroliniana L.H. Bailey
- Tarheel Sedge - Carex Pigra Naczi
- Taro - Alocasia (schott) G. Don
- Tarovine - Monstera Deliciosa Liebm.
- Tarragon - Artemisia Dracunculus L.
- Tartary Buckwheat - Fagopyrum Tataricum (L.) Gaertn.
- Tarweed - Anisocarpus Madioides Nutt.
- Tarweed - Anisocarpus Nutt.
- Tarweed - Centromadia Greene
- Tarweed - Deinandra Greene
- Tarweed Fiddleneck - Amsinckia Lycopsoides Lehm.
- Tarweed - Harmonia B.g. Baldw.
- Tarweed - Harmonia Guggolziorum B.G. Baldw.
- Tarweed - Hemizonella (a. Gray) A. Gray
- Tarweed - Hemizonia Dc.
- Tarweed - Holocarpha Greene
- Tarweed - Jensia B.g. Baldw.
- Tarweed - Madia Molina
- Tarwi - Lupinus Mutabilis Sweet
- Tarwort - Flourensia Dc.
- Tasmanian Bluegum - Eucalyptus Globulus Labill.
- Tasmanian Bluegum - Eucalyptus Globulus Labill. ssp. globulus
- Tasmanian Bluegum - Eucalyptus Globulus Labill. ssp. maidenii (F. Muell.) J.B. Kirkpat.
- Tasmanian Wallaby Grass - Rytidosperma Semiannulare (Labill.) Connor & Edgar
- Tasmanian Xanthoparmelia Lichen - Xanthoparmelia Tasmanica (Hook. f. & Taylor) Hale
- Tassel Fern - Huperzia Phlegmaria (L.) Rothm.
- Tassel Grape Hyacinth - Muscari Comosum (L.) Mill.
- Tasselflower Brickellbush - Brickellia Grandiflora (Hook.) Nutt.
- Tasselflower - Emilia Cass.
- Tasteless Stonecrop - Sedum Sexangulare L.
- Tatarian Aster - Aster Tataricus L. f.
- Tatarian Cephalaria - Cephalaria Gigantea (Ledeb.) Bobr.
- Tatarian Honeysuckle - Lonicera Tatarica L.
- Tatarian Maple - Acer Tataricum L.
- Tatarian Orache - Atriplex Tatarica L.
- Tausch's Goatgrass - Aegilops Tauschii Coss.
- Tavares' Matted Lichen - Pannaria Tavaresii P.M. Jørg.
- Taw Manroot - Marah Watsonii (Cogn.) Greene
- Tawhiwhi - Pittosporum Tenuifolium Gaertn.
- Tawny Cottongrass - Eriophorum Virginicum L.
- Tawny Cryptantha - Cryptantha Fulvocanescens (S. Watson) Payson
- Tawny Cryptantha - Cryptantha Fulvocanescens (S. Watson) Payson var. fulvocanescens
- Tawny Cryptantha - Cryptantha Fulvocanescens (S. Watson) Payson var. nitida (Greene) R.C. Sivinski
- Tawny Pea - Pisum Fulvum Sm.
- Tawnyberry Holly - Ilex Krugiana Loes.
- Taxilejeunea (spruce) Schiffn.
- Taxilejeunea Obtusangula (Spruce) A. Evans
- Taxiphyllum Andersonii (E.B. Bartram) H.A. Crum
- Taxiphyllum Geophilum (Austin) Fleisch.
- Taxiphyllum Howellianum H.A. Crum & L.E. Anderson
- Taxiphyllum Mariannae (Grout) Schornh.
- Taxiphyllum Moss - Taxiphyllum Alternans (Cardot) Z. Iwats.
- Taxiphyllum Moss - Taxiphyllum Deplanatum (Bruch & Schimp. ex Sull.) Fleisch.
- Taxiphyllum Moss - Taxiphyllum Fleisch.
- Taxiphyllum Moss - Taxiphyllum Taxirameum (Mitt.) Fleisch.
- Taxiphyllum Planissimum (Mitt.) Broth.
- Taxiphyllum Sharpii (H.A. Crum & L.E. Anderson) H. Rob.
- Taxiphyllum Squamatum (Broth.) Z. Iwats.
- Taxithelium Moss - Taxithelium Planum (Brid.) Mitt.
- Taxithelium Moss - Taxithelium Spruce ex Mitt.
- Taxodium Distichum (L.) Rich. var. imbricarium (Nutt.) Croom
- Taxodium Distichum (L.) Rich. var. mexicanum (Carrière) Gordon
- Taxodium Distichum (L.) Rich. var. mucronatum (Ten.) A. Henry
- Taxodium Distichum (L.) Rich. var. nutans (Aiton) Sweet
- Taxus Baccata L. var. aurea Carrière
- Taxus Baccata L. var. fastigiata (Lindl.) Loudon
- Taxus Baccata L. var. fastigiata-aurea Seneclauze
- Taxus Baccata L. var. washingtonii (R. Sm.) Beissn.
- Taxus Canadensis Marshall ssp. floridana (Nutt. ex Chapm.) Silba
- Taxus Canadensis Marshall var. adpressa (Carrière) Spjut
- Taxus Canadensis Marshall var. minor (Michx.) Spjut
- Taxus Globosa Schltdl. var. floridana (Nutt. ex Chapm.) Spjut
- Taylor County Blackberry - Rubus Tygartensis H.A. Davis & T. Davis
- Taylor County Goldaster - Pityopsis Pinifolia (Elliott) Nutt.
- Taylor's Fawnlily - Erythronium Taylorii Shevock & Allen
- Taylor's Filmy Fern - Hymenophyllum Tayloriae Farrar & Raine
- Taylor's Jujube - Ziziphus Taylorii (Britton) M.C. Johnst.
- Taylor's Quillwort - Isoetes ×carltaylorii Musselman
- Taylor's Saxifrage - Saxifraga Taylori Calder & Savile
- Tayloria Dung Moss - Tayloria Hook.
- Tayloria Hornschuchiana (Grev. & Arn.) Broth.
- Tayloria Serrata (Hedw.) Bruch & Schimp. var. flagellaris (Brid.) Bruch & Schimp.
- Tayloria Serrata (Hedw.) Bruch & Schimp. var. tenuis (With.) Bruch & Schimp.
- Tayloria Splachnoides (Schleich. ex Schwägr.) Hook. var. acuminata (Hornsch.) Hüb.
- Tayloria Tenuis (With.) Schimp.
- Te - Ilex Cookii Britton & P. Wilson
- Tea - Camellia Sinensis (L.) Kuntze
- Tea - Camellia Sinensis (L.) Kuntze var. sinensis
- Tea Rose - Rosa ×odorata (Andrews) Sweet (pro sp.)
- Tea Viburnum - Viburnum Setigerum Hance
- Teabush - Melochia Tomentosa L.
- Teak - Tectona Grandis L. f.
- Teal Lovegrass - Eragrostis Hypnoides (Lam.) Britton, Sterns & Poggenb.
- Tealeaf Willow - Salix Pulchra Cham.
- Tearshrub - Vallesia Antillana Woodson
- Teasel Clover - Trifolium Retusum L.
- Teasel - Dipsacus L.
- Teatree - Leptospermum J.r. Forst. & G. Forst.
- Tecate Cypress - Hesperocyparis Forbesii (Jeps.) Bartel
- Tecate Tarweed - Hemizonia Floribunda A. Gray
- Tecoma Gaudichaudii DC.
- Tecoma Radicans (L.) Juss.
- Tecoma Ricasoliana Tanfani
- Tecoma Stans (L.) Juss. ex Kunth var. angustatum Rehder
- Tecomanthe Dendrophila (Blume) K. Schum.
- Tecomanthe - Tecomanthe Baill.
- Tecomaria Capensis (Thunb.) Spach
- Tecopa Bird's Beak - Cordylanthus Tecopensis Munz & Roos
- Tectaria Crenata Cav.
- Tectaria Lobata (C. Presl) Morton
- Tectaria Martinicensis (Spreng.) Copeland
- Tectaria Minima Underw.
- Tectona - Tectona L. f.
- Ted's Lecidea Lichen - Lecidea Theodori Lynge
- Teddybear Cholla - Cylindropuntia Bigelovii (Engelm.) F.M. Knuth
- Teff - Eragrostis Tef (Zuccagni) Trotter
- Tehachapi Linanthus - Leptosiphon Nudatus (Greene) J.M. Porter & L.A. Johnson
- Tehachapi Ragwort - Packera Ionophylla (Greene) W.A. Weber & Á. Löve
- Tehachapi Rose - Rosa Woodsii Lindl. var. gratissima (Greene) Cole
- Tehachapi Woollystar - Eriastrum Pluriflorum (A. Heller) H. Mason
- Tehachapi Woollystar - Eriastrum Pluriflorum (A. Heller) H. Mason ssp. pluriflorum
- Tehama Copper Moss - Mielichhoferia Tehamensis Showers
- Tehama Pincushionplant - Navarretia Heterandra H. Mason
- Tehipite Valley Jewelflower - Streptanthus Fenestratus (Greene) J.T. Howell
- Tejon Cryptantha - Cryptantha Microstachys (Greene ex A. Gray) Greene
- Tejon Poppy - Eschscholzia Lemmonii Greene ssp. kernensis (Munz) C. Clark
- Teketekel - Medinilla Blumeana Mansf.
- Telaranea Nematodes (Gottsche ex Austin) M. Howe
- Telaranea Spruce ex Schiffn.
- Telegraph-plant - Codariocalyx Motorius (Houtt.) H. Ohashi
- Telegraphweed - Heterotheca Grandiflora Nutt.
- Telephus Spurge - Euphorbia Telephioides Chapm.
- Telescope Peak Buckwheat - Eriogonum Eremicola J.T. Howell & Reveal
- Telesonix Jamesii (Torr.) Raf. var. heucheriformis (Rydb.) Bacig.
- Telfairia - Telfairia Hook.
- Teline Canariensis (L.) Webb & Bethel.
- Teline Linifolia (L.) Webb & Bethel.
- Teline Monspessulana (L.) K. Koch
- Teliostachya - Teliostachya Nees
- Tellicherry Bark - Holarrhena Antidysenterica (Roxb. ex Fleming) Wall. ex A. DC.
- Tellima Odorata Howell
- Tellima - Tellima R. Br.
- Teloschistes Californicus Sipman
- Teloschistes Candelaris (L.) Fink
- Teloschistes Euplocus (Tuck.) Zahlbr.
- Teloschistes Lichen - Teloschistes Chrysophthalmus (L.) Th. Fr.
- Teloschistes Lichen - Teloschistes Contortuplicatus (Ach.) Clauzade & Rondon ex Vezda
- Teloschistes Lichen - Teloschistes Exilis (Michx.) Vain.
- Teloschistes Lichen - Teloschistes Flavicans (Sw.) Norman
- Teloschistes Lichen - Teloschistes Norman
- Teloschistes Parietinus (L.) Norman
- Teloschistes Polycarpus (Hoffm.) Tuck.
- Teloschistes Ramulosus Tuck.
- Teloschistes Villosus auct.
- Telosiphonia Brachysiphon (Torr.) Henrickson
- Telosiphonia Hypoleuca (Benth.) Henrickson
- Telosiphonia Lanuginosa (M. Martens & Galeotti) Henrickson
- Telosiphonia Macrosiphon (Torr.) Henrickson
- Telosma Cordata (Burm. f.) Merr.
- Telosma - Telosma Coville
- Teloxys Ambrosioides (L.) W.A. Weber
- Teloxys Aristata (L.) Moq.
- Teloxys Botrys (L.) W.A. Weber
- Teloxys Graveolens (Willd.) W.A. Weber
- Teloxys Multifida (L.) W.A. Weber
- Teloxys Pumilio (R. Br.) W.A. Weber
- Teloxys Schraderiana (Schult.) W.A. Weber
- Teloxys Vagans (Standl.) W.A. Weber
- Tembien Clover - Trifolium Tembense Fresen.
- Temblor Buckwheat - Eriogonum Temblorense J.T. Howell & Twisselmann
- Temblor Range Clarkia - Clarkia Tembloriensis Vasek
- Temblor Range Clarkia - Clarkia Tembloriensis Vasek ssp. tembloriensis
- Temple Juniper - Juniperus Rigida Siebold & Zucc. [excluded]
- Templetree - Plumeria Rubra L.
- Tenangle Pipewort - Eriocaulon Decangulare L.
- Tenangle Pipewort - Eriocaulon Decangulare L. var. decangulare
- Tenangle Pipewort - Eriocaulon Decangulare L. var. latifolium Chapm.
- Tender Green - Brassica Perviridis (L.H. Bailey) L.H. Bailey
- Tender Lovegrass - Eragrostis Scaligera Salzm. ex Steud.
- Tenerife White Marguerite - Argyranthemum Gracilis Webb ex Sch. Bip.
- Tenfinger Menodora - Menodora Decemfida (Gillies ex Hook. & Arn.) A. Gray
- Tenfinger Menodora - Menodora Decemfida (Gillies ex Hook. & Arn.) A. Gray var. longifolia Steyerm.
- Tenleaf Woodsorrel - Oxalis Decaphylla Kunth
- Tenlobe False Foxglove - Agalinis Obtusifolia Raf.
- Tennessee Bladderfern - Cystopteris Tennesseensis Shaver
- Tennessee Gladecress - Leavenworthia Exigua Rollins
- Tennessee Gladecress - Leavenworthia Exigua Rollins var. exigua
- Tennessee Gladecress - Leavenworthia Exigua Rollins var. laciniata Rollins
- Tennessee Gladecress - Leavenworthia Exigua Rollins var. lutea Rollins
- Tennessee Ironweed - Vernonia Flaccidifolia Small
- Tennessee Leafcup - Polymnia Laevigata Beadle
- Tennessee Milkvetch - Astragalus Tennesseensis A. Gray ex Chapm.
- Tennessee Pondweed - Potamogeton Tennesseensis Fernald
- Tennessee Purple Coneflower - Echinacea Tennesseensis (Beadle) Small
- Tennessee Quillwort - Isoetes Tennesseensis Luebke & Budke
- Tennessee Snow Lichen - Stereocaulon Tennesseense H. Magn. ex Degel.
- Tennessee Starwort - Stellaria Corei Shinners
- Tennessee Yelloweyed Grass - Xyris Tennesseensis Kral
- Tenpetal Blazingstar - Mentzelia Decapetala (Pursh ex Sims) Urb. & Gilg ex Gilg
- Tenpetal Thimbleweed - Anemone Berlandieri Pritz.
- Tenterfield Woollybutt - Eucalyptus Banksii Maiden
- Tenweeks Stock - Matthiola Incana (L.) W.T. Aiton
- Teosinte - Zea Luxurians (Durieu & Asch.) Bird
- Tepary Bean - Phaseolus Acutifolius A. Gray
- Tepary Bean - Phaseolus Acutifolius A. Gray var. acutifolius
- Tepary Bean - Phaseolus Acutifolius A. Gray var. latifolius Freeman
- Tepary Bean - Phaseolus Acutifolius A. Gray var. tenuifolius A. Gray
- Tephromela Aglaeida Nyl., nom. inq.
- Tephromela Lichen - Tephromela Aglaea (Sommerf.) Hertel & Rambold
- Tephromela Lichen - Tephromela Atra (Huds.) Hafellner
- Tephromela Lichen - Tephromela M. Choisy
- Tephromela Lichen - Tephromela Testaceoatra (Vain.) Hertel & Rambold
- Tephroseris Atropurpurea (Ledeb.) Holub ssp. tomentosa (Kjellm.) Á. Löve & D. Löve
- Tephroseris Frigida (Richardson) Holub
- Tephroseris Integrifolia (L.) Holub ssp. atropurpurea (Ledeb.) B. Nord.
- Tephroseris Palustris (L.) Rchb.
- Tephroseris Tundricola (Tolm.) Holub var. lindstroemii (Ostenf.) V. Yu.
- Tephrosia Affinis S. Watson
- Tephrosia Ambigua (M.A. Curtis) Kuntze
- Tephrosia Ambigua (M.A. Curtis) Kuntze var. gracillima B.L. Rob.
- Tephrosia Angustifolia Featherm.
- Tephrosia Caribaea (Jacq.) DC.
- Tephrosia Carpenteri (Rydb.) Killip
- Tephrosia Cathartica (Sessé & Moc.) Urb.
- Tephrosia Constricta S. Watson
- Tephrosia Corallicola (Small) Léon
- Tephrosia Curtissii (Small ex Rydb.) Shinners
- Tephrosia Elegans Nutt.
- Tephrosia Flexuosa (Vail) Chapm.
- Tephrosia Florida (F.G. Dietr.) C.E. Wood var. gracillima (B.L. Rob.) Shinners
- Tephrosia Incana (Roxb.) Graham ex Wight & Arn.
- Tephrosia Intermedia auct. non Graham
- Tephrosia Latidens (Small) Standl.
- Tephrosia Multiflora Featherm.
- Tephrosia Nitens Benth. ex Seem.
- Tephrosia Oxygona Welw. ex Baker
- Tephrosia Piscatoria (Dryand.) Pers.
- Tephrosia Purpurea auct. non (L.) Pers.
- Tephrosia Richardsiae J.B. Gillett
- Tephrosia Seminole Shinners
- Tephrosia Spicata (Walter) Torr. & A. Gray var. semitonsa Fernald
- Tephrosia Subtriflora Hochst. ex Baker
- Tephrosia Tenella A. Gray
- Tephrosia Texana (Rydb.) Cory
- Tephrosia Toxicaria (Sw.) Pers.
- Tephrosia Vestita Vogel
- Tephrosia Villosa (L.) Pers.
- Tephrosia Villosa (L.) Pers. ssp. villosa
- Tephrosia Virginiana (L.) Pers. var. glabra Nutt.
- Tephrosia Virginiana (L.) Pers. var. holosericea (Nutt.) Torr. & A. Gray
- Tephrosia Viridis M.E. Jones
- Tepic Flameflower - Phemeranthus Parvulus (Rose & Standl.) D.J. Ferguson & T.M. Price
- Tepion Alatum (L.) Britton
- Tequila Agave - Agave Tequilana F.A.C Weber
- Teramnus Repens (Taub.) Baker f.
- Teramnus - Teramnus P. Br.
- Teramnus Volubilis Sw.
- Terania Frutescens Berl.
- Terebraria Resinosa (Vahl) Sprague
- Terete Skin Lichen - Leptogium Teretiusculum (Wallr.) Arnold
- Terlingua Brickellia - Brickellia Hinckleyi Standl. var. terlinguensis (Flyr) B.L. Turner
- Terlingua Creek Cryptantha - Cryptantha Crassipes I.M. Johnst.
- Terlingua Sandmat - Chamaesyce Theriaca (L.C. Wheeler) Shinners
- Terminalia Samoensis Rech.
- Terminalia - Terminalia Carolinensis Kaneh.
- Ternate Buckwheat - Eriogonum Ternatum Howell
- Ternate Grapefern - Botrychium Rugulosum W.H. Wagner
- Ternstroemia Albopunctata Griseb.
- Ternstroemia - Ternstroemia Mutis ex L. f.
- Terra Alta Blackberry - Rubus Prestonensis H.A. Davis & T. Davis
- Terrellia Villosa (Muhl. ex Willd.) Baum
- Terrelymus Maltei (Bowden) Baum
- Terrestrial Cowhorn Orchid - Cyrtopodium Polyphyllum (Vell.) Pabst ex Barrios
- Terrestrial Water-starwort - Callitriche Terrestris Raf.
- Tessaria Sericea (Nutt.) Shinners
- Tesseranthium Angustifolium (Rydb.) Rydb.
- Tesseranthium Macrophyllum (Greene) Rydb.
- Tesseranthium Radiatum Kellogg
- Teta De Burra Cinarron - Hirtella Rugosa Thuill. ex Pers.
- Teta Prieta - Cleyera Albopunctata (Griseb.) Krug & Urb.
- Teton Lupine - Lupinus Wyethii S. Watson ssp. tetonensis (E.E. Nelson) Cox & D. Dunn
- Teton Wirelettuce - Stephanomeria Fluminea Gottlieb
- Tetracarpidium - Tetracarpidium Conophorum (Müll. Arg.) Hutch. & Dalziel
- Tetracarpidium - Tetracarpidium Pax
- Tetrachne Nees
- Tetraclea Coulteri A. Gray var. angustifolia (Wooton & Standl.) A. Nelson & J.F. Ma
- Tetraclea - Tetraclea A. Gray
- Tetraclea Viscida Lundell
- Tetraclinis - Tetraclinis Masters
- Tetracoccus Fasciculatus (S. Watson) Croizat var. hallii (Brandegee) Dressler
- Tetracoccus Fasciculatus auct. non (S. Watson) Croizat
- Tetradium - Tetradium Lour.
- Tetradymia Canescens DC. var. inermis (Rydb.) Payson
- Tetradymia Comosa A. Gray ssp. tetrameres S.F. Blake
- Tetradymia Ramosissima Torr.
- Tetradymia Spinosa Hook. & Arn. var. longispina M.E. Jones
- Tetragamestus Modestus Rchb. f.
- Tetragastris - Tetragastris Gaertn.
- Tetragonia Expansa Murray
- Tetragonia - Tetragonia L.
- Tetragonolobus Palaestinus Boiss. & Blanche
- Tetragonolobus Requienii (Mauri ex Sanguin.) Sanguin.
- Tetragonolobus Siliquosus Roth
- Tetragonolobus - Tetragonolobus Scop.
- Tetralophozia (r.m. Schust.) Schljakov
- Tetralophozia Filiformis (Steph.) Urmi
- Tetralophozia Setiformis (Ehrh.) Schljakov
- Tetramerium Hispidum Nees
- Tetramerium Nervosum Nees var. hispidum (Nees) Torr.
- Tetramerium Platystegium Torr.
- Tetramerium - Tetramerium Nees
- Tetramicra Elegans (Ham.) Cogn.
- Tetramolopium Arbusculum (A. Gray) Sherff
- Tetramolopium Arenarium (A. Gray) Hillebr. var. dentatum Hillebr.
- Tetramolopium Calcisabulorum (H. St. John) H. St. John
- Tetramolopium Conyzoides (A. Gray) Hillebr. var. dentatum (H. Mann) Sherff
- Tetramolopium Humile (A. Gray) Hillebr. var. skottsbergii Sherff
- Tetramolopium Lepidotum (Less.) Sherff var. luxurians (Hillebr.) Sherff
- Tetramolopium Polyphyllum Sherff
- Tetramolopium - Tetramolopium Nees
- Tetraneuris Brevifolia Greene
- Tetraneuris Depressa (Torr. & A. Gray ex A. Gray) Greene
- Tetraneuris Epunctata A. Nelson
- Tetraneuris Fastigiata Greene
- Tetraneuris Glabra (Nutt.) Greene
- Tetraneuris Mancosensis A. Nelson
- Tetraneuris Pilosa Cockerell
- Tetraneuris Simplex A. Nelson
- Tetraneuris Stenophylla Rydb.
- Tetranthera Californica Hook. & Arn.
- Tetrapanax Papyriferus (Hook.) K. Koch, orth. var.
- Tetrapanax - Tetrapanax (k. Koch) K. Koch
- Tetraphis Browniana (Funck) Hampe var. repanda (Funck) Hampe
- Tetraphis Brownianum (Dicks.) Grev.
- Tetraphis Moss - Tetraphis Geniculata Girg. ex Milde
- Tetraphis Moss - Tetraphis Hedw.
- Tetraphis Moss - Tetraphis Pellucida Hedw.
- Tetraplasandra Bisattenuata Sherff
- Tetraplasandra Gymnocarpa (Hillebr.) Sherff var. leptocarpa Sherff
- Tetraplasandra Gymnocarpa (Hillebr.) Sherff var. megalocarpa Sherff
- Tetraplasandra Gymnocarpa (Hillebr.) Sherff var. pupukeensis (O. Deg.) Sherff
- Tetraplasandra Hawaiensis A. Gray var. awiniensis Sherff
- Tetraplasandra Hawaiensis A. Gray var. gracilis Sherff
- Tetraplasandra Hawaiensis A. Gray var. microcarpa Sherff
- Tetraplasandra Kaalae (Hillebr.) Harms
- Tetraplasandra Kaalae (Hillebr.) Harms var. multiplex Sherff
- Tetraplasandra Kahanana O. Deg. & Sherff
- Tetraplasandra Kavaiensis (H. Mann) Sherff var. dipyrena (H. Mann) Sherff
- Tetraplasandra Kavaiensis (H. Mann) Sherff var. grandis Sherff
- Tetraplasandra Kavaiensis (H. Mann) Sherff var. intercedens Sherff
- Tetraplasandra Kavaiensis (H. Mann) Sherff var. koloana Sherff
- Tetraplasandra Kavaiensis (H. Mann) Sherff var. nahikuensis Sherff
- Tetraplasandra Kavaiensis (H. Mann) Sherff var. occidua O. Deg. & Sherff
- Tetraplasandra Kavaiensis (H. Mann) Sherff var. robustior Sherff
- Tetraplasandra Kohalae Skottsb.
- Tetraplasandra Lanaiensis Rock
- Tetraplasandra Lihuensis Sherff
- Tetraplasandra Lihuensis Sherff var. gracilipes Sherff
- Tetraplasandra Lydgatei (Hillebr.) Harms
- Tetraplasandra Lydgatei (Hillebr.) Harms var. brachypoda Sherff
- Tetraplasandra Lydgatei (Hillebr.) Harms var. coriacea Sherff
- Tetraplasandra Lydgatei (Hillebr.) Harms var. forbesii Sherff
- Tetraplasandra Lydgatei (Hillebr.) Harms var. leptorachis O. Deg. & Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms
- Tetraplasandra Meiandra (Hillebr.) Harms var. bisobtusa Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. bryanii Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. degeneri Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. hillebrandii Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. hiloensis Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. leptomera Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. longipedunculata Skottsb.
- Tetraplasandra Meiandra (Hillebr.) Harms var. makalehana Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. mauiensis Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. molokaiensis Skottsb.
- Tetraplasandra Meiandra (Hillebr.) Harms var. occidentalis Skottsb.
- Tetraplasandra Meiandra (Hillebr.) Harms var. olowaluana Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. ovalis Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. polyantha Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. polystigmata Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. prolifica Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. prolificoides Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. ramosior Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. rhynchocarpa Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. rhynchocarpoides O. Deg. & Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. rockii Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. simulans Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. skottsbergii Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. tenuistylis Sherff
- Tetraplasandra Meiandra (Hillebr.) Harms var. tenuistyloides O. Deg. & Sherff
- Tetraplasandra Micrantha Sherff
- Tetraplasandra Munroi Sherff
- Tetraplasandra Oahuensis (A. Gray) Harms var. eradiata Sherff
- Tetraplasandra Oahuensis (A. Gray) Harms var. fauriei Sherff
- Tetraplasandra Oahuensis (A. Gray) Harms var. hailiensis (O. Deg. & Sherff) O. Deg. & She
- Tetraplasandra Oahuensis (A. Gray) Harms var. longipes Sherff
- Tetraplasandra Oahuensis (A. Gray) Harms var. pseudolongipes O. Deg. & Sherff
- Tetraplasandra Oahuensis (A. Gray) Harms var. pseudorachis Sherff
- Tetraplasandra Oahuensis (A. Gray) Harms var. subglobosa O. Deg., I. Deg. & Sherff
- Tetraplasandra Oahuensis (A. Gray) Harms var. venulosior Sherff
- Tetraplasandra Pupukeensis Skottsb.
- Tetraplasandra Pupukeensis Skottsb. var. decipiens O. Deg. & Sherff
- Tetraplasandra Pupukeensis Skottsb. var. megalopoda Sherff
- Tetraplasandra Pupukeensis Skottsb. var. nitida O. Deg. & Sherff
- Tetraplasandra Pupukeensis Skottsb. var. venosa O. Deg. & Sherff
- Tetraplasandra Sherffii O. Deg. & I. Deg.
- Tetraplasandra - Tetraplasandra A. Gray
- Tetraplasandra Turbens Sherff
- Tetraplasandra Waialealae Rock var. acrior Sherff
- Tetraplasandra Waialealae Rock var. kohuana O. Deg. & Sherff
- Tetraplasandra Waialealae Rock var. pluricostata O. Deg. & Sherff
- Tetraplasandra Waialealae Rock var. subsessilis Sherff
- Tetraplasandra Waialealae Rock var. urceolata Sherff
- Tetraplasandra Waialealae Rock var. wahiawensis Sherff
- Tetraplasandra Waianuensis O. Deg.
- Tetraplasandra Waianuensis O. Deg. var. palehuana Sherff
- Tetraplasandra Waimeae Wawra var. angustior Sherff
- Tetraplodon Mnioides (Hedw.) Bruch & Schimp. ssp. pallidus (I. Hagen) Kindb.
- Tetraplodon Mnioides (Hedw.) Bruch & Schimp. var. brewerianus (Hedw.) Bruch & Schimp.
- Tetraplodon Mnioides (Hedw.) Bruch & Schimp. var. cavifolius Schimp.
- Tetraplodon Mnioides (Hedw.) Bruch & Schimp. var. paradoxus (R. Br.) C.E.O. Jensen
- Tetraplodon Mnioides (Hedw.) Bruch & Schimp. var. urceolatus (Hedw.) Steere
- Tetraplodon Pennsylvanicum (Brid.) Sayre
- Tetrapogon Desf.
- Tetrapogon Mossambicensis (K. Schum.) Chippind. ex B.S. Fisher
- Tetrapogon Villosum Desf., orth. var.
- Tetrapogon Villosus Desf.
- Tetrapterys Citrifolia auct. non (Sw.) Pers.
- Tetrapterys - Tetrapterys Cav.
- Tetrastigma - Tetrastigma (miq.) Planch.
- Tetrazygia Stahlii Cogn.
- Tetrodontium Brownianum (Dicks.) Schwägr. var. ovatum (Funck) Wijk & Margad.
- Tetrodontium Moss - Tetrodontium Repandum (Funck) Schwägr.
- Tetrodontium Moss - Tetrodontium Schwägr.
- Tetrorum Pusillum (Michx.) Rose
- Teucrium Boreale E.P. Bicknell
- Teucrium Canadense L. ssp. occidentale (A. Gray) W.A. Weber
- Teucrium Canadense L. ssp. viscidum (Piper) Roy L. Taylor & MacBryde p.p.
- Teucrium Canadense L. var. angustatum A. Gray
- Teucrium Canadense L. var. boreale (E.P. Bicknell) Shinners
- Teucrium Canadense L. var. littorale (E.P. Bicknell) Fernald
- Teucrium Canadense L. var. nashii (Kearney) Shinners
- Teucrium Canadense L. var. virginicum (L.) Eaton
- Teucrium Cubense Jacq. ssp. depressum (Small) E.M. McClint. & Epling
- Teucrium Cubense Jacq. ssp. laevigatum (Vahl) E.M. McClint. & Epling
- Teucrium Depressum Small
- Teucrium Littorale E.P. Bicknell
- Teucrium Nashii Kearney
- Teucrium Occidentale A. Gray
- Teucrium Occidentale A. Gray var. boreale (E.P. Bicknell) Fernald
- Tex-mex Tobacco - Nicotiana Plumbaginifolia Viv.
- Texan Avens - Geum Canadense Jacq. var. texanum Fernald & Weath.
- Texan Candyleaf - Stevia Ovata Willd. var. texana Grashoff
- Texan Canoparmelia Lichen - Canoparmelia Texana (Tuck.) Elix & Hale
- Texan Flatsedge - Cyperus Polystachyos Rottb. var. texensis (Torr.) Fernald
- Texan Fumewort - Corydalis Micrantha (Engelm. ex A. Gray) A. Gray ssp. texensis G.B. Ownbey
- Texan Goatbush - Castela Erecta Turp. ssp. texana (Torr. & A. Gray) Cronquist
- Texan Great Ragweed - Ambrosia Trifida L. var. texana Scheele
- Texan Groundcherry - Physalis Virginiana Mill. var. texana (Rydb.) Waterf.
- Texan Gumweed - Grindelia Lanceolata Nutt. var. texana (Scheele) Shinners
- Texan Hogplum - Colubrina Texensis (Torr. & A. Gray) A. Gray
- Texan Hogplum - Colubrina Texensis (Torr. & A. Gray) A. Gray var. pedunculata M.C. Johnst.
- Texan Hogplum - Colubrina Texensis (Torr. & A. Gray) A. Gray var. texensis
- Texan Horsenettle - Solanum Fendleri A. Gray ex Torr. var. texense Correll
- Texan Phacelia - Phacelia Integrifolia Torr. var. texana (J. Voss) N.D. Atwood
- Texan Phlox - Phlox Nivalis Lodd. ex Sweet ssp. texensis Lundell
- Texan Pore Lichen - Pertusaria Texana Müll. Arg.
- Texan Sugarberry - Celtis Laevigata Willd. var. texana Sarg.
- Texan Syrrhopodon Moss - Syrrhopodon Texanus Sull.
- Texas Almond - Prunus Minutiflora Engelm.
- Texas Ash - Fraxinus Albicans Buckley
- Texas Aster - Symphyotrichum Eulae (Shinners) G.L. Nesom
- Texas Azalea - Rhododendron Oblongifolium (Small) Millais
- Texas Babybonnets - Coursetia Axillaris J.M. Coult. & Rose
- Texas Barberry - Mahonia Swaseyi (Buckley ex Young) Fedde
- Texas Barometer Bush - Leucophyllum Frutescens (Berl.) I.M. Johnst.
- Texas Bedstraw - Galium Texense A. Gray
- Texas Beeblossom - Oenothera Calcicola (P.H. Raven & D.P. Greg.) W.L. Wagner & Hoch
- Texas Bergia - Bergia Texana (Hook.) Seub. ex Walp.
- Texas Bindweed - Convolvulus Equitans Benth.
- Texas Bittercress - Cardamine Macrocarpa Brandegee var. texana Rollins
- Texas Blacksenna - Seymeria Texana (A. Gray) Pennell
- Texas Blazingstar - Mentzelia Texana Urb. & Gilg
- Texas Bluebonnet - Lupinus Subcarnosus Hook.
- Texas Bluegrass - Poa Arachnifera Torr.
- Texas Bluestar - Amsonia Ciliata Walter var. texana (A. Gray) J.M. Coult.
- Texas Bluestem - Schizachyrium Cirratum (Hack.) Wooton & Standl.
- Texas Blueweed - Helianthus Ciliaris DC.
- Texas Bristlegrass - Setaria Texana W.H.P. Emery
- Texas Bristleleaf - Thymophylla Tenuiloba (DC.) Small var. texana (Cory) Strother
- Texas Brome - Bromus Texensis (Shear) Hitchc.
- Texas Broomweed - Amphiachyris Amoena (Shinners) Solbrig
- Texas Bruchia Moss - Bruchia Texana Austin
- Texas Bullnettle - Cnidoscolus Texanus (Müll. Arg.) Small
- Texas Burstwort - Hermannia Texana A. Gray
- Texas Chickweed - Cerastium Texanum Britton
- Texas Chrysopsis - Chrysopsis Texana G.L. Nesom
- Texas Coneflower - Rudbeckia Texana (Perdue) P. Cox & Urbatsch
- Texas Cornsalad - Valerianella Florifera Shinners
- Texas Cottontop - Digitaria Patens (Swallen) Henr.
- Texas Crab Apple - Malus Ioensis (Alph. Wood) Britton var. texana Rehder
- Texas Crabgrass - Digitaria Texana Hitchc.
- Texas Craglily - Echeandia Texensis Cruden
- Texas Crested Coralroot - Hexalectris Warnockii Ames & Correll
- Texas Crinklemat - Tiquilia Gossypina (Wooton & Standl.) A.T. Richardson
- Texas Croton - Croton Texensis (Klotzsch) Müll. Arg.
- Texas Croton - Croton Texensis (Klotzsch) Müll. Arg. var. texensis
- Texas Crownbeard - Verbesina Microptera DC.
- Texas Cupflower - Hunzikeria Texana (Torr.) D'Arcy
- Texas Cupgrass - Eriochloa Sericea (Scheele) Munro ex Vasey
- Texas Desert Goldenrod - Xylothamia Palmeri (A. Gray) G.L. Nesom
- Texas Desert-thorn - Lycium Texanum Correll
- Texas Dropseed - Sporobolus Texanus Vasey
- Texas Dutchman's Pipe - Aristolochia Reticulata Jacq.
- Texas Ebony - Ebenopsis Britton & Rose
- Texas Ebony - Ebenopsis Ebano (Berl.) Barneby & Grimes
- Texas Ephemerum Moss - Ephemerum Crassinervium (Schwägr.) Hampe var. texanum (Grout) Bryan & L.E. Anderson
- Texas Evening Primrose - Oenothera Texensis P.H. Raven & Parnell
- Texas False Agave - Hechtia Texensis S. Watson
- Texas False Broomweed - Haploesthes Greggii A. Gray var. texana (J.M. Coult.) I.M. Johnst.
- Texas False Garlic - Nothoscordum Texanum M.E. Jones
- Texas Feathershank - Schoenocaulon Texanum Scheele
- Texas Fescue - Festuca Versuta Beal
- Texas Flatsedge - Cyperus Seslerioides Kunth
- Texas Flax - Linum Hudsonioides Planch.
- Texas Fluffgrass - Tridens Texanus (S. Watson) Nash
- Texas Four O'clock - Mirabilis Texensis (J.M. Coult.) B.L. Turner
- Texas Geranium - Geranium Texanum (Trel.) A. Heller
- Texas Goldentop - Euthamia Gymnospermoides Greene
- Texas Gourd - Cucurbita Pepo L. var. texana (Scheele) D. Decker
- Texas Grama - Bouteloua Rigidiseta (Steud.) Hitchc.
- Texas Greasebush - Glossopetalon Texense (Ensign) H. St. John
- Texas Greeneyes - Berlandiera Betonicifolia (Hook.) Small
- Texas Hawthorn - Crataegus Texana Buckley
- Texas Heliotrope - Heliotropium Texanum I.M. Johnst.
- Texas Hercules' Club - Zanthoxylum Hirsutum Buckley
- Texas Holdback - Pomaria Austrotexana B. Simpson
- Texas Indian Mallow - Abutilon Fruticosum Guill. & Perr.
- Texas Indian Paintbrush - Castilleja Foliolosa Hook. & Arn.
- Texas Ironweed - Vernonia Texana (A. Gray) Small
- Texas Jelly Lichen - Collema Texanum Tuck.
- Texas Kidneywood - Eysenhardtia Texana Scheele
- Texas Lady's Tresses - Spiranthes Brevilabris Lindl.
- Texas Lespedeza - Lespedeza Texana Britton
- Texas Lignum-vitae - Guaiacum Angustifolium Engelm.
- Texas Live Oak - Quercus Fusiformis Small
- Texas Lupine - Lupinus Texensis Hook.
- Texas Madeiravine - Anredera Vesicaria (Lam.) C.F. Gaertn.
- Texas Madrone - Arbutus Xalapensis Kunth
- Texas Manjack - Cordia Podocephala Torr.
- Texas Marsh Elder - Iva Texensis R.C. Jacks.
- Texas Medusulina Lichen - Medusulina Texana Müll. Arg.
- Texas Milkpea - Galactia Texana (Scheele) A. Gray
- Texas Milkvine - Matelea Producta (Torr.) Woodson
- Texas Milkweed - Asclepias Texana A. Heller
- Texas Mimosa - Mimosa Texana (A. Gray) Small
- Texas Mock Orange - Philadelphus Texensis Hu
- Texas Muhly - Muhlenbergia Texana Buckley
- Texas Mulberry - Morus Microphylla Buckley
- Texas Nightshade - Solanum Triquetrum Cav.
- Texas Nipple Cactus - Mammillaria Prolifera (Mill.) Haw.
- Texas Nipple Cactus - Mammillaria Prolifera (Mill.) Haw. var. texana (Engelm.) Borg
- Texas Palafox - Palafoxia Texana DC.
- Texas Palafox - Palafoxia Texana DC. var. ambigua (Shinners) B.L. Turner & Morris
- Texas Palafox - Palafoxia Texana DC. var. texana
- Texas Paloverde - Parkinsonia Texana (A. Gray) S. Watson
- Texas Paloverde - Parkinsonia Texana (A. Gray) S. Watson var. macra (I.M. Johnst.) Isely
- Texas Paloverde - Parkinsonia Texana (A. Gray) S. Watson var. texana
- Texas Peccania Lichen - Peccania Texana (Tuck.) Wetmore
- Texas Persimmon - Diospyros Texana Scheele
- Texas Pinkroot - Spigelia Texana (Torr. & A. Gray) A. DC.
- Texas Pipewort - Eriocaulon Texense Koern.
- Texas Plains Indian Breadroot - Pediomelum Latestipulatum (Shinners) Mahler
- Texas Plains Indian Breadroot - Pediomelum Latestipulatum (Shinners) Mahler var. appressum (D.J. Ockendon) Gandhi & L.E. B
- Texas Plains Indian Breadroot - Pediomelum Latestipulatum (Shinners) Mahler var. latestipulatum
- Texas Poppymallow - Callirhoe Scabriuscula B.L. Rob.
- Texas Prairie Parsley - Polytaenia Texana (J.M. Coult. & Rose) Mathias & Constance
- Texas Pricklyleaf - Thymophylla Setifolia Lag.
- Texas Pricklyleaf - Thymophylla Setifolia Lag. var. greggii (A. Gray) Strother
- Texas Pricklyleaf - Thymophylla Setifolia Lag. var. setifolia Lag. [excluded]
- Texas Pricklypear - Opuntia Engelmannii Salm-Dyck ex Engelm. var. lindheimeri (Engelm.) Parfitt & Pinkav
- Texas Pricklypoppy - Argemone Aurantiaca G.B. Ownbey
- Texas Quillwort - Isoetes Texana Singhurst, Rushing & W.C. Holmes
- Texas Rabbit-tobacco - Pseudognaphalium Austrotexanum G.L. Nesom
- Texas Ragwort - Senecio Ampullaceus Hook.
- Texas Red Oak - Quercus Buckleyi Nixon & Dorr
- Texas Redbud - Cercis Canadensis L. var. texensis (S. Watson) M. Hopkins
- Texas Rim Lichen - Lecanora Texana W.A. Weber
- Texas Ringstem - Anulocaulis Reflexus I.M. Johnst.
- Texas Rush - Juncus Texanus (Engelm.) Coville
- Texas Sacahuista - Nolina Texana S. Watson
- Texas Sage - Salvia Texana (Scheele) Torr.
- Texas Salt - Allolepis Söderst. & Decker
- Texas Salt - Allolepis Texana (Vasey) Söderst. & Decker
- Texas Saltbush - Atriplex Texana S. Watson
- Texas Sandmint - Rhododon Ciliatus (Benth.) Epling
- Texas Saucerflower - Antiphytum Floribundum (Torr.) A. Gray
- Texas Saxifrage - Saxifraga Texana Buckley
- Texas Screwstem - Bartonia Texana Correll
- Texas Seapurslane - Sesuvium Trianthemoides Correll
- Texas Sedge - Carex Texensis (Torr.) L.H. Bailey
- Texas Selenia - Selenia Dissecta Torr. & A. Gray
- Texas Sensitive Pea - Chamaecrista Flexuosa (L.) Greene
- Texas Sensitive Pea - Chamaecrista Flexuosa (L.) Greene var. texana (Buckley) Irwin & Barneby
- Texas Shell Lichen - Arthopyrenia Texensis (Cooke) D. Hawksw.
- Texas Shrub - Iresine Leptoclada (Hook. f.) Henrickson & Sundberg
- Texas Signalgrass - Urochloa Texana (Buckley) R. Webster
- Texas Skeletonplant - Lygodesmia Texana (Torr. & A. Gray) Greene
- Texas Skullcap - Scutellaria Texana B.L. Turner
- Texas Sleepydaisy - Xanthisma Texanum DC.
- Texas Sleepydaisy - Xanthisma Texanum DC. var. orientale Semple
- Texas Sleepydaisy - Xanthisma Texanum DC. var. texanum
- Texas Snakecotton - Froelichia Interrupta (L.) Moq.
- Texas Snakeweed - Gutierrezia Texana (DC.) Torr. & A. Gray
- Texas Snakeweed - Gutierrezia Texana (DC.) Torr. & A. Gray var. texana
- Texas Snoutbean - Rhynchosia Senna Gillies ex Hook.
- Texas Snoutbean - Rhynchosia Senna Gillies ex Hook. var. texana (Torr. & A. Gray) M.C. Johnst.
- Texas Snowbell - Styrax Platanifolius Engelm. ssp. texanus (Cory) P.W. Fritsch
- Texas Sotol - Dasylirion Texanum Scheele
- Texas Spiderwort - Tradescantia Humilis Rose
- Texas Spreadwing - Eurytaenia Texana Torr. & A. Gray
- Texas Spurge - Euphorbia Texana (Millsp. ex A. Heller) Boiss.
- Texas Star - Sabatia Campestris Nutt.
- Texas Stitchwort - Minuartia Michauxii (Fenzl) Farw. var. texana (B.L. Rob.) Mattf.
- Texas Stork's Bill - Erodium Texanum A. Gray
- Texas Sundrops - Calylophus Tubicula (A. Gray) P.H. Raven
- Texas Sunflower - Helianthus Praecox Engelm. & A. Gray
- Texas Sunflower - Helianthus Praecox Engelm. & A. Gray ssp. hirtus (Heiser) Heiser
- Texas Sunflower - Helianthus Praecox Engelm. & A. Gray ssp. praecox
- Texas Sunnybell - Schoenolirion Wrightii Sherman
- Texas Swampmallow - Pavonia Lasiopetala Scheele
- Texas Swampprivet - Forestiera Angustifolia Torr.
- Texas Tansyaster - Machaeranthera Blephariphylla (A. Gray) Shinners
- Texas Thelypody - Thelypodium Texanum (Cory) Rollins
- Texas Thistle - Cirsium Texanum Buckley
- Texas Tickseed - Coreopsis Linifolia Nutt.
- Texas Toadflax - Nuttallanthus Texanus (Scheele) D.A. Sutton
- Texas Toothleaf - Stillingia Texana I.M. Johnst.
- Texas Torchwood - Amyris Texana (Buckley) P. Wilson
- Texas Townsend Daisy - Townsendia Texensis Larsen
- Texas Trumpets - Acleisanthes Crassifolia A. Gray
- Texas Umbrellawort - Tauschia Texana A. Gray
- Texas Varilla - Varilla Texana A. Gray
- Texas Venus' Looking-glass - Triodanis Texana McVaugh
- Texas Vervain - Verbena Halei Small
- Texas Wakerobin - Trillium Texanum Buckley
- Texas Wedgescale - Sphenopholis Longiflora (Vasey) Hitchc.
- Texas Western Daisy - Astranthium Robustum (Shinners) DeJong
- Texas Wildrice - Zizania Texana Hitchc.
- Texas Wildrye - Elymus Interruptus Buckley
- Texas Wildrye - Elymus Texensis J.J.N. Campb.
- Texas Willkommia - Willkommia Texana Hitchc.
- Texas Windmill Grass - Chloris Texensis Nash
- Texas Wintergrass - Nassella Leucotricha (Trin. & Rupr.) Pohl
- Texas Woodsorrel - Oxalis Priceae Small ssp. texana (Small) Eiten
- Texas Wrightwort - Carlowrightia Texana Henrickson & Daniel
- Texas Xanthopsorella Lichen - Xanthopsorella Texana (W.A. Weber) Kalb & Hafellner
- Texas Yellowstar - Lindheimera Texana A. Gray & Engelm.
- Texas Yucca - Yucca Rupicola Scheele
- Texasfan - Meximalva Filipes (A. Gray) Fryxell
- Texasgrass - Vaseyochloa Hitchc.
- Texasgrass - Vaseyochloa Multinervosa (Vasey) Hitchc.
- Texasplume - Bauhinia Lunarioides A. Gray ex S. Watson
- Texosporium Lichen - Texosporium Nadv.
- Textile Bamboo - Bambusa Textilis McClure
- Textile Onion - Allium Textile A. Nelson & J.F. Macbr.
- Thacla Natans (Pall. ex Georgi) Deyl & Soják
- Thalassia - Thalassia Banks & Sol. ex K.D. Koenig
- Thalassia - Thalassia Hemprichii Asch.
- Thalassodendron Ciliatum (Forssk.) Hartog
- Thalassodendron Hartog
- Thalesia Fasciculata (Nutt.) Britton
- Thalesia Lutea (Parry) Rydb.
- Thalesia Uniflora (L.) Britton
- Thalia Barbata Small
- Thalia Lovegrass - Eragrostis Atrovirens (Desv.) Trin. ex Steud.
- Thalia Trichocalyx Gagnep.
- Thalictrum Alpinum L. var. hebetum B. Boivin
- Thalictrum Breitungii B. Boivin
- Thalictrum Caulophylloides Small
- Thalictrum Collinum Wallr.
- Thalictrum Confine Fernald
- Thalictrum Confine Fernald var. columbianum (Rydb.) B. Boivin
- Thalictrum Confine Fernald var. greeneanum B. Boivin
- Thalictrum Dasycarpum Fisch. & Avé-Lall. var. hypoglaucum (Rydb.) B. Boivin
- Thalictrum Fendleri Engelm. ex A. Gray var. platycarpum Trel.
- Thalictrum Hultenii B. Boivin
- Thalictrum Hypoglaucum Rydb.
- Thalictrum Minus L. ssp. kemense (Fr.) Hultén
- Thalictrum Minus L. ssp. minus
- Thalictrum Minus L. var. stipellatum (C.A. Meyer) Tamura
- Thalictrum Occidentale A. Gray var. columbianum (Rydb.) M. Peck
- Thalictrum Occidentale A. Gray var. megacarpum (Torr.) H. St. John
- Thalictrum Occidentale A. Gray var. palousense H. St. John
- Thalictrum Perelegans Greene
- Thalictrum Polycarpum (Torr.) S. Watson
- Thalictrum Polygamum Muhl. ex Spreng.
- Thalictrum Polygamum Muhl. ex Spreng. var. hebecarpum Fernald
- Thalictrum Polygamum Muhl. ex Spreng. var. intermedium B. Boivin
- Thalictrum Pubescens Pursh var. hebecarpum (Fernald) B. Boivin
- Thalictrum Pubescens Pursh var. hepaticum (Greene) Keener
- Thalictrum Revolutum DC. var. glandulosior B. Boivin
- Thalictrum Sparsiflorum Turcz. ex Fisch. & C.A. Mey. ssp. richardsonii (A. Gray) Cody
- Thalictrum Sparsiflorum Turcz. ex Fisch. & C.A. Mey. var. nevadense B. Boivin
- Thalictrum Squarrosum Stephan ex Willd.
- Thalictrum Steeleanum B. Boivin
- Thalictrum Subrotundum B. Boivin
- Thalictrum Turneri B. Boivin
- Thalictrum Venulosum Trel. var. confine (Fernald) B. Boivin
- Thalictrum Venulosum Trel. var. fissum (Greene) B. Boivin
- Thalictrum Venulosum Trel. var. lunellii (Greene) B. Boivin
- Thalictrum Venulosum Trel. var. turneri (B. Boivin) B. Boivin
- Thamnium Alleghaniense (Müll. Hal.) A. Jaeger
- Thamnium Bigelovii (Sull.) A. Jaeger
- Thamnobryum Leibergii (E. Britton) Renauld & Cardot
- Thamnobryum Moss - Thamnobryum Nieuwl.
- Thamnogala Crombiei (Mudd) D. Hawksw.
- Thamnogala D. Hawksw.
- Thamnolia Subvermicularis Asah.
- Tharp Oak - Quercus ×tharpii C.H. Mull. (pro sp.)
- Tharp's Croton - Croton Lindheimerianus Scheele var. tharpii M.C. Johnst.
- Tharp's Dropseed - Sporobolus Tharpii Hitchc.
- Tharp's Phlox - Phlox Drummondii Hook. ssp. tharpii (Whitehouse) Wherry
- Tharp's Spiderwort - Tradescantia Tharpii E.S. Anderson & Woodson
- Thaspium Aureum (L.) Nutt.
- Thaspium Aureum (L.) Nutt. var. trifoliatum (L.) J.M. Coult. & Rose
- Thaspium Barbinode (Michx.) Nutt. var. angustifolium J.M. Coult. & Rose
- Thaspium Chapmanii (J.M. Coult. & Rose) Small
- Thaspium Montanum A. Gray
- Thaspium Trifoliatum (L.) A. Gray var. flavum S.F. Blake
- Thatch Palm - Thrinax Sw.
- Thatching Grass - Hyparrhenia Andersson ex Fourn.
- Thatching Grass - Hyparrhenia Hirta (L.) Stapf
- Thaumastochloa C.e. Hubb.
- Thaumastochloa Pubescens (Domin) C.E. Hubb.
- Thaumatococcus - Thaumatococcus Benth.
- The Cedars Manzanita - Arctostaphylos Bakeri Eastw. ssp. sublaevis P.V. Wells
- Thea Bohea L.
- Thea Sinensis L.
- Thea Viridis L.
- Thecagonum Strigulosum (DC.) Terrell & H. Rob.
- Thecophyllum Sintenisii (Baker) Mez
- Thelechitonia Gracilis (Rich.) H. Rob. & Cuatrec.
- Thelechitonia Trilobata (L.) H. Rob. & Cuatrec.
- Thelenella Brasiliensis (Müll. Arg.) Vain.
- Thelenella Cinerascens (Müll. Arg.) R.C. Harris
- Thelenella Fugiens (Müll. Arg.) R.C. Harris
- Thelenella Geminipara (Malme) R.C. Harris
- Thelenella Humilis R.C. Harris
- Thelenella Lichen - Thelenella Inductula (Nyl.) H. Mayrh.
- Thelenella Lichen - Thelenella Modesta (Nyl.) Nyl.
- Thelenella Lichen - Thelenella Nyl.
- Thelenella Lichen - Thelenella Sordidula (Th. Fr.) H. Mayrh.
- Thelenella Luridella R.C. Harris
- Thelenella Pertusariella (Nyl.) Vain.
- Thelenella Rappii R.C. Harris
- Thelenella Sastreana R.C. Harris
- Thelenella Synchnogonioides (Zahlbr.) R.C. Harris
- Thelesperma Fraternum Shinners
- Thelesperma Gracile (Torr.) A. Gray
- Thelesperma Intermedium Rydb.
- Thelesperma Marginatum Rydb.
- Thelesperma Megapotamicum (Spreng.) Kuntze var. ambiguum (A. Gray) Shinners
- Thelesperma Subnudum A. Gray var. alpinum S.L. Welsh
- Thelesperma Subnudum A. Gray var. caespitosum (Dorn) S.L. Welsh
- Thelesperma Trifidum (Poir.) Britton
- Thelia Moss - Thelia Asprella Sull.
- Thelia Moss - Thelia Hirtella (Hedw.) Sull.
- Thelia Moss - Thelia Sull.
- Thelidium Acrotellum Arnold
- Thelidium Lichen - Thelidium A. Massal.
- Thelidium Lichen - Thelidium Absconditum (Hepp) Rebenh.
- Thelidium Lichen - Thelidium Aeneovinosum (Anzi) Arnold
- Thelidium Lichen - Thelidium Areolatum J.W. Thomson
- Thelidium Lichen - Thelidium Circumspersellum (Nyl.) Zschacke
- Thelidium Lichen - Thelidium Decipiens (Nyl.) Krempelh.
- Thelidium Lichen - Thelidium Incavatum Nyl. ex Mudd
- Thelidium Lichen - Thelidium Microbolum (Tuck.) Hasse
- Thelidium Lichen - Thelidium Microsporum Lynge
- Thelidium Lichen - Thelidium Minimum (A. Massal. ex Körb.) Arnold
- Thelidium Lichen - Thelidium Minutulum Körb.
- Thelidium Lichen - Thelidium Olivaceum (Schaerer) Körb.
- Thelidium Lichen - Thelidium Parvulum Arnold
- Thelidium Lichen - Thelidium Pyrenophorum (Ach.) Mudd
- Thelidium Lichen - Thelidium Velutinum (Bernh.) Körb.
- Thelidium Mesotropum (Nyl.) A.L. Sm.
- Thelidium Papulare (Fr.) Arnold
- Thelidium Transsylvanicum Zschacke
- Thelignya Lichen - Thelignya A. Massal.
- Thelignya Lichen - Thelignya Lignyota (Wahlenb.) P.M. Jørg. & Henssen
- Thelocactus Bicolor (Galeotti ex N.E. Pfeiffer) Britton & Rose ssp. flavidispinus (B
- Thelocactus Bicolor (Galeotti ex N.E. Pfeiffer) Britton & Rose var. schottii (Engelm
- Thelocactus - Thelocactus (k. Schum.) Britton & Rose
- Thelocactus Uncinatus (Galeotti) W.T. Marshall
- Thelocarpon Albomarginatum Herre
- Thelocarpon Epilithellum Nyl.
- Thelocarpon Fimicola Fink
- Thelocarpon Lichen - Thelocarpon Epibolum Nyl.
- Thelocarpon Lichen - Thelocarpon Epibolum Nyl. var. epithallinum (Leight. ex Nyl.) Salisb.
- Thelocarpon Lichen - Thelocarpon Intermediellum Nyl.
- Thelocarpon Lichen - Thelocarpon Nyl. ex Hue
- Thelocarpon Lichen - Thelocarpon Sphaerosporum H. Magn.
- Thelocarpon Lichen - Thelocarpon Superellum Nyl.
- Thelocarpon Majusculum Nyl.
- Thelocarpon Prasinellum Nyl.
- Thelomma Lichen - Thelomma A. Massal.
- Thelomma Lichen - Thelomma Mammosum (Hepp) A. Massal.
- Thelomma Lichen - Thelomma Ocellatum (Körb.) Tibell
- Thelopsis Lichen - Thelopsis Falveola Arnold
- Thelopsis Lichen - Thelopsis Inordinata Nyl.
- Thelopsis Lichen - Thelopsis Isiaca Stizenb.
- Thelopsis Lichen - Thelopsis Melathelia Nyl.
- Thelopsis Lichen - Thelopsis Nyl.
- Thelopsis Lichen - Thelopsis Rubella Nyl.
- Thelopsis Subporinella Nyl.
- Thelotrema Bahinum Ach. var. obtuascens Nyl.
- Thelotrema Carneum Eckfeldt
- Thelotrema Dilatatum (Müll. Arg.) Hale
- Thelotrema Eximium R.C. Harris
- Thelotrema Floridense R.C. Harris
- Thelotrema Halei (Tuck. & Mont.) Zahlbr.
- Thelotrema Heterosporum C. Knight ex F.M. Bailey
- Thelotrema Monospermum R.C. Harris
- Thelotrema Monosporum Nyl.
- Thelotrema Petractoides P.M. Jørg. & Brodo
- Thelotrema Polycarpoides Tuck.
- Thelotrema Porinoides Mont. & v.d. Bosch
- Thelotrema Praestans Müll. Arg.
- Thelotrema Ravenelii Tuck.
- Thelotrema Sanfordianum Zahlbr.
- Thelotrema Texanum Willey ex Nyl.
- Thelypodiopsis Argillacea S.L. Welsh & N.D. Atwood
- Thelypodiopsis Barnebyi S.L. Welsh & N.D. Atwood
- Thelypodiopsis Linearifolia (A. Gray) Al-Shehbaz
- Thelypodiopsis Sagittata (Nutt. ex Torr. & A. Gray) O.E. Schulz
- Thelypodiopsis Sagittata (Nutt. ex Torr. & A. Gray) O.E. Schulz var. ovalifolium (Rydb.)
- Thelypodium Ambiguum S. Watson
- Thelypodium Aureum Eastw.
- Thelypodium Cooperi S. Watson
- Thelypodium Deserti M.E. Jones
- Thelypodium Elegans M.E. Jones
- Thelypodium Flavescens (Hook.) S. Watson
- Thelypodium Howellii S. Watson var. spectabilis M. Peck
- Thelypodium Integrifolium (Nutt.) Endl. ex Walp. var. affine (Greene) S.L. Welsh & Reveal
- Thelypodium Integrifolium (Nutt.) Endl. ex Walp. var. complanatum (Al-Shehbaz) S.L. Welsh
- Thelypodium Integrifolium (Nutt.) Endl. ex Walp. var. gracilipes B.L. Rob.
- Thelypodium Jaegeri Rollins
- Thelypodium Laciniatum (Hook.) Endl. ex Walp. var. milleflorum (A. Nelson) Payson
- Thelypodium Laciniatum (Hook.) Endl. ex Walp. var. streptanthoides (Leiberg ex Piper) P
- Thelypodium Lasiophyllum (Hook. & Arn.) Greene
- Thelypodium Lasiophyllum (Hook. & Arn.) Greene var. inalienum B.L. Rob.
- Thelypodium Lasiophyllum (Hook. & Arn.) Greene var. rigidum (Greene) B.L. Rob.
- Thelypodium Lasiophyllum (Hook. & Arn.) Greene var. utahense (Rydb.) Jeps.
- Thelypodium Lemmonii Greene
- Thelypodium Lilacinum Greene
- Thelypodium Lilacinum Greene var. subumbellatum Payson
- Thelypodium Longifolium (Benth.) S. Watson
- Thelypodium Longifolium (Benth.) S. Watson var. catalinense M.E. Jones
- Thelypodium Micranthum (A. Gray) S. Watson
- Thelypodium Pinnatifidum (Michx.) S. Watson
- Thelypodium Purpusii Brandegee
- Thelypodium Rhomboideum Greene
- Thelypodium Rhomboideum Greene var. gracilipes (B.L. Rob.) Payson
- Thelypodium Rigidum Greene
- Thelypodium Sagittatum (Nutt. ex Torr. & A. Gray) Endl. ex Walp. var. crassicarpum Pays
- Thelypodium Sagittatum (Nutt. ex Torr. & A. Gray) Endl. ex Walp. var. ovalifolium (Rydb
- Thelypodium Sagittatum (Nutt. ex Torr. & A. Gray) Endl. ex Walp. var. vermiculare S.L.
- Thelypodium Shinnersii (M.C. Johnst.) Rollins
- Thelypodium Streptanthoides Leiberg ex Piper
- Thelypodium Suffrutescens Rollins
- Thelypodium Utahense Rydb.
- Thelypodium Vernale Wooton & Standl.
- Thelypodium Wrightii A. Gray var. tenellum M.E. Jones
- Thelypody - Thelypodium Endl.
- Thelypteris Acuminata (Houtt.) Morton [excluded]
- Thelypteris Asplenioides (Sw.) Proctor
- Thelypteris Asterothrix (Fée) Proctor [excluded]
- Thelypteris Confluens (Thunb.) Morton var. pubescens (G. Lawson) Pringle
- Thelypteris Dryopteris (L.) Slosson
- Thelypteris Gongylodes (Schkuhr) Small
- Thelypteris Gretheri (W.H. Wagner) Stone
- Thelypteris Guamensis (Holttum) Fosberg & Sachet
- Thelypteris Hawaiiensis C.F. Reed
- Thelypteris Hexagonoptera (Michx.) Weath.
- Thelypteris Hirta (Sw.) Copeland
- Thelypteris Hudsoniana (Brack.) C.F. Reed
- Thelypteris Limbosperma auct. non (All.) Fuchs
- Thelypteris Macilenta E.P. St. John
- Thelypteris Macrorhizoma E.P. St. John
- Thelypteris Megalodus (Schkuhr) Proctor
- Thelypteris Namaphila Proctor, orth. var.
- Thelypteris Namophila Proctor, database artifact
- Thelypteris Normalis (C. Chr.) Moxley
- Thelypteris Normalis (C. Chr.) Moxley var. harperi (C. Chr.) Wherry
- Thelypteris Oligocarpa (Humb. & Bonpl. ex Willd.) Ching [excluded]
- Thelypteris Oligophylla (Maxon) Proctor
- Thelypteris Palustris Schott var. haleana Fernald
- Thelypteris Patens (Sw.) Small ex R.P. St. John var. scabriuscula (C. Presl) A.R. S
- Thelypteris Patens (Sw.) Small ex R.P. St. John var. smithiana Ponce [excluded]
- Thelypteris Phegopteris (L.) Slosson
- Thelypteris Quadrangularis (Fée) Schelpe var. inconstans (C. Chr.) A.R. Sm.
- Thelypteris Quadrangularis (Fée) Schelpe var. versicolor (R.P. St. John) A.R. Sm.
- Thelypteris Reducta Small ex R.P. St. John
- Thelypteris Sancta (L.) Ching var. portoricensis (C. Chr.) Morton
- Thelypteris Saxatilis R.P. St. John
- Thelypteris Sprengelii (Kaulf.) Proctor
- Thelypteris Subpubescens (Blume) K. Iwats.
- Thelypteris Thelypterioides (Michx.) Holub
- Thelypteris Torresiana (Gaudich.) Alston
- Thelypteris Totta (Thunb.) Schelpe
- Thelypteris Truncata (Poir.) K. Iwats. [excluded]
- Thelypteris Unca R.P. St. John
- Thelypteris Unita (L.) Morton
- Thelypteris Versicolor R.P. St. John
- Thelypteris Warburgii (Kuhn & Christ) Stone
- Thelypteris ×lindheimeri (C. Chr.) Wherry
- Themeda Anathera (Nees ex Steud.) Hack.
- Themeda Australis (R. Br.) Stapf
- Themeda Frondosa (R. Br.) Merr., nom. inq.
- Themeda Gigantea auct. non (Cav.) Hack.
- Themeda Japonica (Willd.) Tanaka
- Theobroma Leiocarpum Bernoulli
- Theobroma Pentagonum Bernoulli
- Theobroma Sativa (Aubl.) Lign. & Le Bey
- Theobroma Sphaerocarpum A. Chev.
- Theobroma - Theobroma Angustifolium Moc. & Sessé ex DC.
- Theobroma - Theobroma Bicolor Humb. & Bonpl.
- Theobroma - Theobroma Grandiflorum (Willd. ex Spreng.) Schum.
- Theobroma - Theobroma L.
- Theobroma - Theobroma Mammosum Cuatrec. & Leon
- Theobroma - Theobroma Simiarum Donn. Sm.
- Thermal Bent - Agrostis Pauzhetica Prob.
- Thermopsis Arenosa A. Nelson
- Thermopsis Argentata Greene
- Thermopsis Caroliniana M.A. Curtis
- Thermopsis Gracilis Howell var. argentata (Greene) Jeps.
- Thermopsis Gracilis Howell var. venosa (Eastw.) Jeps.
- Thermopsis Hugeri (Small) Small
- Thermopsis Macrophylla Hook. & Arn. ssp. semota (Jeps.) R.M. Beauch.
- Thermopsis Macrophylla Hook. & Arn. var. agnina J.T. Howell
- Thermopsis Macrophylla Hook. & Arn. var. argentata (Greene) Jeps.
- Thermopsis Macrophylla Hook. & Arn. var. hitchcockii Isely
- Thermopsis Macrophylla Hook. & Arn. var. macrophylla
- Thermopsis Macrophylla Hook. & Arn. var. semota Jeps.
- Thermopsis Macrophylla Hook. & Arn. var. velutina (Greene) Larisey
- Thermopsis Macrophylla Hook. & Arn. var. venosa (Eastw.) Isely
- Thermopsis Mollis (Michx.) M.A. Curtis ex A. Gray var. fraxinifolia (Nutt. ex M.A.
- Thermopsis Montana Nutt. var. divaricarpa (A. Nelson) Dorn
- Thermopsis Montana Nutt. var. ovata (B.L. Rob. ex Piper) H. St. John
- Thermopsis Montana Nutt. var. venosa (Eastw.) Jeps.
- Thermopsis Ovata B.L. Rob. ex Piper
- Thermopsis Pinetorum Greene
- Thermopsis Rhombifolia (Nutt. ex Pursh) Nutt. ex Richardson var. annulocarpa (A. Nelson
- Thermopsis Rhombifolia (Nutt. ex Pursh) Nutt. ex Richardson var. arenosa (A. Nelson) La
- Thermopsis Rhombifolia (Nutt. ex Pursh) Nutt. ex Richardson var. divaricarpa (A. Nelson
- Thermopsis Rhombifolia (Nutt. ex Pursh) Nutt. ex Richardson var. montana (Nutt.) Isely
- Thermopsis Rhombifolia (Nutt. ex Pursh) Nutt. ex Richardson var. ovata (B.L. Rob. ex Pi
- Thermopsis Subglaber L.F. Hend.
- Thermutis Lichen - Thermutis Fr.
- Thermutis Lichen - Thermutis Velutina (Ach.) Flotow
- Therofon Aconitifolium (Nutt.) Millsp.
- Therofon Richardsonii (Hook.) Kuntze
- Therofon Turbinatum Rydb.
- Thesium - Thesium Arvense Horv.
- Thesium - Thesium L.
- Thespesia - Thespesia Sol. ex Corrêa
- Thevetia Neriifolia Juss. ex Steud.
- Thevetia - Thevetia Adans.
- Thevetia - Thevetia Thevetioides (Kunth) Schum.
- Thibaudia Krugii Urb. & Hoerold
- Thick Ditch Crowngrass - Paspalum Arundinaceum Poir.
- Thick-leaf Stonecrop - Sedum Dasyphyllum L.
- Thicket Anoda - Anoda Crenatiflora Ortega
- Thicket Bean - Phaseolus Polystachios (L.) Britton, Sterns & Poggenb.
- Thicket Bean - Phaseolus Polystachios (L.) Britton, Sterns & Poggenb. var. polystachios
- Thicket Bean - Phaseolus Polystachios (L.) Britton, Sterns & Poggenb. var. sinuatus (Nutt. ex Torr. &
- Thicket Clustervine - Jacquemontia Cumanensis (Kunth) Kuntze
- Thicket Creepingfern - Odontosoria Aculeata (L.) J. Sm.
- Thicket Dewberry - Rubus Permixtus Blanch.
- Thicket Globemallow - Sphaeralcea Fendleri A. Gray ssp. albescens Kearney
- Thicket Globemallow - Sphaeralcea Fendleri A. Gray ssp. elongata Kearney
- Thicket Globemallow - Sphaeralcea Fendleri A. Gray ssp. tripartita (Wooton & Standl.) Kearney
- Thicket Globemallow - Sphaeralcea Fendleri A. Gray ssp. venusta Kearney
- Thicket Groundcherry - Physalis Turbinata Medik.
- Thicket Hogwood - Clidemia Strigillosa (Sw.) DC.
- Thicket Maiden Fern - Thelypteris Leptocladia (Fée) Proctor
- Thicket Panicgrass - Panicum Trichanthum Nees
- Thicket Rattlebox - Crotalaria Virgulata Klotzsch
- Thicket Sedge - Carex Abscondita Mack.
- Thicket Tribisee - Lasiacis Ligulata Hitchc. & Chase
- Thicket Wild Coffee - Psychotria Microdon (DC.) Urb.
- Thicketwood - Jacquinia Pauciflora B. Stähl & F. Axelrod
- Thicketwort - Oplonia Microphylla (Lam.) Stearn
- Thickfoot Saltbush - Atriplex Pachypoda Stutz & G.L. Chu
- Thickhead Sedge - Carex Macloviana d'Urv.
- Thickleaf Beardtongue - Penstemon Pachyphyllus A. Gray ex Rydb.
- Thickleaf Beardtongue - Penstemon Pachyphyllus A. Gray ex Rydb. var. congestus (M.E. Jones) N.H. Holmgren
- Thickleaf Beardtongue - Penstemon Pachyphyllus A. Gray ex Rydb. var. pachyphyllus
- Thickleaf Brake - Pteris Deflexa Link
- Thickleaf Draba - Draba Crassa Rydb.
- Thickleaf Drymary - Drymaria Pachyphylla Wooton & Standl.
- Thickleaf Monardella - Monardella Hypoleuca A. Gray
- Thickleaf Monardella - Monardella Hypoleuca A. Gray ssp. hypoleuca
- Thickleaf Peperomia - Peperomia Hypoleuca Miq.
- Thickleaf Pepperweed - Lepidium Integrifolium Nutt.
- Thickleaf Pepperweed - Lepidium Integrifolium Nutt. var. heterophyllum S. Watson
- Thickleaf Pepperweed - Lepidium Integrifolium Nutt. var. integrifolium
- Thickleaf Phlox - Phlox Carolina L.
- Thickleaf Phlox - Phlox Carolina L. ssp. alta Wherry
- Thickleaf Phlox - Phlox Carolina L. ssp. angusta Wherry
- Thickleaf Phlox - Phlox Carolina L. ssp. carolina
- Thickleaf Phlox - Phlox Carolina L. ssp. turritella Wherry
- Thickleaf Ragwort - Senecio Crassulus A. Gray
- Thickleaf Scaly Polypody - Pleopeltis Squamata (L.) J. Sm.
- Thickleaf Water-willow - Justicia Crassifolia (Chapm.) Chapm. ex Small
- Thickleaf Yerba Santa - Eriodictyon Crassifolium Benth.
- Thickleaf Yerba Santa - Eriodictyon Crassifolium Benth. var. crassifolium
- Thickleaf Yerba Santa - Eriodictyon Crassifolium Benth. var. nigrescens Brand
- Thickpod Milkvetch - Astragalus Pachypus Greene
- Thickpod Milkvetch - Astragalus Pachypus Greene var. pachypus
- Thickroot Tonguefern - Elaphoglossum Glabellum J. Sm.
- Thicksepal Cryptantha - Cryptantha Crassisepala (Torr. & A. Gray) Greene
- Thicksepal Cryptantha - Cryptantha Crassisepala (Torr. & A. Gray) Greene var. crassisepala
- Thicksepal Cryptantha - Cryptantha Crassisepala (Torr. & A. Gray) Greene var. elachantha I.M. Johnst.
- Thickspike Wheatgrass - Elymus Lanceolatus (Scribn. & J.G. Sm.) Gould
- Thickspike Wheatgrass - Elymus Lanceolatus (Scribn. & J.G. Sm.) Gould ssp. lanceolatus
- Thickstem Aster - Eurybia Integrifolia (Nutt.) G.L. Nesom
- Thickstem Wild Cabbage - Caulanthus Crassicaulis (Torr.) S. Watson
- Thickstem Wild Cabbage - Caulanthus Crassicaulis (Torr.) S. Watson var. crassicaulis
- Thickstem Wild Cabbage - Caulanthus Crassicaulis (Torr.) S. Watson var. glaber M.E. Jones
- Thieret's Skullcap - Scutellaria Thieretii Shinners
- Thiers' Cup Lichen - Cladonia Thiersii S. Hammer
- Thimble Clover - Trifolium Microdon Hook. & Arn.
- Thimble Grass - Fingerhuthia Sesleriiformis Nees
- Thimbleberry - Rubus Parviflorus Nutt.
- Thimbleberry - Rubus Parviflorus Nutt. var. parviflorus
- Thimbleberry - Rubus Parviflorus Nutt. var. velutinus (Hook. & Arn.) Greene
- Thimblehead - Hymenothrix A. Gray
- Thin Beaksedge - Rhynchospora Gracillima Thwaites
- Thin Paspalum - Paspalum Setaceum Michx.
- Thin-leaf Stringybark - Eucalyptus Eugenioides Sieber ex Spreng.
- Thin-stem Lady's Mantle - Alchemilla Filicaulis Buser ssp. filicaulis
- Thin-wall Quillwort - Isoetes Microvela D.F. Brunton
- Thinfruit Labordia - Labordia Sessilis A. Gray
- Thinfruit Sedge - Carex Flaccosperma Dewey
- Thinleaf Alder - Alnus Incana (L.) Moench ssp. tenuifolia (Nutt.) Breitung
- Thinleaf Brake - Pteris Biaurita L.
- Thinleaf Bristle Fern - Trichomanes Hymenophylloides Bosch
- Thinleaf Camasey - Henriettea Membranifolia (Cogn.) Alain
- Thinleaf Cottonsedge - Eriophorum Viridicarinatum (Engelm.) Fernald
- Thinleaf Creepingfern - Bolbitis Nicotianifolia (Sw.) Alston
- Thinleaf False Brome - Brachypodium Phoenicoides (L.) Roem. & Schult.
- Thinleaf Fourwing Saltbush - Atriplex Canescens (Pursh) Nutt. var. linearis (S. Watson) Munz
- Thinleaf Goldenhead - Pyrrocoma Linearis (D.D. Keck) Kartesz & Gandhi
- Thinleaf Huckleberry - Vaccinium Membranaceum Douglas ex Torr.
- Thinleaf Late Purple Aster - Symphyotrichum Phlogifolium (Muhl. ex Willd.) G.L. Nesom
- Thinleaf Mountainmint - Pycnanthemum Montanum Michx.
- Thinleaf Pea - Lathyrus Holochlorus (Piper) C.L. Hitchc.
- Thinleaf Sedge - Carex Cephaloidea (Dewey) Dewey
- Thinleaf Sunflower - Helianthus Decapetalus L.
- Thinleaved Owl's-clover - Orthocarpus Tenuifolius (Pursh) Benth.
- Thinopyrum Intermedium (Host) Barkworth & D.R. Dewey ssp. barbulatum (Schur) Barkworth
- Thinopyrum Junceum (L.) Á. Löve p.p.
- Thinpetal Bulbophyllum - Bulbophyllum Membranaceum Teijsm. & Binn.
- Thinpetal Larkspur - Delphinium Lineapetalum Ewan
- Thinsepal Monkeyflower - Mimulus Hymenophyllus R.J. Meinke
- Thinstem Lady's Mantle - Alchemilla Filicaulis Buser
- Thinstem Lady's Mantle - Alchemilla Filicaulis Buser ssp. vestita (Buser) M.E. Bradshaw
- Thintail - Lepturus R. Br.
- Thismia - Thismia Griffith
- Thistle Cholla - Cylindropuntia Davisii (Engelm. & J.M. Bigelow) F.M. Knuth
- Thistle Cholla - Cylindropuntia Tunicata (Lehm.) F.M. Knuth
- Thistle - Cirsium Mill.
- Thistle - Cirsium ×iowense (Pammel) Fernald (pro sp.)
- Thistle Sage - Salvia Carduacea Benth.
- Thistleleaf Aster - Eurybia Eryngiifolia (Torr. & A. Gray) G.L. Nesom
- Thladiantha - Thladiantha Bunge
- Thlaspi Aileeniae Rollins
- Thlaspi Alpestre L. var. glaucum A. Nelson
- Thlaspi Alpestre auct. non L.
- Thlaspi Arcticum A.E. Porsild
- Thlaspi Australe A. Nelson
- Thlaspi Bursa-pastoris L.
- Thlaspi Californicum S. Watson
- Thlaspi Campestre L.
- Thlaspi Cochleariforme DC.
- Thlaspi Coronopifolia Bergeret
- Thlaspi Fendleri A. Gray
- Thlaspi Fendleri A. Gray var. coloradense (Rydb.) Maguire
- Thlaspi Fendleri A. Gray var. glaucum (A. Nelson) C.L. Hitchc.
- Thlaspi Fendleri A. Gray var. hesperium (Payson) C.L. Hitchc.
- Thlaspi Fendleri A. Gray var. idahoense (Payson) C.L. Hitchc.
- Thlaspi Fendleri A. Gray var. tenuipes Maguire
- Thlaspi Glaucum (A. Nelson) A. Nelson
- Thlaspi Glaucum (A. Nelson) A. Nelson var. hesperium Payson
- Thlaspi Glaucum (A. Nelson) A. Nelson var. pedunculatum Payson
- Thlaspi Hesperium (Payson) G.N. Jones
- Thlaspi Idahoense Payson
- Thlaspi Idahoense Payson var. aileeniae (Rollins) Rollins
- Thlaspi Idahoense Payson var. idahoense
- Thlaspi Montanum L.
- Thlaspi Montanum L. var. californicum (S. Watson) P.K. Holmgren
- Thlaspi Montanum L. var. fendleri (A. Gray) P.K. Holmgren
- Thlaspi Montanum L. var. idahoense (Payson) P.K. Holmgren
- Thlaspi Montanum L. var. montanum
- Thlaspi Montanum L. var. siskiyouense P.K. Holmgren
- Thlaspi Parviflorum A. Nelson
- Thlaspi Perfoliatum L.
- Thlaspi Prolixum A. Nelson
- Thlaspi Stipitatum A. Nelson
- Thollon's Strophanthus - Strophanthus Thollonii Franchet
- Thomas' Bird's-eye Bush - Ochna Thomasiana Engl. & Gilg
- Thomas' Buckwheat - Eriogonum Thomasii Torr.
- Thomas' Lidflower - Calyptranthes Thomasiana Berg
- Thomas' Sage - Salvia Thomasiana Urb.
- Thompkins' Sedge - Carex Tompkinsii J.T. Howell
- Thompson's Beardtongue - Penstemon Thompsoniae (A. Gray) Rydb.
- Thompson's Beardtongue - Penstemon Thompsoniae (A. Gray) Rydb. ssp. thompsoniae
- Thompson's Buckwheat - Eriogonum Thompsoniae S. Watson
- Thompson's Buckwheat - Eriogonum Thompsoniae S. Watson var. albiflorum Reveal
- Thompson's Buckwheat - Eriogonum Thompsoniae S. Watson var. thompsoniae
- Thompson's Clover - Trifolium Thompsonii Morton
- Thompson's Cryptantha - Cryptantha Thompsonii I.M. Johnst.
- Thompson's Dalea - Psorothamnus Thompsoniae (Vail) S.L. Welsh & N.D. Atwood
- Thompson's Dalea - Psorothamnus Thompsoniae (Vail) S.L. Welsh & N.D. Atwood var. thompsoniae
- Thompson's Desertparsley - Lomatium Thompsonii (Mathias) Cronquist
- Thompson's Draba - Draba Lonchocarpa Rydb. var. thompsonii (C.L. Hitchc.) Rollins
- Thompson's Gymnosporia - Gymnosporia Thompsonii Merr.
- Thompson's Indian Paintbrush - Castilleja Thompsonii Pennell
- Thompson's Iris - Iris Thompsonii R.C. Foster
- Thompson's Mistmaiden - Romanzoffia Thompsonii Marttala
- Thompson's Peteria - Peteria Thompsoniae S. Watson
- Thompson's Pincushion - Chaenactis Thompsonii Cronquist
- Thompson's Rockcress - Arabis Microphylla Nutt. var. thompsonii Rollins
- Thompson's Sandwort - Arenaria Franklinii Douglas ex Hook. var. thompsonii M. Peck
- Thompson's Waterleaf - Hydrophyllum Capitatum Douglas ex Benth. var. thompsonii (M. Peck) Constance
- Thompson's Yucca - Yucca Thompsoniana Trel.
- Thomson's Calcareous Moss - Mnium Thomsonii Schimp.
- Thomson's Cup Lichen - Cladonia Thomsonii Ahti
- Thomson's Porpidia Lichen - Porpidia Thomsonii Gowan
- Thomson's Rim Lichen - Lecanora Thomsonii H. Magn.
- Thoracostachyum Sumatranum (Miq.) Kurz
- Thorn Skeletonweed - Pleiacanthus Spinosus (Nutt.) Rydb.
- Thorn Wattle - Acacia Continua Benth.
- Thorn-mint - Acanthomintha (a. Gray) A. Gray
- Thornber's Buckhorn Cholla - Cylindropuntia Acanthocarpa (Engelm. & J.M. Bigelow) F.M. Knuth var. thornberi (Thornb. & Bo
- Thornber's Nipple Cactus - Mammillaria Thornberi Orcutt
- Thorne's Beaksedge - Rhynchospora Thornei Kral
- Thorne's Buckwheat - Eriogonum Thornei (Reveal & Henrickson) L.M. Shultz
- Thorne's Sedge - Carex Thornei Naczi
- Thornless Dewberry - Rubus Uniformis L.H. Bailey
- Thorny Dewberry - Rubus Aculiferus L.H. Bailey
- Thorny Olive - Elaeagnus Pungens Thunb.
- Thorny Popolo - Solanum Incompletum Dunal
- Thoroughwort - Chromolaena Dc.
- Thoroughwort - Conoclinium Dc.
- Thoroughwort - Critonia P. Br.
- Thoroughwort - Eupatorium L.
- Thoroughwort - Eupatorium ×pinnatifidum Elliott
- Thoroughwort - Eupatorium ×truncatum Muhl. ex Willd. (pro sp.)
- Thoroughwort - Fleischmannia Sch. Bip.
- Thoroughwort - Hebeclinium Dc.
- Thoroughwort - Koanophyllon Arruda
- Thouinia Portoricensis Radlk.
- Thouinia - Thouinia Poit.
- Thread Lichen - Ephebe Fr.
- Thread Lichen - Ephebe Lanata (L.) Vain.
- Thread Lichen - Ephebe Ocellata Henssen
- Thread Lichen - Ephebe Perspinulosa Nyl.
- Thread Lichen - Ephebe Solida Bornet
- Thread Linanthus - Leptosiphon Filipes (Benth.) J.M. Porter & L.A. Johnson
- Thread Rush - Juncus Filiformis L.
- Threadbranch Stitchwort - Minuartia Filiorum (Maguire) McNeill
- Threadleaf Arrowhead - Sagittaria Filiformis J.G. Sm.
- Threadleaf Beaksedge - Rhynchospora Filifolia A. Gray
- Threadleaf Beardtongue - Penstemon Filiformis (D.D. Keck) D.D. Keck
- Threadleaf Bladderpod - Lesquerella Angustifolia (Nutt. ex Torr. & A. Gray) S. Watson
- Threadleaf Brodiaea - Brodiaea Filifolia S. Watson
- Threadleaf Crowfoot - Ranunculus Trichophyllus Chaix
- Threadleaf Crowfoot - Ranunculus Trichophyllus Chaix var. eradicatus (Laest.) W. Drew
- Threadleaf Crowfoot - Ranunculus Trichophyllus Chaix var. trichophyllus
- Threadleaf Evening Primrose - Oenothera Linifolia Nutt.
- Threadleaf False Foxglove - Agalinis Setacea (J.F. Gmel.) Raf.
- Threadleaf Fleabane - Erigeron Filifolius (Hook.) Nutt.
- Threadleaf Fleabane - Erigeron Filifolius (Hook.) Nutt. var. filifolius
- Threadleaf Fleabane - Erigeron Filifolius (Hook.) Nutt. var. robustior M. Peck
- Threadleaf Giant Hyssop - Agastache Rupestris (Greene) Standl.
- Threadleaf Glowwort - Sartwellia Flaveriae A. Gray
- Threadleaf Horsebrush - Tetradymia Filifolia Greene
- Threadleaf Phacelia - Phacelia Linearis (Pursh) Holz.
- Threadleaf Phlox - Phlox Mesoleuca Greene
- Threadleaf Ragwort - Senecio Flaccidus Less.
- Threadleaf Ragwort - Senecio Flaccidus Less. var. flaccidus
- Threadleaf Sedge - Carex Filifolia Nutt.
- Threadleaf Snakeweed - Gutierrezia Microcephala (DC.) A. Gray
- Threadleaf Sundew - Drosera Filiformis Raf.
- Threadplant - Nemacladus Nutt.
- Threadstalk Milkvetch - Astragalus Speirocarpus A. Gray
- Threadstalk Speedwell - Veronica Filiformis Sm.
- Threadstem Carpetweed - Mollugo Cerviana (L.) Ser.
- Threadstem Pincushionplant - Navarretia Filicaulis (Torr. ex A. Gray) Greene
- Threadstem Sandmat - Chamaesyce Revoluta (Engelm.) Small
- Three Peaks Jewelflower - Streptanthus Morrisonii F.W. Hoffm. ssp. elatus F.W. Hoffm.
- Three Toothed Saxifrage - Saxifraga Tricuspidata Rottb.
- Three-angle Spikerush - Eleocharis Tricostata Torr.
- Three-awn Grass - Stipagrostis Pungens (Desf.) De Winter
- Three-awned Goatgrass - Aegilops Neglecta Req. ex Bertol.
- Three-flower Labordia - Labordia Triflora Hillebr.
- Three-hulled Rush - Juncus Triglumis L.
- Three-lobe Violet - Viola Triloba Schwein.
- Three-lobe Violet - Viola Triloba Schwein. var. dilatata (Elliott) Brainerd
- Three-lobe Violet - Viola Triloba Schwein. var. triloba
- Three-lobed Rockdaisy - Perityle Gracilis (M.E. Jones) Rydb.
- Three-rib Arrowgrass - Triglochin Striata Ruiz & Pav.
- Three-way Sedge - Dulichium Arundinaceum (L.) Britton
- Three-way Sedge - Dulichium Arundinaceum (L.) Britton var. arundinaceum
- Three-way Sedge - Dulichium Arundinaceum (L.) Britton var. boreale Lepage
- Threeawn - Aristida L.
- Threebirds - Triphora Trianthophora (Sw.) Rydb.
- Threeblossom Lidflower - Calyptranthes Triflora Alain
- Threebract Loosestrife - Lythrum Tribracteatum Salzm. ex Spreng.
- Threebract Onion - Allium Tribracteatum Torr.
- Threecorner Leek - Allium Triquetrum L.
- Threecornerjack - Emex Campd.
- Threeflower Hawthorn - Crataegus Triflora Chapm.
- Threeflower Melicgrass - Melica Nitens (Scribn.) Nutt. ex Piper
- Threeflower Rush - Juncus Drummondii E. Mey. var. subtriflorus (E. Mey.) C.L. Hitchc.
- Threeflower Snakeweed - Thurovia Triflora Rose
- Threeflower Ticktrefoil - Desmodium Triflorum (L.) DC.
- Threefold - Trixis P. Br.
- Threefork Polypody - Enterosora Baker
- Threefork Polypody - Enterosora Trifurcata (L.) Bishop
- Threehearts - Tricardia Watsonii Torr. ex S. Watson
- Threeleaf Arrowhead - Sagittaria Trifolia L.
- Threeleaf Blackberry - Rubus Triphyllus Thunb.
- Threeleaf Cayratia - Cayratia Trifolia (L.) Domin
- Threeleaf Derris - Derris Trifoliata Lour.
- Threeleaf False Lily Of The Valley - Maianthemum Trifolium (L.) Sloboda
- Threeleaf Foamflower - Tiarella Trifoliata L.
- Threeleaf Foamflower - Tiarella Trifoliata L. var. laciniata (Hook.) Wheelock
- Threeleaf Foamflower - Tiarella Trifoliata L. var. trifoliata
- Threeleaf Goldback Fern - Pityrogramma Trifoliata (L.) R. Tryon
- Threeleaf Goldthread - Coptis Trifolia (L.) Salisb.
- Threeleaf Halberd Fern - Tectaria Trifoliata (L.) Cav.
- Threeleaf Indigo - Indigofera Trifoliata L.
- Threeleaf Lewisia - Lewisia Triphylla (S. Watson) B.L. Rob.
- Threeleaf Maiden Fern - Thelypteris Triphylla (Sw.) K. Iwats.
- Threeleaf Shrubverbena - Lantana Trifolia L.
- Threeleaf Soapberry - Sapindus Trifoliatus L.
- Threeleaf Woodsorrel - Oxalis Trilliifolia Hook.
- Threeleaflet Dewberry - Rubus Trifrons Blanch.
- Threelobe Beggarticks - Bidens Tripartita L.
- Threelobe Buttercup - Ranunculus Trilobus Desf.
- Threelobe False Mallow - Malvastrum Coromandelianum (L.) Garcke
- Threelobe Oxytheca - Oxytheca Trilobata A. Gray
- Threelobe Pygmymelon - Psiguria Trilobata (L.) Howard
- Threelobe Rosemallow - Hibiscus Trilobus Aubl.
- Threelobed Typhonium - Typhonium Trilobatum (L.) Schott
- Threelocule Corchorus - Corchorus Trilocularis L.
- Threenerve Fleabane - Erigeron Subtrinervis Rydb. ex Porter & Britton
- Threenerve Fleabane - Erigeron Subtrinervis Rydb. ex Porter & Britton var. conspicuus (Rydb.) Cronquist
- Threenerve Fleabane - Erigeron Subtrinervis Rydb. ex Porter & Britton var. subtrinervis
- Threenerve Goldenrod - Solidago Velutina DC.
- Threenerve Roughleaf - Sagraea Scalpta (Vent.) Naud.
- Threepart Violet - Viola Tripartita Elliott
- Threeparted Miterwort - Mitella Trifida Graham
- Threeparted Miterwort - Mitella Trifida Graham var. trifida
- Threeparted Miterwort - Mitella Trifida Graham var. violacea (Rydb.) Rosend.
- Threepetal Bedstraw - Galium Trifidum L.
- Threepetal Bedstraw - Galium Trifidum L. ssp. columbianum (Rydb.) Hultén
- Threepetal Bedstraw - Galium Trifidum L. ssp. halophilum (Fernald & Wiegand) Puff
- Threepetal Bedstraw - Galium Trifidum L. ssp. subbiflorum (Wiegand) Piper
- Threepetal Bedstraw - Galium Trifidum L. ssp. trifidum
- Threeray Tarweed - Hemizonia Lobbii Greene
- Threesection Buttercup - Ranunculus Eschscholtzii Schltdl. var. trisectus (Eastw.) L.D. Benson
- Threeseed Croton - Croton Lindheimerianus Scheele
- Threeseed Croton - Croton Lindheimerianus Scheele var. lindheimerianus
- Threeseed Phlox - Phlox Triovulata Thurb. ex Torr.
- Threeseeded Sedge - Carex Trisperma Dewey
- Threeseeded Sedge - Carex Trisperma Dewey var. trisperma
- Threespike Fiddlewood - Citharexylum Tristachyum Turcz.
- Threespike Goosegrass - Eleusine Tristachya (Lam.) Lam.
- Threestamen Waterwort - Elatine Triandra Schkuhr
- Threetip Sagebrush - Artemisia Tripartita Rydb.
- Threetip Sagebrush - Artemisia Tripartita Rydb. ssp. tripartita
- Threetooth Blazingstar - Mentzelia Tridentata (Davidson) H.J. Thomp. & Roberts
- Threetooth Hawkweed - Hieracium Tridentatum Fr.
- Threetooth Horkelia - Horkelia Tridentata Torr.
- Threetooth Horkelia - Horkelia Tridentata Torr. ssp. flavescens (Rydb.) D.D. Keck
- Threetooth Horkelia - Horkelia Tridentata Torr. ssp. tridentata
- Threetooth Ragwort - Packera Tridenticulata (Rydb.) W.A. Weber & Á. Löve
- Thrift Mock Goldenweed - Stenotus Armerioides Nutt.
- Thrift Mock Goldenweed - Stenotus Armerioides Nutt. var. armerioides
- Thrift Seapink - Armeria Maritima (Mill.) Willd.
- Thrift Seapink - Armeria Maritima (Mill.) Willd. ssp. maritima
- Thrinax Floridana Sarg.
- Thrinax Keyensis Sarg.
- Thrinax Microcarpa Sarg.
- Thrinax Morrisii H. Wendl.
- Thrinax Multiflora sensu R.W. Read, non Mart.
- Thrinax Parviflora auct. non Sw.
- Thrinax Ponceana O.F. Cook
- Thrinax Praeceps O.F. Cook
- Thrincoma Alta O.F. Cook
- Thrombium Lichen - Thrombium Discordans (Nyl.) Zahlbr.
- Thrombium Lichen - Thrombium Epigaeum (Pers.) Wallr.
- Thrombium Lichen - Thrombium Wallr.
- Thryallis Angustifolia (Benth.) Kuntze
- Thryallis Glauca (Cav.) Kuntze
- Thryallis Gracilis (Bartlett) Kuntze
- Thuidium Abietinum (Hedw.) Schimp.
- Thuidium Bolanderi (Best) Par.
- Thuidium Crispifolium (Hook.) Lindb.
- Thuidium Delicatulum (Hedw.) Schimp. var. radicans (Kindb.) H.A. Crum, Steere & L.E.
- Thuidium Delicatulum (Hedw.) Schimp. var. repens Kindb.
- Thuidium Involvens (Hedw.) Mitt.
- Thuidium Lanatum (Brid.) Hag
- Thuidium Leuconeuron (Sull. & Lesq.) Lesq.
- Thuidium Lignicola Kindb.
- Thuidium Microphyllum (Hedw.) A. Jaeger
- Thuidium Microphyllum (Hedw.) A. Jaeger var. lignicola (Kindb.) Best
- Thuidium Microphyllum (Hedw.) A. Jaeger var. obtusum Grout
- Thuidium Minutulum (Hedw.) Schimp.
- Thuidium Moss - Thuidium Recognitum (Hedw.) Lindb.
- Thuidium Moss - Thuidium Schimp.
- Thuidium Paludosum (Sull.) Rau & Herv.
- Thuidium Pseudo-gracile Kindb.
- Thuidium Pygmaeum Schimp.
- Thuidium Schistocalyx (Müll. Hal.) Mitt.
- Thuidium Scitum (P. Beauv.) Austin
- Thuidium Scitum (P. Beauv.) Austin var. aestivale Austin
- Thuidium Virginianum (Brid.) Schimp.
- Thuja Occidentalis L. f. malonyana C.K. Schneid.
- Thuja Occidentalis L. var. fastigiata H. Jaeger
- Thuja Occidentalis L. var. nigra L.H. Bailey
- Thuja Occidentalis L. var. pyramidalis Zederb.
- Thuja Orientalis L.
- Thuja Orientalis L. var. aurea (Carrière) Rehder
- Thule Arctopeltis Lichen - Arctopeltis Thuleana Poelt
- Thunberg's Amaranthus - Amaranthus Thunbergii Moq.
- Thunberg's Gardenia - Gardenia Thunbergia L. f.
- Thunberg's Geranium - Geranium Thunbergii Siebold ex Lindl. & Paxton
- Thunberg's Lespedeza - Lespedeza Thunbergii (DC.) Nakai
- Thunberg's Meadowsweet - Spiraea Thunbergii Siebold ex Blume
- Thunbergia - Thunbergia Retz.
- Thunbergia Volubilis Pers.
- Thurber's Bog Orchid - Platanthera Limosa Lindl.
- Thurber's Buckwheat - Eriogonum Thurberi Torr.
- Thurber's Checkerbloom - Sidalcea Neomexicana A. Gray ssp. thurberi (B.L. Rob.) C.L. Hitchc.
- Thurber's Cotton - Gossypium Thurberi Todaro
- Thurber's Desert Honeysuckle - Anisacanthus Thurberi (Torr.) A. Gray
- Thurber's Desertpeony - Acourtia Thurberi (A. Gray) Reveal & R.M. King
- Thurber's Diphysa - Diphysa Thurberi (A. Gray) Rydb.
- Thurber's Fescue - Festuca Thurberi Vasey
- Thurber's Giant-trumpets - Macromeria Viridiflora DC. var. thurberi (A. Gray) I.M. Johnst.
- Thurber's Hoarypea - Tephrosia Thurberi (Rydb.) C.E. Wood
- Thurber's Indian Mallow - Abutilon Thurberi A. Gray
- Thurber's Milkvetch - Astragalus Thurberi A. Gray
- Thurber's Morning-glory - Ipomoea Thurberi A. Gray
- Thurber's Muhly - Muhlenbergia Thurberi Rydb.
- Thurber's Needlegrass - Achnatherum Thurberianum (Piper) Barkworth
- Thurber's Penstemon - Penstemon Thurberi Torr.
- Thurber's Pepperweed - Lepidium Thurberi Wooton
- Thurber's Sandpaper Plant - Petalonyx Thurberi A. Gray
- Thurber's Sandpaper Plant - Petalonyx Thurberi A. Gray ssp. thurberi
- Thurber's Sedge - Carex Thurberi Dewey
- Thurber's Sneezeweed - Helenium Thurberi A. Gray
- Thurber's Stemsucker - Pilostyles Thurberi A. Gray
- Thurber's Wirelettuce - Stephanomeria Thurberi A. Gray
- Thurberia Thespesioides A. Gray
- Thurovia - Thurovia Rose
- Thurow's Panicgrass - Dichanthelium Acuminatum (Sw.) Gould & C.A. Clark var. thurowii (Scribn. & J.G. Sm.) Goul
- Thurston Grass - Urochloa Glumaris (Trin.) Veldkamp
- Thyana Portoricensis (Radlk.) Britton
- Thyana Striata (Radlk.) Britton
- Thyella Tamnifolia (L.) Raf.
- Thyme - Thymus L.
- Thymelaea - Thymelaea Mill.
- Thymeleaf Bluet - Houstonia Serpyllifolia Michx.
- Thymeleaf Buckwheat - Eriogonum Thymoides Benth.
- Thymeleaf Dragonhead - Dracocephalum Thymiflorum L.
- Thymeleaf Loosestrife - Lythrum Thymifolia L.
- Thymeleaf Melaleuca - Melaleuca Thymifolia Sm.
- Thymeleaf Mesamint - Pogogyne Serpylloides (Torr.) A. Gray
- Thymeleaf Mock Orange - Philadelphus Serpyllifolius A. Gray
- Thymeleaf Pinweed - Lechea Minor L.
- Thymeleaf Sandmat - Chamaesyce Serpyllifolia (Pers.) Small
- Thymeleaf Sandmat - Chamaesyce Serpyllifolia (Pers.) Small ssp. hirtella (Engelm. ex S. Watson) Koutnik
- Thymeleaf Sandmat - Chamaesyce Serpyllifolia (Pers.) Small ssp. serpyllifolia
- Thymeleaf Sandwort - Arenaria Serpyllifolia L.
- Thymeleaf Saxifrage - Saxifraga Serpyllifolia Pursh
- Thymeleaf Speedwell - Veronica Serpyllifolia L.
- Thymeleaf Speedwell - Veronica Serpyllifolia L. ssp. serpyllifolia
- Thymophylla Polychaeta A. Gray
- Thymophylla Setifolia Lag. var. radiata (A. Gray) Strother, nom. illeg.
- Thymus Arcticus (Durand) Ronniger
- Thymus Drucei Ronniger
- Thymus Lanicaulis Ronniger
- Thymus Marschallianus Willd.
- Thymus Pannonicus All.
- Thymus Serpyllum L. ssp. chamaedrys (Fr.) Voll.
- Thymus Serpyllum L. var. albus hort.
- Thymus Serpyllum auct. non L.
- Thymus Thracicus Velen.
- Thymus - Thymus Capitatus (L.) Hoffsgg. & Link
- Thyrea Confusa Henssen
- Thyrea Demangeonii (Moug. & Mont.) Fink
- Thyrea Lichen - Thyrea A. Massal.
- Thyrea Nigritella Lettau
- Thyrea Pulvinata auct.
- Thyrea Pyrenoides (Nyl.) Fink
- Thyridolepis Mitchelliana (Nees) S.T. Blake
- Thyridolepis S.t. Blake
- Thyrsacanthus Cuspidatus Nees
- Thyrsacanthus Strictus Nees
- Thyrsanthella Difformis (Walter) Pichon
- Thysanella Fimbriata (Elliott) A. Gray
- Thysanella Robusta Small
- Thysanocarpus Amplectens Greene
- Thysanocarpus Curvipes Hook. var. elegans (Fisch. & C.A. Mey.) B.L. Rob.
- Thysanocarpus Curvipes Hook. var. eradiatus Jeps.
- Thysanocarpus Curvipes Hook. var. longistylus Jeps.
- Thysanocarpus Elegans Fisch. & C.A. Mey.
- Thysanocarpus Laciniatus Nutt. ssp. desertorum (A. Heller) Abrams
- Thysanocarpus Laciniatus Nutt. var. conchuliferus (Greene) Jeps.
- Thysanocarpus Laciniatus Nutt. var. crenatus (Nutt.) W.H. Brewer
- Thysanocarpus Laciniatus Nutt. var. emarginatus (Greene) Jeps.
- Thysanocarpus Laciniatus Nutt. var. hitchcockii Munz
- Thysanocarpus Laciniatus Nutt. var. ramosus (Greene) Munz
- Thysanocarpus Laciniatus Nutt. var. rigidus Munz
- Thysanocarpus Pusillus Hook.
- Thysanolaena Maxima (Roxb.) Kuntze [excluded]
- Ti Ngahere - Cordyline Banksii Hook. f.
- Tiarella Californica (Kellogg) Rydb.
- Tiarella Laciniata Hook.
- Tiarella Macrophylla Small p.p.
- Tiarella Menziesii Pursh
- Tiarella Trifoliata L. ssp. unifoliata (Hook.) Kern
- Tiarella Unifoliata Hook.
- Tiarella Wherryi Lakela
- Tiaridium Indicum (L.) Lehm.
- Tibet Milkvetch - Astragalus Tibetanus Benth. ex Bunge
- Tibetan Hazelnut - Corylus Ferox Wall. var. thibetica (Batalin) Franchet
- Tibey De Cresta - Columnea Ambigua (Urb.) Morley
- Tibey Parasito - Columnea Scandens L.
- Tibey Parasito - Columnea Scandens L. var. tulae (Urb.) Wiehler
- Tibey Trepador - Hillia Parasitica Jacq.
- Tibey Tupa - Lobelia Portoricensis (Vatke) Urb.
- Tibey-amarillo - Rhytidophyllum Auriculatum Hook.
- Tibey-amarillo - Rhytidophyllum Mart.
- Tibig - Ficus Nota (Blanco) Merr.
- Tibouchina Laxa (Desr.) Cogn.
- Tiburon Buckwheat - Eriogonum Luteolum Greene var. caninum (Greene) Reveal
- Tiburon Indian Paintbrush - Castilleja Affinis Hook. & Arn. ssp. neglecta (Zeile) T.I. Chuang & Heckard
- Tiburon Jewelflower - Streptanthus Niger Greene
- Tiburon Mariposa Lily - Calochortus Tiburonensis A.J. Hill
- Tichothecium Pygmaeum Körb.
- Tichothecium Zahlbrucknerella Henssen
- Tick Quackgrass - Thinopyrum Pycnanthum (Godr.) Barkworth
- Tick Trefoil - Codariocalyx Hassk.
- Tickbush - Kunzea Ambigua (Sm.) Druce
- Tickletongue - Zanthoxylum Parvum Shinners
- Tickseed - Coreopsis L.
- Ticktrefoil - Desmodium Desv.
- Ticktrefoil - Desmodium Sericophyllum Schltdl.
- Ticktrefoil - Desmodium Umbellatum (L.) DC.
- Tidal Spikerush - Eleocharis Aestuum D.M. Hines ex A. Haines
- Tidalmarsh Amaranth - Amaranthus Cannabinus (L.) Sauer
- Tidalmarsh Flatsedge - Cyperus Serotinus Rottb.
- Tidestrom's Beardtongue - Penstemon Tidestromii Pennell
- Tidestrom's Lupine - Lupinus Tidestromii Greene
- Tidestrom's Lupine - Lupinus Tidestromii Greene var. layneae (Eastw.) Munz
- Tidestrom's Lupine - Lupinus Tidestromii Greene var. tidestromii
- Tidestrom's Milkvetch - Astragalus Tidestromii (Rydb.) Clokey
- Tidestromia Lanuginosa (Nutt.) Standl. var. carnosa (Steyerm.) Cory
- Tidestromia Oblongifolia (S. Watson) Standl. ssp. cryptantha (S. Watson) Wiggins [exclude
- Tidytips - Layia Hook. & Arn. ex DC.
- Tiedemannia Canbyi (J.M. Coult. & Rose) Feist & S.R. Downie
- Tiedemannia Filiformis (Walter) Feist & S.R. Downie
- Tiehm's Beardtongue - Penstemon Tiehmii N.H. Holmgren
- Tiehm's Blazing Star - Mentzelia Tiehmii N.H. Holmgren & P.K. Holmgren
- Tiehm's Buckwheat - Eriogonum Tiehmii Reveal
- Tiehm's Milkvetch - Astragalus Tiehmii Barneby
- Tietongue - Coccoloba Diversifolia Jacq.
- Tievine - Ipomoea Cordatotriloba Dennst.
- Tievine - Ipomoea Cordatotriloba Dennst. var. cordatotriloba
- Tifton Burclover - Medicago Rigidula (L.) All.
- Tiger Beardtongue - Penstemon Mensarum Pennell
- Tiger Grass - Thysanolaena Latifolia (Roxb. ex Hornem.) Honda
- Tiger Grass - Thysanolaena Nees
- Tiger Lily - Lilium Lancifolium Thunb.
- Tiger Orchid - Elleanthus C. Presl
- Tiger Orchid - Maxillaria Ruiz & Pav.
- Tiger's Claw - Erythrina Variegata L.
- Tiger's Claw - Erythrina Variegata L. var. orientalis L.
- Tiger-pear - Opuntia Aurantiaca Lindl.
- Tigertongue - Opuntia Ellisiana Griffiths
- Tight-flower Swampmallow - Pavonia Corymbosa (Sw.) Willd.
- Tigna Potato - Solanum Leptosepalum Correll
- Tigridia Pavonia (L. f.) DC. [excluded]
- Tigridia Purpurea (Herb.) Shinners
- Tilesius' Wormwood - Artemisia Tilesii Ledeb.
- Tilesius' Wormwood - Artemisia Tilesii Ledeb. ssp. elatior (Torr. & A. Gray) Hultén
- Tilesius' Wormwood - Artemisia Tilesii Ledeb. ssp. gormanii (Rydb.) Hultén
- Tilesius' Wormwood - Artemisia Tilesii Ledeb. ssp. tilesii
- Tilesius' Wormwood - Artemisia Tilesii Ledeb. ssp. unalaschcensis (Besser) Hultén
- Tilia Americana L. var. neglecta (Spach) Fosberg
- Tilia Argentea DC.
- Tilia Australis Small
- Tilia Caroliniana Mill.
- Tilia Caroliniana Mill. var. rhoophila Sarg.
- Tilia Eburnea Ashe
- Tilia Europaea L., database artifact
- Tilia Floridana Small
- Tilia Floridana Small var. hypoleuca Sarg.
- Tilia Floridana Small var. oblongifolia Sarg.
- Tilia Georgiana Sarg.
- Tilia Glabra Vent.
- Tilia Heterophylla Vent.
- Tilia Heterophylla Vent. var. michauxii (Nutt.) Sarg.
- Tilia Lasioclada Sarg.
- Tilia Leptophylla (Vent.) Small
- Tilia Leucocarpa Ashe
- Tilia Leucocarpa Ashe var. brevipedunculata (Sarg.) Ashe
- Tilia Littoralis Sarg.
- Tilia Michauxii Nutt.
- Tilia Monticola Sarg.
- Tilia Neglecta Spach
- Tilia Palmeri F.C. Gates
- Tilia Porracea Ashe
- Tilia Pubescens Aiton
- Tilia Tomentosa Moench ssp. petiolaris (DC.) Soó
- Tilia Truncata Spach
- Tilia Venulosa Sarg.
- Tilia ×flavescens A. Braun ex Döll
- Tilia ×moltkei Spath ex C.K. Schneid.
- Tilia ×vulgaris Hayne (pro sp.)
- Tiling's Monkeyflower - Mimulus Tilingii Regel
- Tiling's Monkeyflower - Mimulus Tilingii Regel var. tilingii
- Tilingia - Tilingia Regel & Tiling
- Tillaea Angustifolia Nutt.
- Tillaea Angustifolia Nutt. var. bolanderi S. Watson
- Tillaea Aquatica L.
- Tillaea Aquatica L. var. drummondii (Torr. & A. Gray) Jeps.
- Tillaea Aquatica L. var. drummondii sensu (Torr. & A. Gray) Jeps. p.p.
- Tillaea Ascendens Eaton
- Tillaea Bolanderi (S. Watson) Greene
- Tillaea Drummondii Torr. & A. Gray
- Tillaea Drummondii Torr. & A. Gray var. bolanderi (S. Watson) Jeps.
- Tillaea Erecta Hook. & Arn.
- Tillaea Erecta Hook. & Arn. ssp. eremica (Jeps.) Wiggins
- Tillaea Erecta Hook. & Arn. var. eremica Jeps.
- Tillaea Leptopetala Benth.
- Tillaea Longipes Rose
- Tillaea Minima Gay
- Tillaea Minima Miers ex Hook. & Arn. var. subsimplex S. Watson
- Tillaea Minima Miers ex Hook. & Arn., non Gay, nom. illeg.
- Tillaea Muscosa L.
- Tillaea Rubescens Kunth
- Tillaea Solierii C. Gay
- Tillaea Vaillantii sensu A. Gray, non Willd.
- Tillaea Viridis S. Watson
- Tillaeastrum Aquaticum (L.) Britton
- Tillaeastrum Drummondii (Torr. & A. Gray) Britton
- Tillaeastrum Drummondii sensu (Torr. & A. Gray) Britton p.p.
- Tillaeastrum Pringlei Rose
- Tillaeastrum Vaillantii auct. non (Willd.) Britton
- Tillaeastrum Viride (S. Watson) Britton
- Tillandsia Aloifolia Hook.
- Tillandsia Circinnata auct. non Schltdl.
- Tillandsia Fasciculata Sw. var. floridana L.B. Sm.
- Tillandsia Festucoides auct. non Brongn. ex Mez
- Tillandsia Hystricina Small
- Tillandsia Juncea auct. non (Ruiz & Pav.) Poir.
- Tillandsia Lindenii Regel [excluded]
- Tillandsia Myriophylla Small
- Tillandsia Nutans Sw.
- Tillandsia Polystachya auct. non (L.) L.
- Tillandsia Pulchella Hook.
- Tillandsia Sublaxa Baker
- Tillandsia Tenuifolia Mez, non L.
- Tillandsia Valenzuelana A. Rich.
- Tillandsia ×smalliana H. Luther, nom. inval.
- Tilol - Garcinia Matudae Kaneh.
- Timber Milkvetch - Astragalus Miser Douglas ex Hook.
- Timber Milkvetch - Astragalus Miser Douglas ex Hook. var. crispatus (M.E. Jones) Cronquist
- Timber Milkvetch - Astragalus Miser Douglas ex Hook. var. miser
- Timber Milkvetch - Astragalus Miser Douglas ex Hook. var. oblongifolius (Rydb.) Cronquist
- Timber Milkvetch - Astragalus Miser Douglas ex Hook. var. serotinus (A. Gray ex Cooper) Barneby
- Timber Milkvetch - Astragalus Miser Douglas ex Hook. var. tenuifolius (Nutt.) Barneby
- Timber Oatgrass - Danthonia Intermedia Vasey
- Timberland Blue-eyed Grass - Sisyrinchium Longipes (E.P. Bicknell) Kearney & Peebles
- Timberline Beardtongue - Penstemon Davidsonii Greene var. praeteritus Cronquist
- Timberline Bluegrass - Poa Glauca Vahl ssp. rupicola (Nash ex Rydb.) W.A. Weber
- Timberline Sagebrush - Artemisia Rothrockii A. Gray
- Timberline Willow - Salix Rotundifolia Trautv. ssp. dodgeana (Rydb.) Argus
- Timmia Austriaca Hedw. var. arctica (Lindb.) Arnell
- Timmia Bavarica Hessl.
- Timmia Comata Lindb. & Arnell
- Timmia Megapolitana Hedw. ssp. bavarica (Hessl.) Brass.
- Timmia Moss - Timmia Hedw.
- Timmia Moss - Timmia Megapolitana Hedw.
- Timmia Moss - Timmia Megapolitana Hedw. var. megapolitana
- Timmia Norvegica J.E. Zetterst. var. comata (Lindb. & Arnell) H.A. Crum
- Timmia Norvegica J.E. Zetterst. var. crassiretis Hess.
- Timmiella Flexiseta sensu Grout
- Timmiella Flexiseta sensu Grout var. vancouveriensis (Broth.) Grout
- Timmiella Moss - Timmiella (de Not.) Limpr.
- Timmiella Moss - Timmiella Anomala Bruch & Schimp.
- Timmiella Moss - Timmiella Crassinervis (Hampe) L.F. Koch
- Timonius Dc.
- Timonius Ledermannii Valeton
- Timonius Nitidus (Bartlett ex DC.) Fernald-Vill.
- Timopheev's Wheat - Triticum Timopheevii (Zhuk.) Zhuk.
- Timor Allophylus - Allophylus Timoriensis (DC.) Blume
- Timor Ryssopterys - Stigmaphyllon Timoriense (DC.) C.E. Anderson
- Timothy Canarygrass - Phalaris Angusta Nees ex Trin.
- Timothy - Phleum L.
- Timothy - Phleum Pratense L.
- Tinantia - Tinantia Scheidw.
- Tinged Sedge - Carex Tincta (Fernald) Fernald
- Tingiringi Gum - Eucalyptus Glaucescens Maiden & Blakely
- Tiniaria Cilinodis (Michx.) Small
- Tiniaria Convolvulus (L.) Webb & Moq.
- Tiniaria Cristata (Engelm. & A. Gray) Small
- Tiniaria Dumetorum (L.) Opiz
- Tiniaria Scandens (L.) Small
- Tinker's Penny - Hypericum Anagalloides Cham. & Schltdl.
- Tinted Woodland Spurge - Euphorbia Commutata Engelm. ex A. Gray
- Tiny Bladderwort - Utricularia Pusilla Vahl
- Tiny Bluet - Houstonia Pusilla Schoepf
- Tiny Bristle Fern - Trichomanes Minutum Blume
- Tiny Milkwort - Polygala Smallii R.R. Sm. & Ward
- Tiny Mousetail - Myosurus Minimus L.
- Tiny Orchid - Lepanthopsis Melanantha (Rchb. f.) Ames
- Tiny Pea - Lathyrus Pusillus Elliott
- Tiny Purslane - Portulaca Minuta Correll
- Tiny Pygmydaisy - Pentachaeta Alsinoides Greene
- Tiny Trumpet - Collomia Linearis Nutt.
- Tiny Vetch - Vicia Hirsuta (L.) Gray
- Tinygland Didymoplexis - Didymoplexis Micradenia (Rchb. f.) Hemsl.
- Tinypetal Waxweed - Cuphea Micrantha Kunth
- Tinytim - Geocarpon Minimum Mack.
- Tioga Gentian - Gentiana Newberryi A. Gray var. tiogana (A. Heller) J. Pringle
- Tioga Pass Sedge - Carex Tiogana D.W. Taylor & J.D. Mastrog.
- Tipa - Tipuana Tipu (Benth.) Kuntze
- Tiplant - Cordyline Fruticosa (L.) A. Chev
- Tipuana Benth.
- Tipularia - Tipularia Nutt.
- Tipularia Unifolia Britton, Sterns & Poggenb.
- Tiquilia Brevifolia Nutt. ex Torr. var. plicata Torr.
- Tiquiliopsis Palmeri (A. Gray) Rydb.
- Tissa Canadensis (Pers.) Britton
- Tissa Clevelandii Greene
- Tissa Luteola Greene
- Tissa Marina (L.) Britton
- Tissa Rubra (L.) Britton
- Tissa Tenuis Greene
- Tissue Sedge - Carex Hyalina Boott
- Tissueleaf Hawthorn - Crataegus Membranacea Sarg.
- Tithonia Argophylla D.C. Eaton
- Tithonia Speciosa (Hook.) Griseb.
- Tithonia - Tithonia Desf. ex Juss.
- Tithymalopsis Apocynifolia (Small) Small
- Tithymalopsis Arundelana (Bartlett) Small
- Tithymalopsis Corollata (L.) Klotzsch
- Tithymalopsis Curtisii (Engelm.) Small
- Tithymalopsis Discoidalis (Chapm.) Small
- Tithymalopsis Eriogonoides Small
- Tithymalopsis Exserta Small
- Tithymalopsis Gracilis (Boiss.) Small
- Tithymalopsis Ipecacuanhae (L.) Small
- Tithymalopsis Marilandica (Greene) Small
- Tithymalopsis Mercurialina (Michx.) Small
- Tithymalopsis Olivacea Small
- Tithymalopsis Paniculata (Boiss.) Small
- Tithymalopsis Polyphylla (Engelm. ex Holz.) Small
- Tithymalopsis Strictior (Holz.) Wooton & Standl.
- Tithymalopsis Zinniiflora (Small) Small
- Tithymalus Arkansanus (Engelm. & A. Gray) Klotzsch & Garcke
- Tithymalus Austrinus Small
- Tithymalus Brachycera (Engelm.) Small
- Tithymalus Chamaesula (Boiss.) Wooton & Standl.
- Tithymalus Commutatus (Engelm. ex A. Gray) Klotzsch & Garcke
- Tithymalus Crenulatus (Engelm.) A. Heller
- Tithymalus Cyparissias (L.) Hill
- Tithymalus Darlingtonii (A. Gray) Small
- Tithymalus Esula (L.) Hill
- Tithymalus Falcatus (L.) Klotzsch & Garcke
- Tithymalus Helioscopius (L.) Hill
- Tithymalus Incisa (Engelm.) J.B.S. Norton
- Tithymalus Incisa (Engelm.) J.B.S. Norton var. mollis J.B.S. Norton
- Tithymalus Lathyris (L.) Hill
- Tithymalus Lucidus (Waldst. & Kit.) Klotzsch & Garcke
- Tithymalus Missouriensis (J.B.S. Norton) Small
- Tithymalus Montanus (Engelm.) Small
- Tithymalus Myrsinites (L.) Hill
- Tithymalus Obtusatus (Pursh) Klotzsch & Garcke
- Tithymalus Peplus (L.) Hill
- Tithymalus Platyphyllos (L.) Hill
- Tithymalus Robustus (Engelm.) Small
- Tithymalus Smallii (Millsp.) Small
- Tithymalus Spathulatus (Lam.) W.A. Weber
- Tithymalus Tetraporus (Engelm.) Small
- Tithymalus Texanus Millsp. ex A. Heller
- Tithymalus Uralensis (Fisch. ex Link) Prokhanov
- Titi - Cyrilla Garden ex L.
- Tium Drummondii (Douglas ex Hook.) Rydb.
- Tium Michauxii (Kuntze) Rydb.
- To-tsubaki - Camellia Reticulata Lindl.
- Toad Rush - Juncus Bufonius L.
- Toad Rush - Juncus Bufonius L. var. bufonius
- Toad Rush - Juncus Bufonius L. var. congestus Wahlenb.
- Toad Rush - Juncus Bufonius L. var. occidentalis F.J. Herm.
- Toadflax Beardtongue - Penstemon Linarioides A. Gray ssp. compactifolius D.D. Keck
- Toadflax Beardtongue - Penstemon Linarioides A. Gray ssp. linarioides
- Toadflax - Linaria Mill.
- Toadflax - Linaria ×sepium Allman
- Toadflax - Nuttallanthus D.a. Sutton
- Toadflax Penstemon - Penstemon Linarioides A. Gray
- Toadflax Penstemon - Penstemon Linarioides A. Gray ssp. coloradoensis (A. Nelson) D.D. Keck
- Toadlily - Tricyrtis Hirta (Thunb.) Hook.
- Toadshade - Trillium Sessile L.
- Toano Milkvetch - Astragalus Toanus M.E. Jones
- Toano Milkvetch - Astragalus Toanus M.E. Jones var. scidulus S.L. Welsh & N.D. Atwood
- Toano Milkvetch - Astragalus Toanus M.E. Jones var. toanus
- Tobacco - Nicotiana Excelsior (J.M. Black) J.M. Black
- Tobacco - Nicotiana Forgetiana Hort. ex Hemsl.
- Tobacco - Nicotiana Glutinosa L.
- Tobacco - Nicotiana L.
- Tobacco - Nicotiana Paniculata L.
- Tobacco - Nicotiana Tomentosa Ruiz & Pav.
- Tobacco - Nicotiana ×sanderae hort. ex W. Watson (pro sp.)
- Tobacco Root - Valeriana Edulis Nutt. ex Torr. & A. Gray
- Tobacco Root - Valeriana Edulis Nutt. ex Torr. & A. Gray var. ciliata (Torr. & A. Gray) Cronquis
- Tobacco Root - Valeriana Edulis Nutt. ex Torr. & A. Gray var. edulis
- Tobias' Saxifrage - Saxifraga Bryophora A. Gray var. tobiasiae J. Grimes & Packard
- Tobosagrass - Pleuraphis Mutica Buckley
- Toddy Palm - Borassus Flabellifer L. [excluded]
- Todsen's False Pennyroyal - Hedeoma Todsenii Irving
- Toetoe - Cortaderia Toetoe Zotov
- Tofieldia Glutinosa (Michx.) Pers.
- Tofieldia Glutinosa (Michx.) Pers. ssp. absona C.L. Hitchc.
- Tofieldia Glutinosa (Michx.) Pers. ssp. brevistyla C.L. Hitchc.
- Tofieldia Glutinosa (Michx.) Pers. ssp. glutinosa
- Tofieldia Glutinosa (Michx.) Pers. ssp. montana C.L. Hitchc.
- Tofieldia Glutinosa (Michx.) Pers. ssp. occidentalis (S. Watson) C.L. Hitchc.
- Tofieldia Glutinosa (Michx.) Pers. var. absona (C.L. Hitchc.) R.J. Davis
- Tofieldia Glutinosa (Michx.) Pers. var. brevistyla (C.L. Hitchc.) C.L. Hitchc.
- Tofieldia Glutinosa (Michx.) Pers. var. intermedia (Rydb.) B. Boivin
- Tofieldia Glutinosa (Michx.) Pers. var. montana (C.L. Hitchc.) R.J. Davis
- Tofieldia Glutinosa (Michx.) Pers. var. occidentalis (S. Watson) C.L. Hitchc.
- Tofieldia Occidentalis S. Watson
- Tofieldia Palustris auct. non Huds.
- Tofieldia Racemosa (Walter) Britton, Sterns & Poggenb.
- Tofieldia Racemosa (Walter) Britton, Sterns & Poggenb. var. glutinosa (Michx.) H.E.
- Tofieldia Tenuifolia (Michx.) Utech
- Tofieldia - Tofieldia Huds.
- Toft's Yucca - Yucca Angustissima Engelm. ex Trel. var. toftiae (S.L. Welsh) Reveal
- Toiyabe Buckwheat - Eriogonum Esmeraldense S. Watson var. toiyabense J.T. Howell
- Toiyabe Springparsley - Cymopterus Goodrichii S.L. Welsh & Neese
- Tolland County Blackberry - Rubus Saltuensis L.H. Bailey
- Tolmachevia Integrifolia (Raf.) Á. Löve & D. Löve
- Tolmie Star-tulip - Calochortus Tolmiei Hook. & Arn.
- Tolmie's Goldenrod - Solidago Missouriensis Nutt. var. tolmieana (A. Gray) Cronquist
- Tolmie's Onion - Allium Tolmiei (Hook.) Baker ex S. Watson
- Tolmie's Onion - Allium Tolmiei (Hook.) Baker ex S. Watson var. tolmiei
- Tolmie's Owl's-clover - Orthocarpus Tolmiei Hook. & Arn.
- Tolmie's Owl's-clover - Orthocarpus Tolmiei Hook. & Arn. ssp. tolmiei
- Tolmie's Penstemon - Penstemon Procerus Douglas ex Graham var. tolmiei (Hook.) Cronquist
- Tolmie's Saxifrage - Saxifraga Tolmiei Torr. & A. Gray
- Tolmiea Diplomenziesii Judd, Soltis & P.S. Soltis
- Tolmin's Orange Lichen - Caloplaca Tominii Savicz
- Tolpis Umbellata Bertol.
- Tolstead's Erigeron - Erigeron Pulchellus Michx. var. tolsteadii Cronquist
- Tolumnia Leiboldii auct. non (Rchb. f.) G.J. Braem
- Tomanthera Auriculata (Michx.) Raf.
- Tomanthera Densiflora (Benth.) Pennell
- Tomasellia Californica (Zahlbr.) R.C. Harris
- Tomasellia Eschweileri (Müll. Arg.) R.C. Harris
- Tomasellia Lactea (Ach.) R.C. Harris
- Tomasellia Lichen - Tomasellia A. Massal.
- Tomasellia Lichen - Tomasellia Difforme (Minks) ?, ined.?
- Tomasellia Macularis (Minks ex Willey) R.C. Harris
- Tomasellia Sparsella (Nyl.) R.C. Harris
- Tomato Fern - Lonchitis Hirsuta L.
- Tomcat Clover - Trifolium Willdenovii Spreng.
- Tomenthypnum Falcifolium (Renauld ex Nichols) Tuom., orth. var.
- Tomenthypnum Loeske, orth. var.
- Tomenthypnum Nitens (Hedw.) Loeske var. falcifolium Renauld ex Nichols, orth. var.
- Tomenthypnum Nitens (Hedw.) Loeske var. insigne (Milde) C.E.O. Jensen, orth. var.
- Tomenthypnum Nitens (Hedw.) Loeske var. involutum (Limpr.) C.E.O. Jensen, orth. var.
- Tomenthypnum Nitens (Hedw.) Loeske, orth. var.
- Tomenthypnum Paulianum (Grout) Broth. ex H. Rob., orth. var.
- Tomentose Burbark - Triumfetta Tomentosa Bojer
- Tomentose Gopherweed - Baptisia Lanceolata (Walter) Elliott var. tomentosa (Larisey) Isely
- Tomentose Groutiella Moss - Groutiella Tomentosa (Hornsch.) Wijk & Margad.
- Tomentose Mountain-avens - Dryas Drummondii Richardson ex Hook. var. tomentosa (Farr) L.O. Williams
- Tomentose Snow Lichen - Stereocaulon Sasakii Zahlbr. var. tomentosoides Lamb
- Tomentose Snow Lichen - Stereocaulon Tomentosum Fr.
- Tomentypnum Moss - Tomentypnum Loeske
- Tomentypnum Moss - Tomentypnum Nitens (Hedw.) Loeske
- Tomentypnum Nitens (Hedw.) Loeske var. falcifolium Renauld ex Nichols
- Tomentypnum Nitens (Hedw.) Loeske var. insigne (Milde) C.E.O. Jensen
- Tomentypnum Nitens (Hedw.) Loeske var. involutum (Limpr.) C.E.O. Jensen
- Tomentypnum Paulianum (Grout) Broth. ex H. Rob.
- Tomophyllum - Tomophyllum (e. Fourn.) Parris
- Tonella - Tonella Nutt. ex A. Gray
- Tongavine - Epipremnum Schott
- Tonglet's Cracked Lichen - Acarospora Tongleti Hue
- Tongue Fern - Pyrrosia Mirb.
- Tonguefern - Elaphoglossum Schott ex J. Sm.
- Tongueshape Bogmat - Wolffiella Lingulata (Hegelm.) Hegelm.
- Toninia Arctica Timdal
- Toninia Athallina (Hepp) Timdal
- Toninia Caeruleonigricans auct.
- Toninia Caulescens Anzi
- Toninia Conglomerata (Ach.) Boistel
- Toninia Kolax Poelt
- Toninia Lobulata (Sommerf.) Lynge
- Toninia Lutosa (Ach.) Timdal
- Toninia Opuntioides (Vill.) Timdal
- Toninia Pennina (Schaerer) Gyel.
- Toninia Philippea (Mont.) Timdal
- Toninia Physaroides (Opiz) Zahlbr.
- Toninia Ruginosa (Tuck.) Herre ssp. pacifica Timdal
- Toninia Ruginosa (Tuck.) Herre ssp. ruginosa
- Toninia Sculpturata (H. Magn.) Timdal
- Toninia Sedifolia (Scop.) Timdal
- Toninia Squarrosa (Ach.) Th. Fr.
- Toninia Subdiffracta Timdal
- Toninia Submexicana de Lesd.
- Toninia Superioris Timdal
- Toninia Tabacina auct.
- Toninia Talparum Timdal
- Toninia Tristis (Th. Fr.) Th. Fr. ssp. arizonica Timdal
- Toninia Tristis (Th. Fr.) Th. Fr. ssp. asiae-centralis (H. Magn.) Timdal
- Toninia Tristis (Th. Fr.) Th. Fr. ssp. canadensis Timdal
- Toninia Tristis (Th. Fr.) Th. Fr. ssp. scholanderi (Lynge) Timdal
- Toninia Tristis (Th. Fr.) Th. Fr. ssp. tristis
- Toninia Verrucarioides (Nyl.) Timdal
- Toninia Weberi Timdal
- Tonka Bean - Dipteryx Odorata (Aubl.) Willd.
- Tonkin Cane - Arundinaria Amabilis McClure
- Tonopah Milkvetch - Astragalus Pseudiodanthus Barneby
- Tontanea Herbacea (Aubl.) Standl.
- Tonto Basin Century Plant - Agave Delamateri W.C. Hodgson & L. Slauson
- Toona Australis (F. Muell.) Harms
- Toothache Grass - Ctenium Aromaticum (Walter) Alph. Wood
- Toothache Grass - Ctenium Panzer
- Toothed Brake - Pteris Denticulata Sw.
- Toothed Bristle Fern - Trichomanes Dentatum Bosch
- Toothed Calicoflower - Downingia Cuspidata (Greene) Greene ex Jeps.
- Toothed Clubmoss - Huperzia Erosa Beitel & W.H. Wagner
- Toothed Clubmoss - Huperzia Serrata (Thunb.) Trevis.
- Toothed Dock - Rumex Dentatus L.
- Toothed Five Eyes - Chamaesaracha Crenata Rydb.
- Toothed Flatsedge - Cyperus Dentatus Torr.
- Toothed Haresfoot Fern - Davallia Denticulata (Burm. f.) Mett. ex Kuhn var. denticulata
- Toothed Latticevein Fern - Thelypteris Serrata (Cav.) Alston
- Toothed Midsorus Fern - Blechnum Serrulatum Rich.
- Toothed Onion - Allium Denticulatum (Ownbey & Aase) McNeal
- Toothed Owl's-clover - Orthocarpus Cuspidatus Greene
- Toothed Phascum Moss - Phascum Cuspidatum Hedw.
- Toothed Plagiomnium Moss - Plagiomnium Cuspidatum (Hedw.) T. Kop.
- Toothed Plagiothecium Moss - Plagiothecium Denticulatum (Hedw.) Schimp.
- Toothed Pogonatum Moss - Pogonatum Dentatum (Brid.) Brid.
- Toothed Skin Lichen - Leptogium Denticulatum Tuck.
- Toothed Snailfern - Cochlidium Serrulatum (Sw.) Bishop
- Toothed Sphagnum - Sphagnum Cuspidatum Ehrh. ex Hoffm.
- Toothed Spiderflower - Cleome Serrata Jacq.
- Toothed Spleenwort - Asplenium Trichomanes-dentatum L.
- Toothed Spurge - Euphorbia Dentata Michx.
- Toothed Spurge - Euphorbia Dentata Michx. var. dentata
- Toothed Spurge - Euphorbia Dentata Michx. var. lasiocarpa Boiss.
- Toothed Surfgrass - Phyllospadix Serrulatus Rupr. ex Asch.
- Toothed Whitetop Aster - Sericocarpus Asteroides (L.) Britton, Sterns & Poggenb.
- Toothed Willow Dock - Rumex Salicifolius Weinm. var. denticulatus Torr.
- Toothedleaf Nitrogen Moss - Tetraplodon Angustatus (Hedw.) Bruch & Schimp.
- Toothedthread - Odontonema Nees
- Toothleaf Cyrtandra - Cyrtandra Halawensis Rock
- Toothleaf Goldeneye - Viguiera Dentata (Cav.) Spreng.
- Toothleaf Goldeneye - Viguiera Dentata (Cav.) Spreng. var. dentata
- Toothleaf Goldeneye - Viguiera Dentata (Cav.) Spreng. var. lancifolia S.F. Blake
- Toothleaf - Stillingia Garden ex L.
- Toothleaf Taxiphyllum Moss - Taxiphyllum Cuspidifolium (Cardot) Z. Iwats.
- Toothpetal Bog Orchid - Habenaria Odontopetala Rchb. f.
- Toothpetal Monkeyflower - Mimulus Dentilobus B.L. Rob. & Fernald
- Toothpickweed - Ammi Visnaga (L.) Lam.
- Top Cactus - Echinomastus Gautii (L.D. Benson) Mosco & Zanovello
- Topal Holly - Ilex ×attenuata Ashe
- Topeka Purple Coneflower - Echinacea Atrorubens Nutt.
- Topelia Lichen - Topelia Aperiens P.M. Jørg. & Vezda
- Topelia Lichen - Topelia P.m. Jørg. & Vezda
- Toquima Milkvetch - Astragalus Toquimanus Barneby
- Torch Tree - Ixora Pavetta Andrews
- Torch-ginger - Etlingera Elatior (Jack) R.M. Sm.
- Torchwood - Amyris P. Br.
- Tordylium - Tordylium L.
- Torenia Crustacea (L.) Cham. & Schltdl.
- Torenia Glabra Osbeck
- Torenia Polygonoides Benth.
- Torenia - Torenia L.
- Torhleaf Goldeneye - Viguiera Laciniata A. Gray
- Toria - Brassica Rapa L. var. dichotoma (Roxb. ex Fleming) Kitam.
- Torilis Arvensis (Huds.) Link ssp. purpurea (Ten.) Hayek
- Torilis Heterophylla Guss.
- Torilis Purpurea (Ten.) Guss.
- Toringo Crab - Malus Toringo (Siebold) Siebold ex de Vriese
- Tornabea Ephebea (Ach.) Kurok.
- Tornabea Osthagen
- Tornabea Scutellifera (With.) J.R. Laundon
- Tornillo - Prosopis Reptans Benth.
- Tornillo - Prosopis Reptans Benth. var. cinerascens (A. Gray) Burkart
- Torpedo Grass - Panicum Repens L.
- Torralbasia - Torralbasia Krug & Urb.
- Torresia Odorata (L.) Hitchc.
- Torrey Maple - Acer Glabrum Torr. var. torreyi (Greene) Smiley
- Torrey Pine - Pinus Torreyana Parry ex Carrière
- Torrey Pine - Pinus Torreyana Parry ex Carrière ssp. torreyana
- Torrey Wolfberry - Lycium Torreyi A. Gray
- Torrey's Amaranthus - Amaranthus Torreyi (A. Gray) Benth. ex S. Watson
- Torrey's Beaksedge - Rhynchospora Torreyana A. Gray
- Torrey's Blazingstar - Mentzelia Torreyi A. Gray
- Torrey's Blazingstar - Mentzelia Torreyi A. Gray var. acerosa (M.E. Jones) Barneby
- Torrey's Blazingstar - Mentzelia Torreyi A. Gray var. torreyi
- Torrey's Blue Eyed Mary - Collinsia Torreyi A. Gray
- Torrey's Blue Eyed Mary - Collinsia Torreyi A. Gray var. brevicarinata Newsom
- Torrey's Blue Eyed Mary - Collinsia Torreyi A. Gray var. latifolia Newsom
- Torrey's Blue Eyed Mary - Collinsia Torreyi A. Gray var. torreyi
- Torrey's Bulrush - Schoenoplectus Torreyi (Olney) Palla
- Torrey's Craglily - Echeandia Flavescens (Schult. & Schult. f.) Cruden
- Torrey's Croton - Croton Incanus Kunth
- Torrey's Cryptantha - Cryptantha Torreyana (A. Gray) Greene
- Torrey's Desertdandelion - Malacothrix Torreyi A. Gray
- Torrey's Four-nerve Daisy - Tetraneuris Torreyana (Nutt.) Greene
- Torrey's Jointfir - Ephedra Torreyana S. Watson
- Torrey's Jointfir - Ephedra Torreyana S. Watson var. powelliorum T. Wendt
- Torrey's Jointfir - Ephedra Torreyana S. Watson var. torreyana
- Torrey's Melicgrass - Melica Torreyana Scribn.
- Torrey's Milkvetch - Astragalus Calycosus Torr. ex S. Watson
- Torrey's Milkvetch - Astragalus Calycosus Torr. ex S. Watson var. calycosus
- Torrey's Milkvetch - Astragalus Calycosus Torr. ex S. Watson var. monophyllidius (Rydb.) Barneby
- Torrey's Milkvetch - Astragalus Calycosus Torr. ex S. Watson var. scaposus (A. Gray) M.E. Jones
- Torrey's Monkeyflower - Mimulus Torreyi A. Gray
- Torrey's Mountainmint - Pycnanthemum Torrei Benth.
- Torrey's Pea - Lathyrus Torreyi A. Gray
- Torrey's Penstemon - Penstemon Barbatus (Cav.) Roth ssp. torreyi (Benth.) D.D. Keck
- Torrey's Popcornflower - Plagiobothrys Torreyi (A. Gray) A. Gray
- Torrey's Popcornflower - Plagiobothrys Torreyi (A. Gray) A. Gray var. diffusus (Greene) I.M. Johnst.
- Torrey's Popcornflower - Plagiobothrys Torreyi (A. Gray) A. Gray var. torreyi
- Torrey's Rush - Juncus Torreyi Coville
- Torrey's Saltbush - Atriplex Torreyi (S. Watson) S. Watson
- Torrey's Sedge - Carex Torreyi Tuck.
- Torrey's Sphagnum - Sphagnum Torreyanum Sull.
- Torrey's Surfgrass - Phyllospadix Torreyi S. Watson
- Torrey's Tievine - Ipomoea Cordatotriloba Dennst. var. torreyana (A. Gray) D. Austin
- Torrey's Willowherb - Epilobium Torreyi (S. Watson) Hoch & P.H. Raven
- Torrey's Wrightwort - Carlowrightia Torreyana Wassh.
- Torrey's Yucca - Yucca Torreyi Shafer
- Torreya - Torreya Arn.
- Torreyochloa Fernaldii (Hitchc.) Church
- Torreyochloa Pauciflora (J. Presl) Church
- Torreyochloa Pauciflora (J. Presl) Church var. holmii (Beal) Roy L. Taylor & MacBryde
- Torreyochloa Pauciflora (J. Presl) Church var. microtheca (Buckley) Roy L. Taylor & MacB
- Torrid Panicgrass - Panicum Torridum Gaudich.
- Torrid Rim Lichen - Lecanora Torrida Vain.
- Torrubia Bracei Britton
- Torrubia Discolor (Spreng.) Britton
- Torrubia Floridana (Britton ex Small) Britton
- Torrubia Fragrans (Dum. Cours.) Standl.
- Torrubia Globosa Small
- Torrubia Longifolia (Heimerl) Britton
- Torrubia Obtusata (Jacq.) Britton
- Tortella Caespitosa (Schwägr.) Limpr.
- Tortella Inclinatula (Müll. Hal. & Kindb.) Broth.
- Tortella Moss - Tortella (lindb.) Limpr.
- Tortella Moss - Tortella Flavovirens (Bruch.) Broth.
- Tortella Moss - Tortella Humilis (Hedw.) Jenn.
- Tortella Moss - Tortella Inclinata (R. Hedw.) Limpr.
- Tortella Moss - Tortella Rigens Alb.
- Tortella Moss - Tortella Tortelloides (S.W. Greene) H. Rob.
- Tortipes Amplexifolius (L.) Small
- Tortoise Shell Bamboo - Phyllostachys Edulis (Carrière) J. Houz.
- Tortoiseshell Bamboo - Phyllostachys Heterocycla (Carrière) Matsum.
- Tortugo Prieto - Ravenia Urbanii Engl. ex Urb.
- Tortula Agraria (Hedw.) P. Beauv.
- Tortula Alpina (Milde) De Not. var. inermis (Milde) De Not.
- Tortula Aurea E.B. Bartram
- Tortula Bistratosa Flow.
- Tortula Caroliniana A.L. Andrews
- Tortula Desertorum Broth.
- Tortula Hirsuta Vent.
- Tortula Intermedia (Brid.) De Not.
- Tortula Laevipila (Brid.) Schwägr. var. pagorum Husn.
- Tortula Laevipila (Brid.) Schwägr. var. propagulifera Lindb.
- Tortula Laevipila (Brid.) Schwägr. var. wachteri Barkm.
- Tortula Moss - Tortula Amphidiacea (Müll. Hal.) Broth.
- Tortula Moss - Tortula Amplexa (Lesq.) Steere
- Tortula Moss - Tortula Brevipes (Lesq.) Broth.
- Tortula Moss - Tortula Caninervis (Mitt.) Broth.
- Tortula Moss - Tortula Chisosa Magill, Delgad. & L.R. Stark
- Tortula Moss - Tortula Hedw.
- Tortula Moss - Tortula Inermis (Brid.) Mont.
- Tortula Moss - Tortula Laevipila (Brid.) Schwägr.
- Tortula Moss - Tortula Laevipila (Brid.) Schwägr. var. laevipila
- Tortula Moss - Tortula Laevipila (Brid.) Schwägr. var. meridionalis (Schimp.) Wijk & Margad.
- Tortula Moss - Tortula Muralis Hedw.
- Tortula Moss - Tortula Pagorum (Milde) De Not.
- Tortula Moss - Tortula Papillosissima (Copp.) Broth.
- Tortula Moss - Tortula Princeps De Not.
- Tortula Moss - Tortula Rhizophylla (Sak.) Z. Iwats. & K. Saito
- Tortula Moss - Tortula Ruralis (Hedw.) G. Gaertn., B. Mey. & Scherb.
- Tortula Moss - Tortula Subulata Hedw.
- Tortula Moss - Tortula Virescens (De Not.) De Not.
- Tortula Obtusifolia (Schwägr.) Mathieu
- Tortula Propagulosa Sharp
- Tortula Reflexa Brid.
- Tortula Ruraliformis (Besch.) Ingh.
- Tortula Ruralis (Hedw.) G. Gaertn., B. Mey. & Scherb. var. crinita De Not.
- Tortula Ruralis (Hedw.) G. Gaertn., B. Mey. & Scherb. var. hirsuta (Vent.) Par.
- Tortula Subulata Hedw. var. angustata (Schimp.) Lindb.
- Tortula Vectensis Warb. & Crundw.
- Tortula Williamsii E.B. Bartram
- Tortured Chalice Lichen - Endocarpon Tortuosum Herre
- Tortured Horsehair Lichen - Bryoria Tortuosa (G. Merr.) Brodo & D. Hawksw.
- Tortured Tortella Moss - Tortella Tortuosa (Hedw.) Limpr.
- Torularia Arctica (Böcher) Á. Löve & D. Löve
- Torularia Humilis (C.A. Mey.) O.E. Schulz
- Torularia Humilis (C.A. Mey.) O.E. Schulz ssp. arctica Böcher
- Torulinium Confertum Desv. ex Ham.
- Torulinium Eggersii (Boeckeler) C.B. Clarke
- Torulinium Filiforme (Sw.) C.B. Clarke
- Torulinium Odoratum (L.) S. Hooper
- Torulinium Odoratum (L.) S. Hooper ssp. auriculatum (Nees & Meyen ex Kunth) T. Koyam
- Totara - Podocarpus Totara G. Bennett ex D. Don
- Touch-me-not - Impatiens L.
- Touchardia Angusta H. St. John
- Touchardia - Touchardia Gaudich.
- Tough Bully - Sideroxylon Tenax L.
- Toughleaf Dogwood - Cornus Asperifolia Michx.
- Toughleaf Iris - Iris Tenax Douglas ex Lindl.
- Toughleaf Iris - Iris Tenax Douglas ex Lindl. ssp. tenax
- Toumey Oak - Quercus Toumeyi Sarg.
- Toumey's Century Plant - Agave Toumeyana Trel. ex Standl.
- Toumey's Century Plant - Agave Toumeyana Trel. ex Standl. var. bella Breitung
- Toumey's Century Plant - Agave Toumeyana Trel. ex Standl. var. toumeyana
- Toumey's Groundsel - Packera Neomexicana (A. Gray) W.A. Weber & Á. Löve var. toumeyi (Greene) D.K. Trock
- Toumey's Sundrops - Calylophus Toumeyi (Small) Towner
- Toumeya Papyracantha (Engelm.) Britton & Rose
- Touret's Scleropodium Moss - Scleropodium Touretii (Brid.) L.F. Koch
- Touret's Scleropodium Moss - Scleropodium Touretii (Brid.) L.F. Koch var. colpophyllum (Sull.) E. Lawton ex H.A. Cr
- Touret's Scleropodium Moss - Scleropodium Touretii (Brid.) L.F. Koch var. touretii
- Touristplant - Dimorphocarpa Wislizeni (Engelm.) Rollins
- Tournefort's Gundelia - Gundelia Tournefortii L.
- Tournefortia Argentea L. f.
- Tournefortia Gnaphalodes (L.) R. Br. ex Roem. & Schult.
- Tournefortia Microphylla Bertol. ex Spreng.
- Tournefortia Peruviana Poir. p.p.
- Tournefortia Poliochros Spreng.
- Tournefortia Sibirica L.
- Tovara Virginiana (L.) Raf.
- Tovara Virginiana (L.) Raf. var. glaberrima Fernald
- Tovaria Trifolia (L.) Neck. ex Baker
- Tower Rockcress - Arabis Glabra (L.) Bernh.
- Towering Jacob's-ladder - Polemonium Foliosissimum A. Gray
- Towering Jacob's-ladder - Polemonium Foliosissimum A. Gray var. foliosissimum
- Towering Jacob's-ladder - Polemonium Foliosissimum A. Gray var. molle (Greene) Anway
- Towering Lousewort - Pedicularis Bracteosa Benth. var. flavida (Pennell) Cronquist
- Towering Lousewort - Pedicularis Bracteosa Benth. var. pachyrhiza (Pennell) Cronquist
- Townsend Daisy - Townsendia Hook.
- Townsendia Anomala Heiser
- Townsendia Arizonica A. Gray
- Townsendia Florifer (Hook.) A. Gray var. watsonii (A. Gray) Cronquist
- Townsendia Florifera (Hook.) A. Gray var. watsonii (A. Gray) Cronquist, database arti
- Townsendia Florifera (Hook.) A. Gray, database artifact
- Townsendia Intermedia Rydb.
- Townsendia Jonesii (Beaman) Reveal var. lutea S.L. Welsh
- Townsendia Mensana M.E. Jones var. jonesii Beaman
- Townsendia Minima Eastw.
- Townsendia Montana M.E. Jones
- Townsendia Montana M.E. Jones var. caelilinensis S.L. Welsh
- Townsendia Montana M.E. Jones var. minima (Eastw.) Beaman
- Townsendia Pinetorum Greene ex A. Nelson
- Townsendia Sericea Hook.
- Townsendia Sericea Hook. var. leptotes A. Gray
- Townsendia Vreelandii Rydb.
- Townsendia Wrightii (A. Gray) A. Gray
- Townsville Stylo - Stylosanthes Humilis Kunth
- Toxicodendron Altissimum Mill.
- Toxicodendron Crenatum Mill., nom. utique rej.
- Toxicodendron Desertorum Lunell
- Toxicodendron Quercifolium (Michx.) Greene
- Toxicodendron Radicans (L.) Kuntze ssp. diversilobum (Torr. & A. Gray) Thorne
- Toxicodendron Radicans (L.) Kuntze var. divaricatum (Greene) F.A. Barkley
- Toxicodendron Radicans (L.) Kuntze var. eximium (Greene) F.A. Barkley
- Toxicodendron Radicans (L.) Kuntze var. negundo (Greene) Reveal
- Toxicodendron Radicans (L.) Kuntze var. pubens (Engelm. ex S. Watson) Reveal
- Toxicodendron Radicans (L.) Kuntze var. rydbergii (Small ex Rydb.) Erskine
- Toxicodendron Radicans (L.) Kuntze var. verrucosum (Scheele) F.A. Barkley
- Toxicodendron Toxicarium (Salisb.) Gillis
- Toxicodendron Toxicodendron (L.) Britton, nom. inval.
- Toxicodendron Volubile Mill., nom. utique rej.
- Toxicodendron Vulgare Mill.
- Toxicoscordion Fontanum (Eastw.) Zomlefer & Judd
- Toxicoscordion Gramineum (Rydb.) Rydb.
- Toxicoscordion Micranthum (Eastw.) Heller
- Toxicoscordion Micranthus (Eastw.) A. Heller
- Toxicoscordion Nuttallii (A. Gray) Rydb.
- Toxicoscordion Paniculatum (Nutt.) Rydb.
- Toxicoscordion Venenosum (S. Watson) Rydb.
- Toxylon Pomiferum Raf.
- Toyon - Heteromeles Arbutifolia (Lindl.) M. Roem.
- Toyon - Heteromeles Arbutifolia (Lindl.) M. Roem. var. arbutifolia
- Toyon - Heteromeles Arbutifolia (Lindl.) M. Roem. var. cerina (Jeps.) A.E. Murray
- Toyon - Heteromeles Arbutifolia (Lindl.) M. Roem. var. macrocarpa (Munz) Munz
- Toyon - Heteromeles M. Roem.
- Tozer's Epipterygium Moss - Epipterygium Tozeri (Grev.) Lindb.
- Tracadigash Mountain Alkaligrass - Puccinellia Laurentiana Fernald & Weath.
- Tracaulon Arifolium (L.) Raf.
- Tracaulon Sagittatum (L.) Small
- Tracaulon Sagittatum (L.) Small var. gracilentum (Fernald) C.F. Reed
- Trachelospermum - Trachelospermum Lem.
- Trachybryum Moss - Trachybryum (broth.) Schof.
- Trachybryum Moss - Trachybryum Megaptilum (Sull.) Schof.
- Trachycarpus Wagnerianus Becc. [excluded]
- Trachycystis Moss - Trachycystis Flagellaris (Sull. & Lesq.) Lindb.
- Trachycystis Moss - Trachycystis Lindb.
- Trachylobium Verrucosum (Gaertn.) Oliv.
- Trachynia Distachya (L.) Link
- Trachyphytum Gracile Nutt., nom. inval.
- Trachypogon Montufari (Kunth) Nees
- Trachypogon Rufus Nees
- Trachypogon Secundus (J. Presl) Scribn.
- Trachypus Nigrescens (Hedw.) Mitt.
- Trachyspermum Copticum (L.) Link
- Trachyxiphium Moss - Trachyxiphium Heteroicum (Cardot) W.R. Buck
- Trachyxiphium Moss - Trachyxiphium W.r. Buck
- Tracy's Beaksedge - Rhynchospora Tracyi Britton
- Tracy's Blacksnakeroot - Sanicula Tracyi Shan & Constance
- Tracy's Bluegrass - Poa Tracyi Vasey
- Tracy's Bluestem - Andropogon Tracyi Nash
- Tracy's Clarkia - Clarkia Gracilis (Piper) A. Nelson & J.F. Macbr. ssp. tracyi (Jeps.) Abdel-Hamee
- Tracy's Collomia - Collomia Tracyi H. Mason
- Tracy's Desertparsley - Lomatium Tracyi Mathias & Constance
- Tracy's Hawthorn - Crataegus Tracyi Ashe ex Eggl.
- Tracy's Larkspur - Delphinium Antoninum Eastw.
- Tracy's Lupine - Lupinus Tracyi Eastw.
- Tracy's Mistmaiden - Romanzoffia Tracyi Jeps.
- Tracy's Pea - Lathyrus Lanszwertii Kellogg var. tracyi (Bradshaw) Isely
- Tracy's Rush - Juncus Tracyi Rydb.
- Tracy's Silkgrass - Pityopsis Graminifolia (Michx.) Nutt. var. tracyi (Small) Semple
- Tracy's Sundew - Drosera Tracyi Macfarlane
- Tracy's Thistle - Cirsium Undulatum (Nutt.) Spreng. var. tracyi (Rydb.) S.L. Welsh
- Tracy's Willow - Salix Tracyi C.R. Ball
- Tracyanthus Angustifolius (Michx.) Small
- Tradescantella Floridana (S. Watson) Small
- Tradescantia Albiflora Kunth
- Tradescantia Anomala Torr.
- Tradescantia Australis Bush
- Tradescantia Bicolor L'Hér.
- Tradescantia Brevicaulis Raf.
- Tradescantia Canaliculata Raf.
- Tradescantia Congesta (Moench) D. Don
- Tradescantia Cordifolia Sw.
- Tradescantia Discolor L'Hér.
- Tradescantia Discolor Raf., non L'Hér.
- Tradescantia Eglandulosa Bush
- Tradescantia Elongata G. Mey.
- Tradescantia Foliosa Small
- Tradescantia Geniculata Jacq.
- Tradescantia Incarnata Small
- Tradescantia Leiandra Torr. var. brevifolia Torr.
- Tradescantia Longifolia Small
- Tradescantia Micrantha Torr.
- Tradescantia Monandra Sw.
- Tradescantia Montana Shuttlw. ex Britton
- Tradescantia Occidentalis (Britton) Smyth var. typica E.S. Anderson & Woodson
- Tradescantia Ohiensis Raf. var. foliosa (Small) MacRoberts
- Tradescantia Ohiensis Raf. var. paludosa (E.S. Anderson & Woodson) MacRoberts
- Tradescantia Pendula (Schinz) D.R. Hunt
- Tradescantia Pilosa Lehm.
- Tradescantia Reflexa Raf.
- Tradescantia Rosea Vent.
- Tradescantia Rosea Vent. var. graminea (Small) E.S. Anderson & Woodson
- Tradescantia Rosea Vent. var. ornata (Small) E.S. Anderson & Woodson
- Tradescantia Rupestris Raf.
- Tradescantia Scopulorum Rose
- Tradescantia Speciosa Salisb.
- Tradescantia Subaspera Ker Gawl. var. typica E.S. Anderson & Woodson
- Tradescantia Texana Bush
- Tradescantia Virginiana L. var. alba Hook. ex Raf.
- Tradescantia Virginiana L. var. barbata Raf.
- Tragia Angustifolia Nutt.
- Tragia Linearifolia Elliott
- Tragia Macrocarpa Willd.
- Tragia Nepetifolia Cav. var. leptophylla (Torr.) Shinners
- Tragia Nepetifolia Cav. var. ramosa (Torr.) Müll. Arg.
- Tragia Ramosa Torr. var. leptophylla Torr.
- Tragia Stylaris Müll. Arg.
- Tragia Urticifolia Michx. var. texana Shinners
- Tragiola Pilosa (Michx.) Small & Pennell
- Tragiola Pilosa (Michx.) Small & Pennell ssp. epilis (Pennell) Pennell
- Tragopogon Dubius Scop. ssp. major (Jacq.) Voll.
- Tragopogon Lamottei Rouy
- Tragopogon Major Jacq.
- Tragopogon Orientalis L.
- Tragopogon Pratensis L. ssp. orientalis (L.) Celak.
- Trailing Abutilon - Abutilon Megapotamicum (A. Spreng.) A. St.-Hil. & Naudin
- Trailing Arbutus - Epigaea L.
- Trailing Arbutus - Epigaea Repens L.
- Trailing Black Currant - Ribes Laxiflorum Pursh
- Trailing Buckbrush - Ceanothus Connivens Greene
- Trailing Crabgrass - Digitaria Radicosa (J. Presl) Miq.
- Trailing Fenugreek - Trigonella Procumbens (Besser) Rchb.
- Trailing Fleabane - Erigeron Flagellaris A. Gray
- Trailing Indigo - Indigofera Hendecaphylla Jacq.
- Trailing Krameria - Krameria Lanceolata Torr.
- Trailing Lespedeza - Lespedeza Procumbens Michx.
- Trailing Milkvine - Matelea Pubiflora (Decne.) Woodson
- Trailing Pearlwort - Sagina Decumbens (Elliott) Torr. & A. Gray
- Trailing Pearlwort - Sagina Decumbens (Elliott) Torr. & A. Gray ssp. decumbens
- Trailing Phlox - Phlox Nivalis Lodd. ex Sweet
- Trailing Phlox - Phlox Nivalis Lodd. ex Sweet ssp. nivalis
- Trailing Shrubverbena - Lantana Montevidensis (Spreng.) Briq.
- Trailing Snowberry - Symphoricarpos Hesperius G.N. Jones
- Trailing St. Johnswort - Hypericum Humifusum L.
- Trailing Wakerobin - Trillium Decumbens Harbison
- Trailing White Monkshood - Aconitum Reclinatum A. Gray
- Trailing Windmills - Allionia Incarnata L.
- Trailing Windmills - Allionia Incarnata L. var. incarnata
- Trailing Windmills - Allionia Incarnata L. var. nudata (Standl.) Munz
- Trailing Windmills - Allionia Incarnata L. var. villosa (Standl.) B.L. Turner
- Trailing Yellow Loosestrife - Lysimachia Radicans Hook.
- Trailplant - Adenocaulon Hook.
- Trampweed - Facelis Cass.
- Tranquil Goldenweed - Pyrrocoma Clementis Rydb.
- Tranquil Goldenweed - Pyrrocoma Clementis Rydb. var. clementis
- Tranquil Goldenweed - Pyrrocoma Clementis Rydb. var. villosa (Rydb.) Mayes ex G. Brown & Keil
- Trans-pecos Amaranth - Amaranthus Obcordatus (A. Gray) Standl.
- Trans-pecos Ayenia - Ayenia Filiformis S. Watson
- Trans-pecos Beargrass - Nolina Arenicola Correll
- Trans-pecos Beeblossom - Oenothera Arida W.L. Wagner & Hoch
- Trans-pecos Chickweed - Cerastium Axillare Correll
- Trans-pecos Cliffbrake - Pellaea Ternifolia (Cav.) Link
- Trans-pecos Cliffbrake - Pellaea Ternifolia (Cav.) Link ssp. ternifolia
- Trans-pecos Cliffbrake - Pellaea Ternifolia (Cav.) Link ssp. villosa Windham
- Trans-pecos Cress - Mancoa Pubens (A. Gray) Rollins
- Trans-pecos Croton - Croton Sancti-lazari Croizat
- Trans-pecos Cyclanthera - Cyclanthera Stenura G.L. Nesom
- Trans-pecos Desert Goldenrod - Xylothamia Triantha (S.F. Blake) G.L. Nesom
- Trans-pecos Dodder - Cuscuta Decipiens Yunck.
- Trans-pecos Drymary - Drymaria Laxiflora Benth.
- Trans-pecos False Clapdaisy - Pseudoclappia Arenaria Rydb.
- Trans-pecos False Mountainparsley - Pseudocymopterus Longiradiatus Mathias, Constance & W.L. Theobald
- Trans-pecos Five Eyes - Chamaesaracha Villosa Rydb.
- Trans-pecos Giant Hyssop - Agastache Breviflora (A. Gray) Epling
- Trans-pecos Honeysweet - Tidestromia Gemmata I.M. Johnst.
- Trans-pecos Horseweed - Laennecia Filaginoides DC.
- Trans-pecos Indian Paintbrush - Castilleja Nervata Eastw.
- Trans-pecos Indian Parsley - Aletes Filifolius Mathias, Constance & W.L. Theobald
- Trans-pecos Maidenbush - Phyllanthopsis Arida (Warnock & M.C. Johnst.) Voronts. & Petra Hoffm.
- Trans-pecos Milkvine - Matelea Texensis Correll
- Trans-pecos Mock Orange - Philadelphus Crinitus (C.L. Hitchc.) Hu
- Trans-pecos Morning-glory - Ipomoea Cristulata Hallier f.
- Trans-pecos Poreleaf - Porophyllum Scoparium A. Gray
- Trans-pecos Sandwort - Arenaria Ludens Shinners
- Trans-pecos Sea Lavender - Limonium Limbatum Small
- Trans-pecos Senna - Senna Pilosior (B.L. Rob. ex J.F. Macbr.) Irwin & Barneby
- Trans-pecos Sotol - Dasylirion Heteracanthum I.M. Johnst.
- Trans-pecos Spiderwort - Tradescantia Brevifolia (Torr.) Rose
- Trans-pecos Stinkleaf - Nectouxia Formosa Kunth
- Trans-pecos Tansyaster - Psilactis Brevilingulata Sch. Bip. ex Hemsl.
- Trans-pecos Thimblehead - Hymenothrix Wislizeni A. Gray
- Trans-pecos Wrightwort - Carlowrightia Serpyllifolia A. Gray
- Transberingia Bursifolia (DC.) Al-Shehbaz & O'Kane
- Transcend Cup Lichen - Cladonia Transcendens (Vain.) Vain.
- Transmontane Gilia - Gilia Transmontana (H. Mason & A.D. Grant) A.D. Grant & V.E. Grant
- Transmontane Sand Verbena - Abronia Turbinata Torr. ex S. Watson
- Transparent Milkvetch - Astragalus Diaphanus Douglas ex Hook.
- Transvaal Daisy - Gerbera J.f. Gmel.
- Transverse Range Phacelia - Phacelia Exilis (A. Gray) G.L. Lee
- Trapa Bispinosa Roxb.
- Trapa Natans L. var. bispinosa (Roxb.) Makino
- Trapa Natans L. var. natans
- Trapelia Brujeriana (D. Dietr.) M. Choisy
- Trapelia Corticola Coppins & P. James
- Trapelia Torellii (Anzi) Hertel
- Trapeliopsis Aeneofusca (Flotow) Coppins & P. James
- Trapeliopsis Lichen - Trapeliopsis Flexuosa (Fr.) Coppins & P. James
- Trapeliopsis Lichen - Trapeliopsis Hertel & Gotth. Schneid.
- Trapeliopsis Lichen - Trapeliopsis Pseudogranulosa Coppins & P. James
- Trapeliopsis Lichen - Trapeliopsis Viridescens (Schrad.) Coppins & P. James
- Trask's Cryptantha - Cryptantha Traskiae I.M. Johnst.
- Trask's Island Broom - Lotus Dendroideus (Greene) Greene var. traskiae (Eastw. ex Noddin) Isely
- Trask's Milkvetch - Astragalus Traskiae Eastw.
- Traub's Rainlily - Cooperia Traubii Hayward
- Trautvetteria Grandis Nutt.
- Traveler's Delight - Apios Priceana B.L. Rob.
- Traveler's Tree - Ravenala Adans.
- Traveler's Tree - Ravenala Madagascariensis Sonnerat
- Traveler's-joy - Clematis Brachiata Thunb.
- Treadsoftly - Cnidoscolus Aconitifolius (Mill.) I.M. Johnst.
- Treasure-flower - Gazania Rigens (L.) Gaertn.
- Treasureflower - Gazania Linearis (Thunb.) Druce
- Trecul's Pricklyleaf - Thymophylla Tenuiloba (DC.) Small var. treculii (A. Gray) Strother
- Trecul's Toothleaf - Stillingia Treculiana (Müll. Arg.) I.M. Johnst.
- Treculia - Treculia Decne. ex Trec.
- Tree Aenium - Aeonium Arboreum (L.) Webb & Berthel.
- Tree Anemone - Carpenteria Californica Torr.
- Tree Anemone - Carpenteria Torr.
- Tree Blackberry - Rubus Probabilis L.H. Bailey
- Tree Brake - Pteris Arborea L.
- Tree Cactus - Pilosocereus Byles & Rowley
- Tree Cholla - Cylindropuntia Imbricata (Haw.) F.M. Knuth
- Tree Cholla - Cylindropuntia Imbricata (Haw.) F.M. Knuth var. argentea (Anthony) Backeb.
- Tree Cholla - Cylindropuntia Imbricata (Haw.) F.M. Knuth var. imbricata
- Tree Climacium Moss - Climacium Dendroides (Hedw.) F. Weber & D. Mohr
- Tree Cotton - Gossypium Arboreum L.
- Tree Crabseye Lichen - Ochrolechia Arborea (Kreyer) Almb.
- Tree Destroyer - Dendrophthora Eichl.
- Tree Fern - Dicksonia L'hér.
- Tree Groundpine - Lycopodium Dendroideum Michx.
- Tree Lavatera - Lavatera Olbia L.
- Tree Lavatera - Lavatera Thuringiaca L.
- Tree Limonium - Limonium Arborescens (Brouss.) Kuntze
- Tree Mallow - Lavatera Arborea L.
- Tree Mallow - Lavatera L.
- Tree Marigold - Tithonia Diversifolia (Hemsl.) A. Gray
- Tree Mat Homalothecium Moss - Homalothecium Fulgescens (Mitt. ex Müll. Hal.) E. Lawton
- Tree Morning Glory - Ipomoea Pauciflora M. Martens & Galeotti
- Tree Of Heaven - Ailanthus Altissima (Mill.) Swingle
- Tree Phaeographis - Phaeographis Dendritica (Ach.) Müll. Arg.
- Tree Polychidium Lichen - Polychidium Dendriscum (Nyl.) Henssen
- Tree Poppy - Dendromecon Benth.
- Tree Poppy - Dendromecon Rigida Benth.
- Tree Poppy - Dendromecon Rigida Benth. ssp. rhamnoides (Greene) Thorne
- Tree Poppy - Dendromecon Rigida Benth. ssp. rigida
- Tree Seaside Tansy - Borrichia Arborescens (L.) DC.
- Tree Shield Lichen - Heterodermia Dendritica (Pers.) Poelt
- Tree Snailfern - Cochlidium Seminudum (Willd.) Maxon
- Tree Spilonema Lichen - Spilonema Dendroides Henssen
- Tree Spurge - Euphorbia Dendroides L.
- Tree Stonecrop - Sedum Dendroideum Moc. & Sessé ex A. DC.
- Tree Tobacco - Nicotiana Glauca Graham
- Tree Tomato - Cyphomandra Betacea (Cav.) Sendtn.
- Treebine - Cissus L.
- Treecotton - Kokia Lewt.
- Treedaisy - Montanoa Hibiscifolia (Benth.) Standl.
- Treefern - Cyathea Nigricans Mett.
- Treefern - Cyathea Sm.
- Treelimb Clubmoss - Huperzia Polytrichoides (Kaulf.) Trevis.
- Treelover - Philodendron Lingulatum (L.) K. Koch
- Treemoss Bristle Fern - Trichomanes Krausii Hook. & Grev.
- Treetrunk Bristle Fern - Trichomanes Capillaceum L.
- Treetrunk Clubmoss - Huperzia Aqualupiana (Spring) Rothm.
- Treetrunk Cyanea - Cyanea Copelandii Rock
- Treetrunk Cyanea - Cyanea Copelandii Rock ssp. copelandii
- Treetrunk Cyanea - Cyanea Copelandii Rock ssp. haleakalaensis (H. St. John) Lammers
- Treetrunk Fern - Anetium Citrifolium (L.) Splitg.
- Treetrunk Fern - Anetium Splitg.
- Treetrunk Polypody - Polypodium Dulce Poir.
- Treetrunk Spleenwort - Asplenium Auriculatum Sw.
- Trefoil - Lotus L.
- Trelease's Beavertail Pricklypear - Opuntia Basilaris Engelm. & J.M. Bigelow var. treleasei (J.M. Coult.) J.M. Coult.
- Trelease's Century Plant - Agave Schottii Engelm. var. treleasei (Toumey) Kearney & Peebles
- Trelease's Draba - Draba Paysonii J.F. Macbr. var. treleasii (O.E. Schulz) C.L. Hitchc.
- Trelease's Hybrid Willowherb - Epilobium ×treleaseanum H. Lév.
- Trelease's Milkvetch - Astragalus Racemosus Pursh var. treleasei Ced. Porter
- Trema Floridana Britton
- Trema Micranthum (L.) Blume, orth. var.
- Trema Orientalis (L.) Blume var. viridis Lauterb., nom. inq.
- Trema - Trema Lour.
- Trematodon Moss - Trematodon Brevicollis Hoppe & Hornsch. ex Hornsch.
- Trematodon Moss - Trematodon Longicollis Michx.
- Trematodon Moss - Trematodon Michx.
- Trematolobelia Kohalaensis H. St. John
- Trematolobelia Lustrialis H. St. John
- Trematolobelia Macrostachys (Hook. & Arn.) Zahlbr. ex Rock var. kaalae (O. Deg.) E. Wimm.
- Trematolobelia Macrostachys (Hook. & Arn.) Zahlbr. var. haleakalaensis H. St. John
- Trematolobelia Rockii H. St. John var. hawaiiensis H. St. John
- Trematolobelia Sandwicensis O. Deg. var. kaalae O. Deg.
- Trembleya - Trembleya Dc.
- Tremella Cetrariicola Diederich & Coppins
- Tremella Cladoniae Diederich & M.S. Christ.
- Tremella Dendrographae Diederich & Tehler
- Tremella Everniae Diederich
- Tremella Haematommatis Diederich
- Tremella Harrisii Diederich
- Tremella Hypogymniae Diederich & M.S. Christ.
- Tremella Lichenicola Diederich
- Tremella Nephromatis Diederich
- Tremella Parmeliarum Diederich
- Tremella Pers.
- Tremella Pertusariae Diederich
- Tremella Phaeographinae Diederich & Aptroot
- Tremolecia Jurana (Schaerer) Hertel
- Tremolecia Micropsis (A. Massal.) Hertel
- Tremolecia Nivalis (Anzi) Hertel
- Trepocarpus - Trepocarpus Nutt. ex DC.
- Tres Cabezas - Psychotria Uliginosa Sw.
- Triadenum Longifolium Small
- Triadenum Petiolatum (Walter) Britton
- Triadenum Tubulosum (Walter) Gleason var. walteri (J.G. Gmel.) Cooperr.
- Triadenum Virginicum (L.) Raf. ssp. fraseri (Spach) J.M. Gillett
- Triadenum Virginicum (L.) Raf. var. fraseri (Spach) Cooperr.
- Triangle Bur Ragweed - Ambrosia Deltoidea (Torr.) Payne
- Triangle Cactus - Acanthocereus (engelm. ex A. Berger) Britton & Rose
- Triangle Cactus - Acanthocereus Tetragonus (L.) Humm.
- Triangle Orache - Atriplex Prostrata Bouchér ex DC.
- Triangle Waterfern - Ceratopteris Richardii Brongn.
- Triangleleaf Lipfern - Doryopteris Decipiens (Hook.) J. Sm.
- Trianglelobe Moonwort - Botrychium Ascendens W.H. Wagner
- Triangularfruit Sedge - Carex Triquetra Boott
- Trianthema - Trianthema L.
- Tribolium Echinatum (Thunb.) Renvoize
- Tribolium Hispidum (Thunb.) Desv.
- Tribolium - Tribolium Desv.
- Tribolium Uniolae (L. f.) Renvoize
- Tricardia - Tricardia Torr. ex S. Watson
- Tricera Citrifolia Willd.
- Tricera Vahlii (Baill.) Britton
- Tricerma Phyllanthoides (Benth.) Lundell
- Tricerma Texana (Lundell) Lundell
- Trichachne Affinis Swallen
- Trichachne Californica (Benth.) Chase
- Trichachne Eggersii (Hack.) Henr.
- Trichachne Hitchcockii (Chase) Chase
- Trichachne Insularis (L.) Nees
- Trichachne Nutans (L.) Baum
- Trichachne Patens Swallen
- Trichantha Ambigua (Urb.) Wiehler
- Tricharia Lichen - Tricharia Cretacea Vezda
- Tricharia Lichen - Tricharia Fée
- Tricharia Lichen - Tricharia Vezdae W.R. Buck
- Tricharia Melanothrix Fée
- Trichilia Emetica Vahl
- Trichilia - Trichilia P. Br.
- Trichilia - Trichilia Roka (Forssk.) Chiov.
- Trichiogramme Borneensis (Hook.) Kuhn
- Trichipteris Borinquena (Maxon) R. Tryon
- Trichipteris C. Presl
- Trichipteris Procera (Willd.) R. Tryon
- Trichipteris Pubescens (Baker) R. Tryon [excluded]
- Trichloris Mendocina (Phil.) Kurtz
- Trichocereus Auricolor Backeb.
- Trichocereus Callianthus F. Ritter
- Trichocereus Candicans (Gillies ex Salm-Dyck) Britton & Rose
- Trichocereus Grandiflorus Backeb.
- Trichocereus Pasacanus (F.A.C. Weber) Friedrich & G.D. Rowley
- Trichocereus Peruvianus Britton & Rose
- Trichocereus - Trichocereus (a. Berger) Riccob.
- Trichocereus Uyupampensis Backeb.
- Trichocolea Dumort., nom. cons.
- Trichocolea Tomentella (Ehrh.) Dumort.
- Trichocoronis Riparia (Greene) Greene
- Trichocoronis Wrightii (Torr. & A. Gray) A. Gray var. wrightii
- Trichodon Borealis R.S. Williams
- Trichodon Moss - Trichodon Cylindricus (Hedw.) Schimp.
- Trichodon Moss - Trichodon Cylindricus (Hedw.) Schimp. var. cylindricus
- Trichodon Moss - Trichodon Cylindricus (Hedw.) Schimp. var. oblongus (Lindb.) Podp.
- Trichodon Moss - Trichodon Schimp.
- Trichoglottis - Trichoglottis Blume
- Tricholaena Monachne (Trin.) Stapf & C.E. Hubb.
- Tricholaena Repens (Willd.) Hitchc.
- Tricholaena Rosea Nees
- Tricholaena Schrad.
- Tricholaena Teneriffae (L. f.) Link
- Tricholepis Nigrescens (Hedw.) Grout
- Tricholepis Nigrescens (Hedw.) Grout var. donnellii (Austin) Grout
- Trichomanes Baldwinii (D.C. Eaton) Copeland
- Trichomanes Beccarianum Ces.
- Trichomanes Boryanum Kunze
- Trichomanes Javanicum Blume var. javanicum
- Trichomanes Pusillum auct. non Sw.
- Trichomanes Saxifragoides C. Presl
- Trichomanes Sphenoides Kunze
- Trichophorum Caespitosum (L.) Hartm. var. callosum (Bigelow) Mohlenbr., orth. var.
- Trichophorum Caespitosum (L.) Hartm., orth. var.
- Trichophorum Palustre (L.) Farw. var. calvum (Torr.) House
- Trichophorum Pumilum (Vahl) Schinz & Thell. ssp. rollandii (Fernald) Roy L. Taylor &
- Trichophorum Pumilum (Vahl) Schinz & Thell. var. rollandii (Fernald) Hultén
- Trichophorum Rollandii (Fernald) Hultén
- Trichophorum Verecundum (Fernald) Mohlenbr.
- Trichophyllum Tenue (Willd.) Farw.
- Trichoptilium - Trichoptilium A. Gray
- Trichoramalina Lichen - Trichoramalina Crinita (Tuck.) Rundel & Bowler
- Trichoramalina Lichen - Trichoramalina Rundel & Bowler
- Trichosanthes - Trichosanthes L.
- Trichospermum Blume
- Trichospermum Richii (A. Gray) Seem.
- Trichostema Dichotomum L. var. lineare (Walter) Pursh
- Trichostema Dichotomum L. var. puberulum Fernald & Grisc.
- Trichostema Laxum A. Gray var. rubisepalum (Elmer) Jeps.
- Trichostema Lineare Walter
- Trichostema Pilosum Roth
- Trichostomopsis Australasiae (Hook. & Grev.) H. Rob. var. umbrosus (Müll. Hal.) R.H. Zander,
- Trichostomopsis Crispifolia Cardot
- Trichostomopsis Diaphanobasis (Cardot) Grout
- Trichostomopsis Fayae Grout
- Trichostomopsis Moss - Trichostomopsis Cardot
- Trichostomopsis Umbrosus (Müll. Hal.) H. Rob.
- Trichostomum Crispulum Bruch var. cucullatum (G. Roth) Podp.
- Trichostomum Cuspidatissimum Cardot & Thér.
- Trichostomum Cylindricum (Brid.) Müll. Hal.
- Trichostomum Jamaicense (Mitt.) A. Jaeger
- Trichostomum Mollissimum auct. Amer.
- Trichostomum Moss - Trichostomum Brachydontium Bruch
- Trichostomum Moss - Trichostomum Bruch
- Trichostomum Moss - Trichostomum Crispulum Bruch
- Trichostomum Moss - Trichostomum Molariforme R.H. Zander
- Trichostomum Moss - Trichostomum Sinaloense (E.B. Bartram) R.H. Zander
- Trichostomum Spirale Grout
- Trichostomum Tenuirostre (Hook. & Taylor) Lindb.
- Trichostomum Vancouveriense (Broth.) Kindb.
- Trichothelium Aeneum (Wallr.) R.C. Harris
- Trichothelium Cestrense (Michener) R.C. Harris
- Trichothelium Chloroticum (Ach.) R.C. Harris
- Trichothelium Crocynioides R.C. Harris
- Trichothelium Guentheri (Flotow) R.C. Harris
- Trichothelium Isidiatum R.C. Harris
- Trichothelium Lichen - Trichothelium Epiphyllum Müll. Arg.
- Trichothelium Lichen - Trichothelium Horridulum (Müll. Arg.) R. Sant.
- Trichothelium Lichen - Trichothelium Müll. Arg.
- Trichothelium Lineare (Leight.) R.C. Harris
- Trichothelium Nitidulum (Müll. Arg.) R.C. Harris
- Trichothelium Rhaphidospermum (Müll. Arg.) R.C. Harris
- Trichothelium Thaxteri (R. Sant.) R.C. Harris
- Triclinium Odoratum Raf.
- Triclisperma Paucifolia (Willd.) Nieuwl.
- Tricolor Daisy - Glebionis Carinatum (Schousb.) Tzvelev
- Tricolor Monkeyflower - Mimulus Tricolor Hartw. ex Lindl.
- Tricyrtis - Tricyrtis Wall.
- Tridax Accedens S.F. Blake
- Tridax - Tridax L.
- Tridens Brasiliensis (Nees ex Steud.) Parodi
- Tridens Chapmanii (Small) Chase
- Tridens Elongatus (Buckley) Nash
- Tridens Grandiflorus (Vasey) Wooton & Standl.
- Tridens Nealleyi (Vasey) Wooton & Standl.
- Tridens Oklahomensis (Featherly) Featherly
- Tridens Pilosus (Buckley) Hitchc.
- Tridens Pulchellus (Kunth) Hitchc.
- Tridens - Tridens Roem. & Schult.
- Tridens ×oklahomensis (Featherly) Featherly (pro sp.), database artifact
- Trident Maple - Acer Buergerianum Miq.
- Trientalis Americana Pursh
- Trientalis Arctica Fisch. ex Hook.
- Trientalis Europaea L. var. arctica (Fisch. ex Hook.) Ledeb.
- Trientalis Europaea L. var. latifolia (Hook.) Torr.
- Trientalis Latifolia Hook.
- Trifolium Affine C. Presl
- Trifolium Agrarium L., nom. utique rej.
- Trifolium Aitonii Rydb.
- Trifolium Albopurpureum Torr. & A. Gray var. albopurpureum
- Trifolium Albopurpureum Torr. & A. Gray var. dichotomum (Hook. & Arn.) Isely
- Trifolium Albopurpureum Torr. & A. Gray var. neolagopus (Loja.) McDermott
- Trifolium Albopurpureum Torr. & A. Gray var. olivaceum (Greene) Isely
- Trifolium Amphianthum Torr. & A. Gray
- Trifolium Amplectens Torr. & A. Gray
- Trifolium Amplectens Torr. & A. Gray var. hydrophilum (Greene) Jeps.
- Trifolium Amplectens Torr. & A. Gray var. truncatum (Greene) Jeps.
- Trifolium Andersonii A. Gray var. andersonii
- Trifolium Andersonii A. Gray var. beatleyae (J.M. Gillett) Isely
- Trifolium Andersonii A. Gray var. friscanum S.L. Welsh
- Trifolium Andersonii A. Gray var. monoense (Greene) Isely
- Trifolium Anemophilum Greene
- Trifolium Appendiculatum Loja.
- Trifolium Arcuatum Piper
- Trifolium Arizonicum Greene
- Trifolium Armenium Willd.
- Trifolium Arvense L. var. arvense
- Trifolium Arvense L. var. perpusillum DC.
- Trifolium Atrorubens (Greene) House
- Trifolium Baccarinii Chiov.
- Trifolium Badium Schreb.
- Trifolium Balansae Boiss.
- Trifolium Bicephalum Elmer
- Trifolium Bifidum A. Gray var. bifidum
- Trifolium Bifidum A. Gray var. decipiens Greene
- Trifolium Brachycalycinum (Katzn. & Morley) Katzn.
- Trifolium Bracteolatum Rydb.
- Trifolium Burchellianum Ser. var. johnstonii (Oliv.) J.B. Gillett
- Trifolium Campestre Schreb. var. minus (W.D.J. Koch) Kozuharov
- Trifolium Catalinae S. Watson
- Trifolium Caurinum Piper
- Trifolium Cherleri L.
- Trifolium Columbianum Greene
- Trifolium Columbianum Greene var. argillorum Jeps.
- Trifolium Columbianum Greene var. olivaceum (Greene) Jeps.
- Trifolium Compactum Post
- Trifolium Covillei House
- Trifolium Cryptopodium Steud. ex A. Rich.
- Trifolium Curvisepalum Tackh.
- Trifolium Dasyphyllum Torr. & A. Gray var. anemophilum (Greene) J.S. Martin ex Isely
- Trifolium Dasyphyllum Torr. & A. Gray var. stenolobum (Rydb.) McDermott
- Trifolium Dasyphyllum Torr. & A. Gray var. uintense (Rydb.) J.S. Martin ex Isely
- Trifolium Dasyphyllum Torr. & A. Gray var. uintense (Rydb.) S.L. Welsh
- Trifolium Dasyurum C. Presl
- Trifolium Depauperatum Desv. var. hydrophilum (Greene) J.S. Martin ex Isely
- Trifolium Depauperatum Desv. var. laciniatum (Greene) Jeps.
- Trifolium Depauperatum Desv. var. truncatum (Greene) McDermott ex Isely
- Trifolium Dichotomum Hook. & Arn. var. turbinatum Jeps.
- Trifolium Dichroanthum Boiss.
- Trifolium Echinatum M. Bieb. var. carmeli (Boiss.) Gibelli & Belli
- Trifolium Elegans Savi
- Trifolium Elmeri Greene
- Trifolium Eriocephalum Nutt. var. butleri Jeps.
- Trifolium Eriocephalum Nutt. var. cusickii (Piper) J.S. Martin
- Trifolium Eriocephalum Nutt. var. eriocephalum
- Trifolium Eriocephalum Nutt. var. harneyense (Howell) McDermott
- Trifolium Eriocephalum Nutt. var. piperi J.S. Martin
- Trifolium Eriocephalum Nutt. var. villiferum (House) J.S. Martin
- Trifolium Fendleri Greene
- Trifolium Fimbriatum Lindl.
- Trifolium Flavulum Greene
- Trifolium Fragiferum L. ssp. bonannii (C. Presl) Soják
- Trifolium Fruticans L.
- Trifolium Fucatum Lindl. var. gambelii (Nutt.) Jeps.
- Trifolium Fucatum Lindl. var. virescens (Greene) Jeps.
- Trifolium Gambelii Nutt.
- Trifolium Geminiflorum Greene
- Trifolium Gracilentum Torr. & A. Gray var. inconspicuum Fernald
- Trifolium Grayi Loja.
- Trifolium Gymnocarpon Nutt. var. lemmonii (S. Watson) McDermott
- Trifolium Gymnocarpon Nutt. var. plummerae (S. Watson) J.S. Martin
- Trifolium Gymnocarpon Nutt. var. subcaulescens (A. Gray) A. Nelson
- Trifolium Hansenii Greene
- Trifolium Haydenii Porter var. barnebyi Isely
- Trifolium Haydenii Porter var. haydenii
- Trifolium Helleri Kennedy
- Trifolium Heterodon Torr. & A. Gray
- Trifolium Howellii S. Watson var. latifolium (Hook.) McDermott
- Trifolium Hybridum L. ssp. elegans (Savi) Asch. & Graebn.
- Trifolium Hybridum L. var. elegans (Savi) Boiss.
- Trifolium Hybridum L. var. pratense Rabenh.
- Trifolium Hydrophilum Greene
- Trifolium Inaequale Rydb.
- Trifolium Incarnatum L. var. elatius Gibelli & Belli
- Trifolium Involucratum Ortega var. arizonicum (Greene) McDermott
- Trifolium Involucratum Ortega var. fendleri (Greene) McDermott
- Trifolium Involucratum Ortega var. fimbriatum (Lindl.) McDermott
- Trifolium Involucratum Ortega var. heterodon (Torr. & A. Gray) S. Watson
- Trifolium Involucratum Ortega var. kennedianum McDermott
- Trifolium Isodon Murb.
- Trifolium Isthmocarpum Brot.
- Trifolium Kennedianum (McDermott) A. Nelson & J.F. Macbr.
- Trifolium Kingii S. Watson ssp. dedeckerae (J.M. Gillett) D. Heller
- Trifolium Kingii S. Watson ssp. productum (Greene) D. Heller
- Trifolium Kingii S. Watson ssp. rollinsii (J.M. Gillett) D. Heller
- Trifolium Kingii S. Watson var. brandegeei (S. Watson) McDermott
- Trifolium Kingii S. Watson var. macilentum (Greene) Isely
- Trifolium Kingii S. Watson var. productum (Greene) Jeps.
- Trifolium Lacerum Greene
- Trifolium Lagopus Pourr. ex Willd.
- Trifolium Leucanthum M. Bieb.
- Trifolium Lilacinum Rydb., non Greene
- Trifolium Lividum Rydb.
- Trifolium Longicaule Wooton & Standl.
- Trifolium Longipes Nutt. var. atrorubens (Greene) Jeps.
- Trifolium Longipes Nutt. var. brachypus S. Watson
- Trifolium Longipes Nutt. var. elmeri (Greene) McDermott
- Trifolium Longipes Nutt. var. hansenii (Greene) Jeps.
- Trifolium Longipes Nutt. var. latifolium Hook.
- Trifolium Longipes Nutt. var. multiovulatum (L.F. Hend.) C.L. Hitchc.
- Trifolium Longipes Nutt. var. multipedunculatum (Kennedy) J.S. Martin ex Isely
- Trifolium Longipes Nutt. var. neurophyllum (Greene) J.S. Martin ex Isely
- Trifolium Longipes Nutt. var. nevadense Jeps.
- Trifolium Longipes Nutt. var. oreganum (Howell) Isely
- Trifolium Longipes Nutt. var. pedunculatum (Rydb.) C.L. Hitchc.
- Trifolium Longipes Nutt. var. pedunculatum (Rydb.) Isely
- Trifolium Longipes Nutt. var. pygmaeum A. Gray
- Trifolium Longipes Nutt. var. reflexum A. Nelson
- Trifolium Longipes Nutt. var. rusbyi (Greene) Harrington
- Trifolium Longipes Nutt. var. shastense (House) Jeps.
- Trifolium Lucanicum Gasp. ex Guss.
- Trifolium Macilentum Greene
- Trifolium Macilentum Greene var. dedeckerae (J.M. Gillett) Barneby
- Trifolium Macilentum Greene var. rollinsii (J.M. Gillett) Barneby
- Trifolium Macraei Hook. & Arn. var. albopurpureum (Torr. & A. Gray) Greene
- Trifolium Macraei Hook. & Arn. var. dichotomum (Hook. & Arn.) W.H. Brewer ex S. Wa
- Trifolium Macrocephalum (Pursh) Poir. var. caeruleomontanum H. St. John
- Trifolium Maritimum Huds.
- Trifolium Maritinum Huds., database artifact
- Trifolium Medium L. var. sarosiense (Hazsl.) Savul. & Rayss
- Trifolium Megalanthum Steud.
- Trifolium Melananthum Hook. & Arn.
- Trifolium Meneghinianum Clementi
- Trifolium Mercedense Kennedy
- Trifolium Michelianum Savi var. balansae (Boiss.) Andrz.
- Trifolium Microdon Hook. & Arn. var. pilosum Eastw.
- Trifolium Monanthum A. Gray ssp. vaughanae J.M. Gillett [excluded]
- Trifolium Monanthum A. Gray var. caulescens Loja.
- Trifolium Monanthum A. Gray var. eastwoodianum J.S. Martin
- Trifolium Monanthum A. Gray var. grantianum (A. Heller) Parish
- Trifolium Monanthum A. Gray var. monanthum
- Trifolium Monanthum A. Gray var. parvum (Kellogg) McDermott
- Trifolium Monanthum A. Gray var. pusillum (Greene) Jeps.
- Trifolium Monanthum A. Gray var. tenerum (Eastw.) Parish
- Trifolium Monoense Greene
- Trifolium Montanense Rydb.
- Trifolium Mucronatum Willd. ex Spreng. var. arizonicum (Greene) Isely
- Trifolium Multicaule M.E. Jones
- Trifolium Multipedunculatum Kennedy
- Trifolium Mutabile Port.
- Trifolium Nemorale Greene
- Trifolium Neolagopus Loja.
- Trifolium Nigrescens Viv. ssp. petrisavii (Clementi) Holmboe
- Trifolium Obscurum Savi
- Trifolium Obscurum Savi ssp. aequidentatum (Perez Lara) C. Vicioso
- Trifolium Occidentale Coombe
- Trifolium Olivaceum Greene var. columbianum (Greene) Jeps.
- Trifolium Olivaceum Greene var. griseum Jeps.
- Trifolium Orbiculatum Kennedy & McDermott
- Trifolium Oreganum Howell
- Trifolium Oreganum Howell var. multiovulatum L.F. Hend.
- Trifolium Oreganum Howell var. rydbergii (Greene) McDermott
- Trifolium Oxydon Greene ex Rydb.
- Trifolium Pallescens Schreb.
- Trifolium Pallidum Waldst. & Kit.
- Trifolium Palmeri S. Watson
- Trifolium Pannonicum Jacq. ssp. elongatum (Willd.) Zohary
- Trifolium Parryi A. Gray var. montanense (Rydb.) Isely
- Trifolium Parryi A. Gray var. montanense (Rydb.) S.L. Welsh
- Trifolium Parviflorum Ehrh.
- Trifolium Patens Schreb.
- Trifolium Pauciflorum Nutt.
- Trifolium Pauciflorum Nutt. var. parvum Kellogg
- Trifolium Pedunculatum Rydb.
- Trifolium Petraeum Greene
- Trifolium Petrophilum Greene ex A. Heller
- Trifolium Physodes Steven ex M. Bieb.
- Trifolium Pilulare Boiss.
- Trifolium Plummerae S. Watson
- Trifolium Plumosum Douglas ex Hook. var. amplifolium J.S. Martin
- Trifolium Polyodon Greene
- Trifolium Polystachyum Fresen.
- Trifolium Pratense L. var. frigidum auct. non Gaudin
- Trifolium Pratense L. var. sativum (Mill.) Schreb.
- Trifolium Procumbens L., nom. utique rej.
- Trifolium Purseglovei J.B. Gillett
- Trifolium Pusillum Greene
- Trifolium Reflexum L. var. glabrum Loja.
- Trifolium Reflexum L. var. virginicum (Small ex Small & Vail) McDermott
- Trifolium Repens L. var. atropurpureum hort.
- Trifolium Repens L. var. biasolettii (Steud. & Hochst.) Asch. & Graebn.
- Trifolium Repens L. var. giganteum Lagr.-Foss. [excluded]
- Trifolium Resupinatum L. var. majus Boiss.
- Trifolium Resupinatum L. var. suaveolens (Willd.) Dinsm.
- Trifolium Rubens L.
- Trifolium Rusbyi Greene
- Trifolium Rusbyi Greene ssp. caurinum (Piper) D. Heller & Zohary
- Trifolium Rusbyi Greene ssp. multipedunculatum (Kennedy) D. Heller & Zohary
- Trifolium Rusbyi Greene ssp. neurophyllum (Greene) D. Heller & Zohary
- Trifolium Rusbyi Greene ssp. oreganum (Howell) D. Heller & Zohary
- Trifolium Rusbyi Greene ssp. reflexum (A. Nelson) D. Heller & Zohary
- Trifolium Rusbyi Greene ssp. shastense (House) D. Heller & Zohary
- Trifolium Rusbyi Greene var. atrorubens Greene
- Trifolium Rydbergii Greene
- Trifolium Salictorum Greene ex Rydb.
- Trifolium Saxicola Small
- Trifolium Scariosum A. Nelson
- Trifolium Shastense House
- Trifolium Simulans House
- Trifolium Smyrnaeum Boiss.
- Trifolium Speciosum Willd.
- Trifolium Spinulosum Douglas ex Hook.
- Trifolium Squarrosum L.
- Trifolium Stenolobum Rydb.
- Trifolium Stenophyllum Nutt.
- Trifolium Strictum L.
- Trifolium Subcaulescens A. Gray
- Trifolium Supinum Savi
- Trifolium Sylvaticum Gérard ex Loisel.
- Trifolium Tenerum Eastw.
- Trifolium Thalii Vill.
- Trifolium Tomentosum L. var. curvisepalum (Tackh.) Thiebaut
- Trifolium Tomentosum L. var. tomentosum
- Trifolium Traskiae Kennedy
- Trifolium Trichocephalum M. Bieb.
- Trifolium Tridentatum Lindl.
- Trifolium Tridentatum Lindl. var. aciculare (Nutt.) McDermott
- Trifolium Tridentatum Lindl. var. obtusiflorum (Hook. f.) S. Watson
- Trifolium Trilobatum Jeps.
- Trifolium Truncatum (Greene) Greene
- Trifolium Tumens Steven ex M. Bieb.
- Trifolium Uintense Rydb.
- Trifolium Usambarense Taub.
- Trifolium Variegatum Nutt. var. geminiflorum (Greene) Vincent
- Trifolium Variegatum Nutt. var. major Loja.
- Trifolium Variegatum Nutt. var. melananthum (Hook. & Arn.) Greene
- Trifolium Variegatum Nutt. var. pauciflorum (Nutt.) McDermott
- Trifolium Variegatum Nutt. var. rostratum (Greene) C.L. Hitchc.
- Trifolium Variegatum Nutt. var. trilobatum (Jeps.) McDermott
- Trifolium Vernum Phil.
- Trifolium Villiferum House
- Trifolium Willdenovii Spreng. var. fimbriatum (Lindl.) Ewan
- Trifolium Willdenovii Spreng. var. kennedianum (McDermott) Ewan
- Trifolium Willdenovii Spreng. var. longicaule (Wooton & Standl.) L.D. Benson
- Trifolium Willdenowii Spreng., orth. var.
- Trifolium Wormskioldii Lehm. var. arizonicum (Greene) Barneby
- Trifolium Wormskioldii Lehm. var. fimbriatum (Lindl.) Jeps.
- Trifolium Wormskioldii Lehm. var. kennedianum (McDermott) Jeps.
- Trifolium Wormskioldii Lehm. var. longicaule (Wooton & Standl.) L.D. Benson
- Trifolium Wormskioldii Lehm. var. siskiyouense (J.M. Gillett) Isely
- Trifurcia Caerulea Herb.
- Trifurcia Lahue (Molina) Goldblatt ssp. caerulea (Herb.) Goldblatt
- Triglochin Concinna Burtt Davy var. concinna
- Triglochin Concinna Burtt Davy var. debilis (M.E. Jones) J.T. Howell, orth. var.
- Triglochin Concinnum Burtt Davy var. debile (M.E. Jones) J.T. Howell, orth. var.
- Triglochin Concinnum Burtt Davy, orth. var.
- Triglochin Debile (M.E. Jones) Á. Löve & D. Löve
- Triglochin Debilis (M.E. Jones) Á. Löve & D. Löve, orth. var.
- Triglochin Elata Nutt.
- Triglochin Elatum Nutt., orth. var.
- Triglochin Gaspense Lieth & D. Löve, orth. var.
- Triglochin Maritima L. var. elata (Nutt.) A. Gray
- Triglochin Maritimum L. var. elatum (Nutt.) A. Gray, orth. var.
- Triglochin Maritimum L., orth. var.
- Triglochin Palustre L., orth. var.
- Triglochin Scilloides (Poir.) Mering & Kadereit
- Triglochin Striatum Ruiz & Pav., orth. var.
- Trigonella Arabica Delile
- Trigonella Brachycarpa (Fisch. ex M. Bieb.) Moris
- Trigonella Cretica (L.) Boiss.
- Trigonella Gladiata Steven ex M. Bieb.
- Trigonella Laciniata auct. non L.
- Trigonella Monspeliaca L.
- Trigonella Neoana Boiss.
- Trigonella Ornithopodioides (L.) DC.
- Trigonella Polycarpa Boiss. & Heldr.
- Trigonella Polyceratia L.
- Trigonella Popovii Korovin
- Trigonella Ruthenica L.
- Trilisa Odoratissima (J.F. Gmel.) Cass.
- Trilisa Paniculata (J.F. Gmel.) Cass.
- Trillium Cernuum L. var. macranthum Eames & Wiegand
- Trillium Chloropetalum (Torr.) Howell var. angustipetalum (Torr.) Munz
- Trillium Cuneatum Raf. var. luteum (Muhl.) H.E. Ahles
- Trillium Declinatum auct. non (A. Gray) Gleason
- Trillium Erectum L. var. album Pursh
- Trillium Erectum L. var. blandum Jennison
- Trillium Erectum L. var. declinatum auct. non A. Gray
- Trillium Erectum L. var. flavum Torr.
- Trillium Erectum L. var. sulcatum Barksd.
- Trillium Erectum L. var. vaseyi (Harbison) H.E. Ahles
- Trillium Giganteum (Hook. & Arn.) A. Heller
- Trillium Gleasonii auct. non Fernald
- Trillium Hugeri Small
- Trillium Lanceolatum (S. Watson) Boykin ex Small
- Trillium Oostingii Gaddy
- Trillium Ovatum Pursh var. oettingeri (Munz & Thorne) Case
- Trillium Ozarkanum Palmer & Steyerm.
- Trillium Parviflorum Soukup
- Trillium Pusillum Michx. var. monticulum Bodkin & Reveal
- Trillium Pusillum Michx. var. texanum (Buckley) C.F. Reed
- Trillium Pusillum Michx. var. texanum (Buckley) Reveal & Broome
- Trillium Recurvatum Beck ssp. lanceolatum (S. Watson) A.E. Murray
- Trillium Sessile L. ssp. giganteum (Hook. & Arn.) A.E. Murray
- Trillium Sessile L. var. angustipetalum Torr.
- Trillium Sessile L. var. chloropetalum Torr.
- Trillium Sessile L. var. giganteum Hook. & Arn.
- Trillium Tennesseense E.E. Schill. & Floden
- Trillium - Trillium L.
- Trillium Virginianum (Fernald) C.F. Reed
- Trillium Viride Beck var. luteum (Muhl.) Gleason
- Trimezia Martinicensis auct. non (Jacq.) Herb.
- Trimezia - Trimezia Salisb. ex Herb.
- Trimmatothele Lichen - Trimmatothele Norman ex Zahlbr.
- Trimmatothele Lichen - Trimmatothele Umbellulariae Herre
- Trimorpha Acris (L.) Gray var. asteroides (Andrz. ex Besser) G.L. Nesom
- Trimorpha Acris (L.) Gray var. debilis (A. Gray) G.L. Nesom
- Trimorpha Acris (L.) Gray var. kamtschatica (DC.) G.L. Nesom
- Trimorpha Acris auct. non (L.) Gray p.p.
- Trimorpha Borealis Vierh.
- Trimorpha Elata (Hook.) G.L. Nesom
- Trimorpha Elongata (Ledeb.) Vierh.
- Trimorpha Lonchophylla (Hook.) G.L. Nesom
- Trimorpha Scotteri (B. Boivin) G.L. Nesom
- Trinidad Milkvetch - Astragalus Puniceus Osterh.
- Trinidad Milkvetch - Astragalus Puniceus Osterh. var. gertrudis (Greene) Barneby
- Trinidad Milkvetch - Astragalus Puniceus Osterh. var. puniceus
- Trinity Buckwheat - Eriogonum Alpinum Engelm.
- Trinity Mountain Rockcress - Arabis Rigidissima Rollins
- Trinity Mountain Rockcress - Arabis Rigidissima Rollins var. demota Rollins
- Trinity Mountain Rockcress - Arabis Rigidissima Rollins var. rigidissima
- Trinity Penstemon - Penstemon Tracyi D.D. Keck
- Trinity River Jewelflower - Streptanthus Oblanceolatus T.W. Nelson & J.P. Nelson
- Trinity Sphagnum - Sphagnum Trinitense Müll. Hal.
- Triodanis Perfoliata (L.) Nieuwl. var. biflora (Ruiz & Pav.) Bradley
- Triodanis Perfoliata (L.) Nieuwl. var. perfoliata
- Triodia Chapmanii (Small) Bush
- Triodia Drummondii Scribn. & Kearney
- Triodia Elliottii Bush
- Triodia Elongata (Buckley) Scribn.
- Triodia Eragrostoides Vasey & Scribn.
- Triodia Flava (L.) Smyth
- Triodia Mutica (Torr.) Scribn.
- Triodia Pulchella Kunth
- Triodia R. Br.
- Triodia Stricta (Nutt.) Benth. ex Vasey
- Trionum Trionum (L.) Wooton & Standl., nom. inval.
- Triorchos Ecristata (Fernald) Small
- Triosteum Angustifolium L. var. eamesii Wiegand
- Triosteum Illinoense (Wiegand) Rydb.
- Triosteum Perfoliatum L. var. aurantiacum (E.P. Bicknell) Wiegand
- Triosteum Perfoliatum L. var. glaucescens (Wiegand) Wiegand
- Triosteum Perfoliatum L. var. illinoense Wiegand
- Triphasia Glauca Lindl.
- Triphasia Trifoliata (L.) DC.
- Triphasia - Triphasia Lour.
- Triphora Cubensis (Rchb. f.) Ames
- Triphora Latifolia Luer f.
- Triphora Trianthophora (Sw.) Rydb. var. schaffneri Camp
- Triphora Trianthophoros (Sw.) Rydb., orth. var.
- Triphora Yucatanensis auct. non Ames
- Tripidium Ravennae (L.) H. Scholz
- Triplasis Intermedia Nash
- Tripleleaf Morning-glory - Ipomoea Ternifolia Cav.
- Tripleleaf Morning-glory - Ipomoea Ternifolia Cav. var. leptotoma (Torr.) J.A. McDonald
- Triplerib Milkvetch - Astragalus Tricarinatus A. Gray
- Tripleurospermum Inodorum (L.) Sch. Bip.
- Tripleurospermum Phaeocephalum (Rupr.) Pobed.
- Triploid Fern - Microsorum Spectrum (Kaulf.) Copeland
- Triplophyllum - Triplophyllum Holttum
- Tripod Buckwheat - Eriogonum Tripodum Greene
- Tripodion Medik.
- Tripodion Tetraphyllum (L.) Fourr.
- Tripogandra Elongata (G. Mey.) Woodson
- Tripogandra - Tripogandra Raf.
- Tripolium Angustum Lindl.
- Tripolium Frondosum Nutt.
- Tripolium Occidentale Nutt.
- Tripolium Oregonum Nutt.
- Tripolium Subulatum (L.) Nees var. parviflorum Nees
- Tripsacum Australe H.C. Cutler & E.S. Anderson
- Tripsacum Dactyloides (L.) L. var. occidentale Cutler & Anders.
- Tripsacum Hermaphrodita L.
- Tripsacum Laxum Nash
- Tripterocalyx Carnea (Greene) L.A. Galloway var. carnea (Greene) L.A. Galloway, orth.
- Tripterocalyx Carnea (Greene) L.A. Galloway var. wootonii (Standl.) L.A. Galloway, or
- Tripterocalyx Carnea (Greene) L.A. Galloway, orth. var.
- Tripterocalyx Cyclopterus (A. Gray) Standl.
- Tripterocalyx Pedunculatus (M.E. Jones) Standl.
- Tripterocalyx Wootonii Standl.
- Tripterocladium Moss - Tripterocladium (müll. Hal.) A. Jaeger
- Tripterocladium Moss - Tripterocladium Leucocladulum (Müll. Hal.) A. Jaeger
- Tripterocladium Rupestris (Kindb.) Kindb.
- Triquetrella Moss - Triquetrella Müll. Hal.
- Trisetobromus Hirtus (Trin.) Nevski
- Trisetum Brandegei Scribn.
- Trisetum Cernuum Trin.
- Trisetum Cernuum Trin. ssp. canescens (Buckley) Calder & Roy L. Taylor
- Trisetum Cernuum Trin. var. canescens (Buckley) Beal
- Trisetum Cernuum Trin. var. projectum (Louis-Marie) Beetle
- Trisetum Distichophyllum (Vill.) P. Beauv.
- Trisetum Latifolium Hitchc. [excluded]
- Trisetum Litorale (Rupr. ex Rosh.) Czern.
- Trisetum Melicoides (Michx.) Vasey ex Scribn. var. majus (A. Gray) Hitchc.
- Trisetum Molle Kunth
- Trisetum Montanum Vasey
- Trisetum Montanum Vasey var. shearii Louis-Marie
- Trisetum Pensylvanicum (L.) P. Beauv. ex Roem. & Schult.
- Trisetum Purpurascens Torr.
- Trisetum Spicatum (L.) K. Richt. ssp. alaskanum (Nash) Hultén
- Trisetum Spicatum (L.) K. Richt. ssp. congdonii (Scribn. & Merr.) Hultén
- Trisetum Spicatum (L.) K. Richt. ssp. majus (Rydb.) Hultén
- Trisetum Spicatum (L.) K. Richt. ssp. molle (Kunth) Hultén
- Trisetum Spicatum (L.) K. Richt. ssp. montanum (Vasey) W. Weber
- Trisetum Spicatum (L.) K. Richt. ssp. pilosiglume (Fernald) Hultén
- Trisetum Spicatum (L.) K. Richt. var. alaskanum (Nash) Malte ex Louis-Marie
- Trisetum Spicatum (L.) K. Richt. var. congdonii (Scribn. & Merr.) Hitchc.
- Trisetum Spicatum (L.) K. Richt. var. maidenii (Gandog.) Fernald
- Trisetum Spicatum (L.) K. Richt. var. majus (Rydb.) Farw.
- Trisetum Spicatum (L.) K. Richt. var. molle (Kunth) Beal
- Trisetum Spicatum (L.) K. Richt. var. pilosiglume Fernald
- Trisetum Spicatum (L.) K. Richt. var. projectum (Louis-Marie) J.T. Howell
- Trisetum Spicatum (L.) K. Richt. var. spicatiforme Hultén
- Trisetum Spicatum (L.) K. Richt. var. villosissimum (Lange) Louis-Marie
- Trisetum Subspicatum (L.) P. Beauv.
- Trisetum Triflorum (Bigelow) Á. Löve & D. Löve
- Trisetum Triflorum (Bigelow) Á. Löve & D. Löve ssp. molle (Kunth) Á. Löve & D. Löve
- Trisetum Villosissimum (Lange) Louis-Marie
- Trismeria Trifoliata (L.) Diels
- Tristania Conferta R. Br.
- Tristaniopsis - Tristaniopsis Brongn. & Gris
- Tristellateia Australasiae Rich.
- Tristellateia Thouars
- Tristiropsis Obtusangula Radlk.
- Tristiropsis Radlk.
- Triteleia Angustiflora A. Heller
- Triteleia Bicolor (Suksd.) Abrams
- Triteleia Gracilis (S. Watson) Greene
- Triteleia Howellii (S. Watson) Greene
- Triteleia Hyacinthina (Lindl.) Greene var. greenei Hoover
- Triteleia Ixioides (W.T. Aiton) Greene var. anilina (Greene) Hoover
- Triteleia Ixioides (W.T. Aiton) Greene var. cookii Hoover
- Triteleia Modesta (H.M. Hall) Abrams
- Triteleia Scabra (Greene) Greene ex Rattan
- Triteleia - Triteleia Douglas ex Lindl.
- Triteleia Uniflora Lindl.
- Triticale - Triticosecale Rimpaui C. Yen & J.L. Yang
- Triticale - ×triticosecale Wittm. ex A. Camus
- Triticosecale Rimpaui Wittm., nom. inval.
- Triticum Aegilopoides (Link) Bal. ex Koern.
- Triticum Aestivum L. var. spelta (L.) L.H. Bailey
- Triticum Boreale Turcz.
- Triticum Caninum L.
- Triticum Cereale (L.) Salisb.
- Triticum Compactum Host [excluded]
- Triticum Cylindricum (Host) Ces., Pass. & Gibelli
- Triticum Dicoccoides Koern. ex Schweinf.
- Triticum Dicoccon (Schrank) Schübl.
- Triticum Dicoccum (Schrank) Schübl., orth. var.
- Triticum Farctum Viv. p.p.
- Triticum Hybernum L.
- Triticum Junceum L. p.p.
- Triticum Macha Dekap. & Menab.
- Triticum Macrourum Turcz.
- Triticum Monococcum L. [excluded]
- Triticum Orientale Percival
- Triticum Ovatum (L.) Gren. & Godr. p.p.
- Triticum Palaeocolchicum Menabde
- Triticum Persicum (Boiss.) Aitch. & Hemsl.
- Triticum Persicum Vav. ex Zhuk.
- Triticum Polonicum L. [excluded]
- Triticum Pungens auct. non Pers.
- Triticum Pyramidale Percival
- Triticum Repens L.
- Triticum Sativum Lam.
- Triticum Spelta L. var. dicoccon Schrank, nom. inval.
- Triticum Sphaerococcum Percival
- Triticum Thaoudar Reuter ex Hausskn.
- Triticum Trachycaulum Link
- Triticum Triunciale (L.) Raspail
- Triticum Vaillantianum Wulfen & Schreb.
- Triticum Vulgare Vill.
- Tritomaria Exsecta (Schrad.) Loeske
- Tritomaria Exsectiformis (Breidl.) Loeske
- Tritomaria Exsectiformis (Breidl.) Loeske ssp. arctica R.M. Schust.
- Tritomaria Exsectiformis (Breidl.) Loeske ssp. exsectiformis
- Tritomaria Heterophylla R.M. Schust.
- Tritomaria Polita (Nees) Jörg.
- Tritomaria Polita (Nees) Jörg. ssp. polita
- Tritomaria Polita (Nees) Jörg. ssp. polymorpha R.M. Schust.
- Tritomaria Quinquedentata (Huds.) H. Buch
- Tritomaria Quinquedentata (Huds.) H. Buch ssp. quinquedentata
- Tritomaria Quinquedentata (Huds.) H. Buch ssp. quinquedentata var. grandiretis H. Buch & S
- Tritomaria Quinquedentata (Huds.) H. Buch ssp. quinquedentata var. quinquedentata
- Tritomaria Quinquedentata (Huds.) H. Buch ssp. turgida (Lindb.) Damsh.
- Tritomaria Schiffn. ex Loeske
- Tritomaria Scitula (Taylor) Jörg.
- Tritonia ×crocosmiiflora (V. Lemoine) G. Nicholson
- Triumfetta Bartramia L.
- Triumfetta Excisa Urb.
- Triumfetta Procumbens G. Forst.
- Triumfetta Velutina Vahl [excluded]
- Trivial Absconditella Lichen - Absconditella Trivialis (Willey ex Tuck.) Vezda
- Trixis Californica Kellogg var. californica
- Trixis Radialis (L.) Kuntze
- Trojan Beet - Beta Trojana A. Pamukc. ex Aellen
- Trollius Albiflorus (A. Gray) Rydb.
- Trollius Laxus Salisb. var. albiflorus A. Gray
- Trommsdorffia Argentea Mart.
- Tronchuda Cabbage - Brassica Oleracea L. var. costata DC.
- Trophis - Trophis P. Br.
- Tropic Daisy - Egletes Cass.
- Tropic Shield Lichen - Heterodermia Tropica (Kurok.) Sipman
- Tropic Trypelthelium Lichen - Trypethelium Tropicum (Ach.) Müll. Arg.
- Tropical Adderstongue - Ophioglossum Concinnum Brack.
- Tropical Almond - Terminalia Catappa L.
- Tropical Almond - Terminalia L.
- Tropical Amaranth - Amaranthus Polygonoides L.
- Tropical Beaksedge - Rhynchospora Contracta (Nees) J. Raynal
- Tropical Bent - Bromidium Nees & Meyen
- Tropical Blazingstar - Mentzelia Aspera L.
- Tropical Bloodleaf - Iresine Argentata (Mart.) D. Dietr.
- Tropical Bog Orchid - Habenaria Monorrhiza (Sw.) Rchb. f.
- Tropical Brackenfern - Pteridium Arachnoideum (Kaulf.) Maxon
- Tropical Bristlegrass - Setaria Tenacissima Schrad.
- Tropical Burnweed - Erechtites Valerianifolius (Link ex Spreng.) DC.
- Tropical Bushmint - Hyptis Mutabilis (A. Rich.) Briq.
- Tropical Buttonweed - Diodia Sarmentosa Sw.
- Tropical Chinchweed - Pectis Elongata Kunth
- Tropical Chinchweed - Pectis Elongata Kunth var. floribunda (A. Rich.) Keil
- Tropical Cowpea - Vigna Juruana (Harms) Verdc.
- Tropical Crabgrass - Digitaria Argillacea (Hitchc. & Chase) Fernald
- Tropical Creeping Cudweed - Euchiton Sphaericus (Willd.) Anderb.
- Tropical Cupgrass - Eriochloa Fatmensis (Hochst. & Steud.) W.D. Clayton
- Tropical Dancing-lady Orchid - Tolumnia Prionochila (Kraenzlin) G.J. Braem
- Tropical Desert-thorn - Lycium Tweedianum Griseb.
- Tropical Desert-thorn - Lycium Tweedianum Griseb. var. chrysocarpum (Urb. & Ekman) C.L. Hitchc.
- Tropical Desert-thorn - Lycium Tweedianum Griseb. var. tweedianum Griseb. [excluded]
- Tropical Dock - Rumex Obovatus Danser
- Tropical Dropseed - Sporobolus Tenuissimus (Mart. ex Schrank) Kuntze
- Tropical False Goldeneye - Heliomeris Soliceps (Barneby) Yates
- Tropical Fanleaf - Fioria Vitifolia (L.) Mattei
- Tropical Fanpetals - Sida Urens L.
- Tropical Fimbry - Fimbristylis Cymosa R. Br. ssp. cymosa
- Tropical Fimbry - Fimbristylis Cymosa R. Br. ssp. umbellatacapitata (Hillebr.) T. Koyama
- Tropical Flatsedge - Cyperus Surinamensis Rottb.
- Tropical Forkedfern - Dicranopteris Rubiginosa (Mett.) Maxon
- Tropical Girdlepod - Mitracarpus Hirtus (L.) DC.
- Tropical Govenia - Govenia Floridana P.M. Brown
- Tropical Hayscented Fern - Dennstaedtia Cicutaria (Sw.) T. Moore
- Tropical Kudzu - Pueraria Phaseoloides (Roxb.) Benth.
- Tropical Ladies'-tresses - Hapalorchis Lineatus (Lindl.) Schltr.
- Tropical Leaf-flower - Phyllanthus Pulcher Wall. ex Müll. Arg.
- Tropical Leafbract - Malachra Radiata L.
- Tropical Lilythorn - Catesbaea Melanocarpa Krug & Urb.
- Tropical Marshpennywort - Hydrocotyle Pusilla A. Rich.
- Tropical Medicineplant - Adenostemma Verbesina (L.) Sch. Bip.
- Tropical Mexican Clover - Richardia Brasiliensis Gomes
- Tropical Milkwort - Polygala Glochidiata Kunth
- Tropical Mistletoe - Phoradendron Hexastichum (DC.) Griseb.
- Tropical Needlegrass - Nassella Manicata (Desv.) Barkworth
- Tropical Nutrush - Scleria Microcarpa Nees ex Kunth
- Tropical Panicgrass - Panicum Trichoides Sw.
- Tropical Paspalum - Paspalum Pleostachyum Döll
- Tropical Passionflower - Passiflora Anadenia Urb.
- Tropical Pickerelweed - Pontederia Rotundifolia L. f.
- Tropical Pokeweed - Phytolacca Icosandra L.
- Tropical Pondweed - Potamogeton Insulanus Hagstr.
- Tropical Puff - Neptunia Pubescens Benth.
- Tropical Puff - Neptunia Pubescens Benth. var. microcarpa (Rose) Windler
- Tropical Puff - Neptunia Pubescens Benth. var. pubescens
- Tropical Rose Mallow - Hibiscus Vitifolius L.
- Tropical Royalblue Waterlily - Nymphaea Elegans Hook.
- Tropical Sage - Salvia Misella Kunth
- Tropical Seapurslane - Sesuvium Crithmoides Welw.
- Tropical Sensitive Pea - Chamaecrista Absus (L.) Irwin & Barneby
- Tropical Sensitive Pea - Chamaecrista Absus (L.) Irwin & Barneby var. absus (L.) Irwin & Barneby [excluded]
- Tropical Sensitive Pea - Chamaecrista Absus (L.) Irwin & Barneby var. meonandra (Irwin & Barneby) Irwin & Ba
- Tropical Signalgrass - Urochloa Distachya (L.) T.Q. Nguyen
- Tropical Soda Apple - Solanum Viarum Dunal
- Tropical Spiderflower - Cleome Stenophylla Klotzsch ex Urb.
- Tropical Sundew - Drosera Burmannii Vahl
- Tropical Thoroughwort - Fleischmannia Microstemon (Cass.) R.M. King & H. Rob.
- Tropical Threefold - Trixis Inula Crantz
- Tropical Ticktrefoil - Desmodium Cajanifolium (Kunth) DC.
- Tropical Tube Tongue - Siphonoglossa Sessilis (Jacq.) D. Gibson
- Tropical Twigrush - Machaerina Mariscoides (Gaudich.) J. Kern
- Tropical Twigrush - Machaerina Mariscoides (Gaudich.) J. Kern ssp. mariscoides (Gaudich.) J. Kern [excluded
- Tropical Waterclover - Marsilea Ancylopoda A. Braun
- Tropical Waterhyssop - Bacopa Innominata (G. Maza) Alain
- Tropical Waterwillow - Justicia Sphaerosperma Vahl.
- Tropical Waxweed - Cuphea Aspera Chapm.
- Tropical White Morning-glory - Ipomoea Alba L.
- Tropical Whitetop - Rhynchospora Radicans (Schltdl. & Cham.) H. Pfeifer
- Tropical Whitetop - Rhynchospora Radicans (Schltdl. & Cham.) H. Pfeifer ssp. microcephala (Bertero ex Spre
- Tropical Whiteweed - Ageratum Conyzoides L.
- Tropical Widelip Orchid - Liparis Vexillifera (Llave & Lex.) Cogn.
- Tropical Wild Petunia - Ruellia Brevifolia (Pohl) Ezcurra
- Tropical Woodsorrel - Oxalis Hirta L.
- Tropidia - Tropidia Lindl.
- Tropidocarpum Gracile Hook. var. dubium (Davidson) Jeps.
- Tropidocarpum - Tropidocarpum Hook.
- Trotter's Alpineparsley - Oreoxis Trotteri S.L. Welsh & Goodrich
- Troubled Milkvetch - Astragalus Anxius R.J. Meinke & Kaye
- Troublesome Sedge - Carex Molesta Mack. ex Bright
- Trout Creek Milkvetch - Astragalus Salmonis M.E. Jones
- Troximon Apargioides Less.
- Troximon Aurantiacum Hook.
- Troximon Glaucum Pursh
- Troximon Glaucum Pursh var. dasycephalum Torr. & A. Gray
- Troximon Grandiflorum Nutt.
- Troximon Parviflorum Nutt.
- Truckee Cryptantha - Cryptantha Glomeriflora Greene
- Truckee Lecidea Lichen - Lecidea Truckeei Herre
- Truckee Lewisia - Lewisia Longipetala (Piper) S. Clay
- Truckee Rabbitbrush - Chrysothamnus Humilis Greene
- True Babystars - Leptosiphon Bicolor Nutt.
- True Babystars - Leptosiphon Minimus (H. Mason) R. Battaglia
- True Forget-me-not - Myosotis Scorpioides L.
- True Indigo - Indigofera Tinctoria L.
- True's Manzanita - Arctostaphylos Mewukka Merriam ssp. truei (W. Knight) P.V. Wells
- Truellum Sagittatum (L.) Soják
- Trujillo Coca - Erythroxylum Novogranatense (Morris) Hieron. var. truxillense (Rusby) Plowman
- Trumpet - Collomia Nutt.
- Trumpet Creeper - Campsis Radicans (L.) Seem. ex Bureau
- Trumpet Evening Primrose - Oenothera Jamesii Torr. & A. Gray
- Trumpet Gooseberry - Ribes Leptanthum A. Gray
- Trumpet Honeysuckle - Lonicera Sempervirens L.
- Trumpet Tree - Cecropia Obtusifolia Bertol.
- Trumpet-tree - Tabebuia Gomes ex DC.
- Trumpetbush - Tecoma Juss.
- Trumpetflower - Gelsemium Juss.
- Trumpets - Acleisanthes A. Gray
- Trumpetweed - Eutrochium Fistulosum (Barratt) E.E. Lamont
- Truncate Pottia Moss - Pottia Truncata (Hedw.) Fürnr.
- Tryon's Woodsia - Woodsia ×tryonis B. Boivin
- Trypelthelium Lichen - Trypethelium Aeneum (Eschw.) Zahlbr.
- Trypelthelium Lichen - Trypethelium Eluteriae Spreng.
- Trypelthelium Lichen - Trypethelium Mastoideum (Ach.) Ach.
- Trypelthelium Lichen - Trypethelium Nitidiusculum (Nyl.) R.C. Harris
- Trypelthelium Lichen - Trypethelium Ochroleucum (Eschw.) Nyl.
- Trypelthelium Lichen - Trypethelium Spreng.
- Trypelthelium Lichen - Trypethelium Virens Tuck. ex Michener
- Trypethel's Buelliella Lichen - Buelliella Trypethelii (Tuck.) Fink
- Trypethelium Annulare (Fée) Mont.
- Trypethelium Carolinianum (Tuck.) R.C. Harris
- Trypethelium Catervarium (Fée) Tuck.
- Trypethelium Catervarium auct.
- Trypethelium Exocanthum Tuck.
- Trypethelium Pallescens Fée
- Trypethelium Scorites Tuck.
- Trypethelium Subeluteriae Makhija & Patwardhan
- Trypethelium Variolosum Ach.
- Tryphane Rubella (Wahlenb.) Rchb.
- Tschonosky Privet - Ligustrum Tschonoskii Decne.
- Tsuga Szczawinskia Lichen - Szczawinskia Tsugae Funk
- Tuart - Eucalyptus Gomphocephala DC.
- Tuba Milkweed - Asclepias Tomentosa Elliott
- Tubaroot - Paraderris Elliptica (Wall.) Adema
- Tubaroot - Paraderris Montana (Benth.) Adema
- Tube Lichen - Hypogymnia (nyl.) Nyl.
- Tube Lichen - Hypogymnia Austerodes (Nyl.) Rasanen
- Tube Lichen - Hypogymnia Enteromorpha (Ach.) Nyl.
- Tube Lichen - Hypogymnia Farinacea Zopf
- Tube Lichen - Hypogymnia Heterophylla L. Pike
- Tube Lichen - Hypogymnia Lugubris (Pers.) Krog
- Tube Lichen - Hypogymnia Metaphysodes (Asah.) Rass.
- Tube Lichen - Hypogymnia Mollis L. Pike & Hale
- Tube Lichen - Hypogymnia Physodes (L.) Nyl.
- Tube Lichen - Hypogymnia Pulverata (Nyl. ex Crombie) Elix
- Tube Lichen - Hypogymnia Rugosa (G. Merr.) L. Pike
- Tube Lichen - Hypogymnia Subcapitata (Nyl.) Rass.
- Tube Lichen - Hypogymnia Subobscura (Vain.) Poelt
- Tube Lichen - Hypogymnia Tubulosa (Schaerer) Hav.
- Tube Tongue - Siphonoglossa Oerst.
- Tubeflower Bluecup - Githopsis Tenella Morin
- Tuber Anemone - Anemone Tuberosa Rydb.
- Tuber Anemone - Anemone Tuberosa Rydb. var. texana Enquist & Crozier
- Tuber Anemone - Anemone Tuberosa Rydb. var. tuberosa
- Tuber Fleeceflower - Polygonum Multiflorum Thunb.
- Tuber Starwort - Pseudostellaria Jamesiana (Torr.) W.A. Weber & R.L. Hartm.
- Tuberaria Guttata (L.) Fourr.
- Tubercle Dodder - Cuscuta Tuberculata Brandegee
- Tubercle Dot Lichen - Micarea Tuberculata (Sommerf.) R. Anderson
- Tubercle Twistedstalk - Streptopus Amplexifolius (L.) DC. var. chalazatus Fassett
- Tubercled Horsfieldia - Horsfieldia Tuberculata (K. Schum.) Warb.
- Tubercled Horsfieldia - Horsfieldia Tuberculata (K. Schum.) Warb. var. tuberculata
- Tubercled Saltbush - Atriplex Acanthocarpa (Torr.) S. Watson
- Tubercled Saltbush - Atriplex Acanthocarpa (Torr.) S. Watson ssp. acanthocarpa
- Tubercled Saltbush - Atriplex Acanthocarpa (Torr.) S. Watson ssp. coahuilensis Henrickson
- Tuberose - Manfreda Salisb.
- Tuberose - Polianthes Tuberosa L.
- Tuberous Bulrush - Bolboschoenus Glaucus (Lam.) S.G. Sm.
- Tuberous Comfrey - Symphytum Tuberosum L.
- Tuberous Desert-chicory - Pyrrhopappus Grandiflorus (Nutt.) Nutt.
- Tuberous Grasspink - Calopogon Tuberosus (L.) Britton, Sterns & Poggenb.
- Tuberous Grasspink - Calopogon Tuberosus (L.) Britton, Sterns & Poggenb. var. tuberosus
- Tuberous Jerusalem Sage - Phlomis Tuberosa L.
- Tuberous Passionflower - Passiflora Tuberosa Jacq.
- Tuberous Springbeauty - Claytonia Tuberosa Pall. ex Schult.
- Tuberous Springbeauty - Claytonia Tuberosa Pall. ex Schult. var. czukczorum (Volkova) Hultén
- Tuberous Springbeauty - Claytonia Tuberosa Pall. ex Schult. var. tuberosa
- Tuberous Stoneseed - Lithospermum Tuberosum Rugel ex DC.
- Tuberous Sweetpea - Lathyrus Tuberosus L.
- Tuberous Vervain - Verbena Rigida Spreng.
- Tubiflora Acuminata Small
- Tubiflora Angustifolia (Fernald) Small
- Tubiflora Caroliniensis J.F. Gmel.
- Tubular Bluestar - Amsonia Longiflora Torr.
- Tubular Bluestar - Amsonia Longiflora Torr. var. longiflora
- Tubular Bluestar - Amsonia Longiflora Torr. var. salpignantha (Woodson) S.P. McLaughlin
- Tuckahoe Dewberry - Rubus Novocaesarius L.H. Bailey
- Tucker Oak - Quercus John-tuckeri Nixon & C.H. Mull.
- Tucker's Anisomeridium Lichen - Anisomeridium Tuckerae R.C. Harris
- Tuckerman's Dot Lichen - Arthonia Tuckermaniana Willey
- Tuckerman's Earth Lichen - Catapyrenium Tuckermanii (Rav. ex Mont.) J.W. Thomson
- Tuckerman's Fishscale Lichen - Psora Tuckermanii R. Anderson ex Timdal
- Tuckerman's Pondweed - Potamogeton Confervoides Rchb.
- Tuckerman's Quillwort - Isoetes Tuckermanii A. Braun
- Tuckerman's Ragged Lichen - Platismatia Tuckermanii (Oakes) W.L. Culb. & C.F. Culb.
- Tuckerman's Sedge - Carex Tuckermanii Dewey
- Tuckermannia Gigantea (Kellogg) M.E. Jones
- Tuckermannia Maritima Nutt.
- Tuckermannopsis Aurescens (Tuck.) Hale
- Tuckermannopsis Californica (Tuck.) ?, ined.?
- Tuckermannopsis Canadensis (Rasanen) Hale
- Tuckermannopsis Halei (W.L. Culb. & C.F. Culb.) M.J. Lai
- Tuckermannopsis Inermis (Nyl.) Karnefelt
- Tuckermannopsis Juniperina (L.) Hale
- Tuckermannopsis Lichen - Tuckermannopsis Ciliaris (Ach.) Gyel.
- Tuckermannopsis Lichen - Tuckermannopsis Coralligera (W.A. Weber) W.A. Weber
- Tuckermannopsis Lichen - Tuckermannopsis Gyel.
- Tuckermannopsis Lichen - Tuckermannopsis Orbata (Nyl.) M.J. Lai
- Tuckermannopsis Lichen - Tuckermannopsis Playtphylla (Tuck.) Hale
- Tuckermannopsis Lichen - Tuckermannopsis Sepincola (Ehrh.) Hale
- Tuckermannopsis Merrillii (Du Rietz) Hale
- Tuckermannopsis Oakesiana (Tuck.) Hale
- Tuckermannopsis Pallidula (Tuck. ex Riddle) Hale
- Tuckermannopsis Pinastri (Scop.) Hale
- Tuckermannopsis Subalpina (Imshaug) Karnefelt
- Tuckermannopsis Viridis (Schwein.) Hale
- Tuckermannopsis Weberi (Essl.) ?, ined.?
- Tucson Bur Ragweed - Ambrosia Cordifolia (A. Gray) Payne
- Tucson Cracked Lichen - Acarospora Tucsonensis H. Magn.
- Tucson Entosthodon Moss - Entosthodon Tucsonii (E.B. Bartram) Grout
- Tucson Mountain Spiderling - Boerhavia Megaptera Standl.
- Tucson Pricklypear - Cylindropuntia ×tetracantha (Toumey) F.M. Knuth (pro sp.)
- Tucson Xanthoparmelia Lichen - Xanthoparmelia Tucsonensis (T. Nash) Egan
- Tuerckheimia Moss - Tuerckheimia Angustifolia (K. Saito) R.H. Zander
- Tuerckheimia Moss - Tuerckheimia Broth.
- Tuffybells - Wahlenbergia Linarioides (Lam.) A. DC.
- Tufted Airplant - Guzmania Ruiz & Pav.
- Tufted Alpine Saxifrage - Saxifraga Caespitosa L.
- Tufted Alpine Saxifrage - Saxifraga Caespitosa L. ssp. caespitosa
- Tufted Alpine Saxifrage - Saxifraga Caespitosa L. ssp. delicatula (Small) A.E. Porsild
- Tufted Alpine Saxifrage - Saxifraga Caespitosa L. ssp. monticola (Small) A.E. Porsild
- Tufted Alpine Saxifrage - Saxifraga Caespitosa L. ssp. sileneflora (Sternb. ex Cham.) Hultén
- Tufted Alpine Saxifrage - Saxifraga Caespitosa L. ssp. subgemmifera Engl. & Irmsch.
- Tufted Alpine Saxifrage - Saxifraga Caespitosa L. ssp. uniflora (R. Br.) A.E. Porsild
- Tufted Alumroot - Heuchera Caespitosa Eastw.
- Tufted Bulrush - Trichophorum Cespitosum (L.) Hartm.
- Tufted Cryptantha - Cryptantha Caespitosa (A. Nelson) Payson
- Tufted Evening Primrose - Oenothera Caespitosa Nutt.
- Tufted Evening Primrose - Oenothera Caespitosa Nutt. ssp. caespitosa
- Tufted Evening Primrose - Oenothera Caespitosa Nutt. ssp. crinita (Rydb.) Munz
- Tufted Evening Primrose - Oenothera Caespitosa Nutt. ssp. macroglottis (Rydb.) W.L. Wagner
- Tufted Evening Primrose - Oenothera Caespitosa Nutt. ssp. marginata (Nutt. ex Hook. & Arn.) Munz
- Tufted Fescue - Festuca Airoides Lam. [excluded]
- Tufted Flax - Linum Imbricatum (Raf.) Shinners
- Tufted Fleabane - Erigeron Caespitosus Nutt.
- Tufted Frasera - Frasera Paniculata Torr.
- Tufted Globe Amaranth - Gomphrena Caespitosa Torr.
- Tufted Globemallow - Sphaeralcea Caespitosa M.E. Jones
- Tufted Globemallow - Sphaeralcea Caespitosa M.E. Jones var. caespitosa
- Tufted Hairgrass - Deschampsia Cespitosa (L.) P. Beauv.
- Tufted Hairsedge - Bulbostylis Vestita (Kunth) C.B. Clarke
- Tufted Lacefern - Aspidotis Carlotta-halliae (W.H. Wagner & E.F. Gilbert) Lellinger, (pro. hybr.)
- Tufted Lineleaf Fern - Antrophyum Intramarginale (Baker ex Jenman) Kartesz & Gandhi
- Tufted Loosestrife - Lysimachia Thyrsiflora L.
- Tufted Lovegrass - Eragrostis Pectinacea (Michx.) Nees ex Steud.
- Tufted Lovegrass - Eragrostis Pectinacea (Michx.) Nees ex Steud. var. pectinacea
- Tufted Milkvetch - Astragalus Spatulatus Sheldon
- Tufted Milkweed - Asclepias Nummularia Torr.
- Tufted Orchid - Jacquiniella Schltr.
- Tufted Pearlwort - Sagina Caespitosa (J. Vahl) Lange
- Tufted Penstemon - Penstemon Laxus A. Nelson
- Tufted Phlox - Phlox Caespitosa Nutt.
- Tufted Poppy - Eschscholzia Caespitosa Benth.
- Tufted Townsend Daisy - Townsendia Scapigera D.C. Eaton
- Tufted Twinpod - Physaria Condensata Rollins
- Tufted Wallaby Grass - Rytidosperma Caespitosum (Gaudich.) Connor & Edgar
- Tufted Wheatgrass - Elymus Macrourus (Turcz.) Tzvelev
- Tufted Wirelettuce - Stephanomeria Paniculata Nutt.
- Tufted Yellow Woodsorrel - Oxalis Priceae Small
- Tufted Yellow Woodsorrel - Oxalis Priceae Small ssp. colorea (Small) Eiten
- Tufted Yellow Woodsorrel - Oxalis Priceae Small ssp. priceae
- Tuftedstem Rush - Juncus Brachyphyllus Wiegand
- Tulare County Rockcress - Arabis Pygmaea Rollins
- Tulare Cryptantha - Cryptantha Incana Greene
- Tulare Gooseberry - Ribes Tularense (Coville) Fedde
- Tulare Saltbush - Atriplex Tularensis Coville
- Tule - Schoenoplectus Acutus (Muhl. ex Bigelow) Á. Löve & D. Löve var. occidentalis (S. Watso
- Tulip Poppy - Papaver Glaucum Boiss. & Hausskn.
- Tulip Pricklypear - Opuntia Camanchica Engelm. & J.M. Bigelow
- Tulip Pricklypear - Opuntia Laevis J.M. Coult.
- Tulip Pricklypear - Opuntia Phaeacantha Engelm.
- Tulip - Tulipa L.
- Tulip-wood Tree - Harpullia Arborea (Blanco) Radlk.
- Tulipa Batalinii Regel
- Tulipa Dasystemon (Regel) Regel
- Tulipa Greigii Regel
- Tulipa Praestans Hoog
- Tulipa Tarda Stapf
- Tulipa Turkestanica (Regel) Regel
- Tulipastrum Acuminatum (L.) Small
- Tulipastrum Cordatum (Michx.) Small
- Tuliptree - Liriodendron L.
- Tuliptree - Liriodendron Tulipifera L.
- Tum Bladderpod - Lesquerella Rubicundula Rollins
- Tumamoc Globeberry - Tumamoca Macdougalii Rose
- Tumamoca - Tumamoca Rose
- Tumble Lovegrass - Eragrostis Sessilispica Buckley
- Tumble Windmill Grass - Chloris Verticillata Nutt.
- Tumbledown Gum - Eucalyptus Dealbata A. Cunn. ex Schauer
- Tumblegrass - Schedonnardus Paniculatus (Nutt.) Trel.
- Tumblegrass - Schedonnardus Steud.
- Tumblemustard - Thelypodiopsis Rydb.
- Tumbling Saltweed - Atriplex Rosea L.
- Tumion Taxifolium (Arn.) Greene
- Tuna - Consolea Moniliformis (L.) Britton
- Tunbridge Filmy Fern - Hymenophyllum Tunbrigense (L.) Sm.
- Tundra Alkaligrass - Puccinellia Tenella (Lange) Holmb. ex A.E. Porsild
- Tundra Alkaligrass - Puccinellia Tenella (Lange) Holmb. ex A.E. Porsild ssp. alaskana (Scribn. & Merr.) T
- Tundra Alkaligrass - Puccinellia Tenella (Lange) Holmb. ex A.E. Porsild ssp. langeana (Berlin) Tzvelev
- Tundra Alkaligrass - Puccinellia Tenella (Lange) Holmb. ex A.E. Porsild ssp. tenella
- Tundra Aster - Oreostemma Alpigenum (Torr. & A. Gray) Greene
- Tundra Aster - Oreostemma Alpigenum (Torr. & A. Gray) Greene var. alpigenum
- Tundra Aster - Oreostemma Alpigenum (Torr. & A. Gray) Greene var. andersonii (A. Gray) G.L. Nesom
- Tundra Aster - Oreostemma Alpigenum (Torr. & A. Gray) Greene var. haydenii (Porter) G.L. Nesom
- Tundra Buttercup - Ranunculus Eximius Greene
- Tundra Chickweed - Cerastium Gorodkovianum Schischkin
- Tundra Fescue - Festuca Lenensis Drobow
- Tundra Fleabane - Erigeron Hyperboreus Greene
- Tundra Milkvetch - Astragalus Umbellatus Bunge
- Tundra Pohlia Moss - Pohlia Tundrae Shaw
- Tundra Sandwort - Arenaria Pseudofrigida (Ostenf. & O.C. Dahl) Juz. ex Schischk. & Knorring
- Tundra Shootingstar - Dodecatheon Austrofrigidum K.L. Chambers
- Tundra Warnstorfia Moss - Warnstorfia Tundrae (Arnell) Loeske
- Tundra Wildrye - Elymus Sajanensis (Nevski) Tzvelev
- Tundra Woodrush - Luzula Kjellmaniana Miyabe & Kudo
- Tundragrass - Dupontia R. Br.
- Tungoil Tree - Vernicia Fordii (Hemsl.) Airy-Shaw
- Tunica Prolifera (L.) Scop.
- Tunica Saxifraga (L.) Scop.
- Tunica Velutina (Guss.) Fisch. & C.A. Mey.
- Tunnel Springs Beardtongue - Penstemon Concinnus D.D. Keck
- Tunnel Springs Mountain Bladderpod - Lesquerella Goodrichii Rollins
- Tunp Range Twinpod - Physaria Dornii Lichvar
- Tununk Saltbush - Atriplex Minuticarpa Stutz & G.L. Chu
- Tuolumne Eryngo - Eryngium Pinnatisectum Jeps.
- Tuolumne Fawnlily - Erythronium Tuolumnense Applegate
- Tupa Portoricensis Vatke
- Tupa Robusta (Graham) A. DC.
- Tupelo - Nyssa L.
- Turban Prickly Pear - Opuntia Turbinata Small
- Turban Sedge - Carex Turbinata Liebm.
- Turbina - Turbina Raf.
- Turbinicarpus Gautii (L.D. Benson) A.D. Zimmerman
- Turgid Aulacomnium Moss - Aulacomnium Turgidum (Wahlenb.) Schwägr.
- Turgid Blazing Star - Liatris Turgida Gaiser
- Turgid Brachythecium Moss - Brachythecium Turgidum (Hartm.) Kindb.
- Turgid Cup Lichen - Cladonia Turgida Hoffm.
- Turgidosculum Complicatulum (Nyl.) Kohlm. & E. Kohlm.
- Turion Duckweed - Lemna Turionifera Landolt
- Turk's Cap - Melocactus Intortus (Mill.) Urb.
- Turk's Head - Ferocactus Hamatacanthus (Muehlenpf.) Britton & Rose
- Turk's Head - Ferocactus Hamatacanthus (Muehlenpf.) Britton & Rose var. hamatacanthus
- Turk's Head - Ferocactus Hamatacanthus (Muehlenpf.) Britton & Rose var. sinuatus (A. Dietr.) L.D. Benso
- Turk's Turbin - Clerodendrum Indicum (L.) Kuntze
- Turk's-cap Lily - Lilium Superbum L.
- Turkey Berry - Solanum Torvum Sw.
- Turkey Corn - Dicentra Eximia (Ker Gawl.) Torr.
- Turkey Oak - Quercus Laevis Walter
- Turkey Pea - Sanicula Tuberosa Torr.
- Turkey Tangle Fogfruit - Phyla Nodiflora (L.) Greene
- Turkeypeas - Astragalus Nuttallianus DC. var. cedrosensis M.E. Jones
- Turkeypeas - Astragalus Nuttallianus DC. var. imperfectus (Rydb.) Barneby
- Turkeypeas - Astragalus Nuttallianus DC. var. macilentus (Small) Barneby
- Turkeypeas - Astragalus Nuttallianus DC. var. micranthiformis Barneby
- Turkeypeas - Astragalus Nuttallianus DC. var. trichocarpus Torr. & A. Gray
- Turkeypeas - Astragalus Nuttallianus DC. var. zapatanus Barneby
- Turkish Baby's-breath - Gypsophila Pilosa Huds.
- Turkish Hawksbeard - Crepis Nicaeensis Balbis ex Pers.
- Turkish Hazelnut - Corylus Colurna L.
- Turkish Hazelnut - Corylus Colurna L. var. colurna
- Turkish Rugging - Chorizanthe Staticoides Benth.
- Turkish Wartycabbage - Bunias Orientalis L.
- Turner Wildrye - ×elyleymus Turneri (Lepage) Barkworth & D.R.Dewey
- Turner's Buttercup - Ranunculus Turneri Greene
- Turner's Crabseye Lichen - Ochrolechia Turneri (Sm.) Hasselrot
- Turner's Four-nerve Daisy - Tetraneuris Turneri (K.F. Parker) K.F. Parker
- Turner's Hawthorn - Crataegus Turnerorum Enquist
- Turner's Horseweed - Laennecia Turnerorum G.L. Nesom
- Turner's Water-willow - Justicia Turneri Hilsenb.
- Turnera Angustifolia Mill. [excluded]
- Turnera Aphrodisiaca G.H. Ward
- Turnera Cistoides L.
- Turnera Microphylla Desv.
- Turnera Ovata Bello
- Turnera Scabra Millsp. [excluded]
- Turnera - Turnera L.
- Turnera Ulmifolia L. var. intermedia Urb.
- Turnip-root Chervil - Chaerophyllum Bulbosum L.
- Turniproot - Pediomelum Cyphocalyx (A. Gray) Rydb.
- Turnor's Willow - Salix Turnorii Raup
- Turnsole Heliotrope - Heliotropium Undulatifolium Turrill
- Turpentine Bush - Ericameria Laricifolia (A. Gray) Shinners
- Turpentine Mulga - Acacia Cibaria F. Muell.
- Turpentine Tree - Syncarpia Glomulifera (Sm.) Nied.
- Turpentine Tree - Syncarpia Ten.
- Turpentine Wavewing - Pteryxia Terebinthina (Hook.) J.M. Coult. & Rose
- Turpentine Wavewing - Pteryxia Terebinthina (Hook.) J.M. Coult. & Rose var. albiflora (Torr. & A. Gray) Math
- Turpentine Wavewing - Pteryxia Terebinthina (Hook.) J.M. Coult. & Rose var. foeniculacea (Nutt. ex Torr. & A
- Turpentine Wavewing - Pteryxia Terebinthina (Hook.) J.M. Coult. & Rose var. terebinthina
- Turpentine Weed - Trichostema Laxum A. Gray
- Turpentinebroom - Thamnosma Montana Torr. & Frém.
- Turpin's Sandmat - Chamaesyce Turpinii (Boiss.) Millsp.
- Turpinia Paniculata auct. non Vent.
- Turpinia - Turpinia Vent.
- Turricula Parryi (A. Gray) J.F. Macbr.
- Turricula - Turricula J.f. Macbr.
- Turritis Drummondii (A. Gray) Lunell
- Turritis Glabra L.
- Turritis Laevigata Muhl. ex Willd.
- Turritis Mollis Hook.
- Turtleback - Psathyrotes A. Gray
- Turtleback - Psathyrotopsis Rydb.
- Turtlefat - Auerodendron Pauciflorum Alain
- Turtlegrass - Thalassia Testudinum Banks & Sol. ex Koenig
- Turtlehead - Chelone L.
- Turtleweed - Batis Maritima L.
- Turtleweed - Batis P. Br.
- Tusayan Fameflower - Phemeranthus Validulus (Greene) Kiger
- Tushar Mountain Draba - Draba Ramulosa Rollins
- Tushar Plateau Indian Paintbrush - Castilleja Parvula Rydb.
- Tushar Range Beardtongue - Penstemon Tusharensis N.H. Holmgren
- Tusilla - Dorstenia Contrajerva L.
- Tussilago Nutans L.
- Tussock Bellflower - Campanula Carpatica Jacq.
- Tussock Cottongrass - Eriophorum Vaginatum L.
- Tussock Cottongrass - Eriophorum Vaginatum L. var. spissum (Fernald) B. Boivin
- Tussock Cottongrass - Eriophorum Vaginatum L. var. vaginatum
- Tussock Dropseed - Sporobolus Diandrus (Retz.) P. Beauv.
- Tussock Grass - Poa Flabellata (Lam.) Hook. f. [excluded]
- Tussock Panicgrass - Dichanthelium Cynodon (Reichardt) C.A. Clark & Gould
- Tussock Paspalum - Paspalum Quadrifarium Lam.
- Tutwiler's Spleenwort - Asplenium Tutwilerae B.R.Keener & L.J.Davenp.
- Twayblade - Listera R. Br.
- Twayblade - Listera ×veltmanii Case
- Tweedy's Cat's Ear - Hypochaeris Brasiliensis (Less.) Benth. & Hook. ex Griseb. var. tweediei (Hook. & Arn.) B
- Tweedy's Fleabane - Erigeron Tweedyi Canby
- Tweedy's Gila - Gilia Tweedyi Rydb.
- Tweedy's Ivesia - Ivesia Tweedyi Rydb.
- Tweedy's Milkvetch - Astragalus Tweedyi Canby
- Tweedy's Plantain - Plantago Tweedyi A. Gray
- Tweedy's Pussypaws - Cistanthe Tweedyi (A. Gray) Hershkovitz
- Tweedy's Reedgrass - Calamagrostis Tweedyi (Scribn.) Scribn. ex Vasey
- Tweedy's Rush - Juncus Tweedyi Rydb.
- Tweedy's Sandwort - Arenaria Fendleri A. Gray var. tweedyi (Rydb.) Maguire
- Tweedy's Snowlover - Chionophila Tweedyi (Canby & Rose) L.F. Hend.
- Tweedy's Ticktrefoil - Desmodium Tweedyi Britton
- Tweedy's Willow - Salix Tweedyi (Bebb ex Rose) C.R. Ball
- Twelfth Rush - Juncus Uncialis Greene
- Twigrush - Machaerina Falcata (Nees) Koyama
- Twigrush - Machaerina Vahl
- Twin Arnica - Arnica Sororia Greene
- Twin Clover - Trifolium Latifolium (Hook.) Greene
- Twin Desertdandelion - Malacothrix Similis W.S. Davis & P.H. Raven
- Twinberry Honeysuckle - Lonicera Involucrata (Richardson) Banks ex Spreng.
- Twinberry Honeysuckle - Lonicera Involucrata (Richardson) Banks ex Spreng. var. involucrata
- Twinberry Honeysuckle - Lonicera Involucrata (Richardson) Banks ex Spreng. var. ledebourii (Eschsch.) Zabel
- Twinberry - Myrcianthes Fragrans (Sw.) McVaugh
- Twinbugs - Dicoria Torr. ex A. Gray
- Twincrest Onion - Allium Bisceptrum S. Watson
- Twincrest Onion - Allium Bisceptrum S. Watson var. bisceptrum
- Twinevine - Funastrum Fourn.
- Twinflower - Linnaea Borealis L.
- Twinflower - Linnaea Borealis L. ssp. americana (Forbes) Hultén ex R.T. Clausen
- Twinflower - Linnaea Borealis L. ssp. borealis
- Twinflower - Linnaea L.
- Twinflower Sandwort - Minuartia Obtusiloba (Rydb.) House
- Twining Bluehood - Oxyrhynchus Volubilis Brandegee
- Twining Screwstem - Bartonia Paniculata (Michx.) Muhl.
- Twining Screwstem - Bartonia Paniculata (Michx.) Muhl. ssp. iodandra (B.L. Rob.) J.M. Gillett
- Twining Screwstem - Bartonia Paniculata (Michx.) Muhl. ssp. paniculata
- Twining Snakelily - Dichelostemma Volubile (Kellogg) A. Heller
- Twining Snoutbean - Rhynchosia Tomentosa (L.) Hook. & Arn.
- Twining Snoutbean - Rhynchosia Tomentosa (L.) Hook. & Arn. var. mollissima (Elliott) Torr. & A. Gray
- Twining Snoutbean - Rhynchosia Tomentosa (L.) Hook. & Arn. var. tomentosa
- Twining Soldierbush - Tournefortia Volubilis L.
- Twinleaf Bedstraw - Galium Bifolium S. Watson
- Twinleaf - Jeffersonia Diphylla (L.) Pers.
- Twinleaf Onion - Allium Anceps Kellogg
- Twinleaf Senna - Senna Bauhinioides (A. Gray) Irwin & Barneby
- Twinpod - Physaria (nutt. ex Torr. & A. Gray) A. Gray
- Twinsorus Fern - Diplazium Sw.
- Twintip - Stemodia L.
- Twisselmann's Buckwheat - Eriogonum Twisselmannii (J.T. Howell) Reveal
- Twisselmann's Threadplant - Nemacladus Twisselmannii J.T. Howell
- Twist-stem Spikerush - Eleocharis Torticulmis S.G. Sm.
- Twisted Airplant - Tillandsia Flexuosa Sw.
- Twisted Cleomella - Cleomella Plocasperma S. Watson
- Twisted Draba - Draba Incana L.
- Twisted Sedge - Carex Torta Boott ex Tuck.
- Twisted Spikerush - Eleocharis Tortilis (Link) Schult.
- Twistedhair Spikemoss - Selaginella Tortipila A. Braun
- Twistedstalk - Streptopus Lanceolatus (Aiton) Reveal
- Twistedstalk - Streptopus Lanceolatus (Aiton) Reveal var. curvipes (Vail) Reveal
- Twistedstalk - Streptopus Lanceolatus (Aiton) Reveal var. lanceolatus
- Twistedstalk - Streptopus Lanceolatus (Aiton) Reveal var. longipes (Fernald) Reveal
- Twistedstalk - Streptopus Lanceolatus (Aiton) Reveal var. roseus (Michx.) Reveal
- Twistedstalk - Streptopus Michx.
- Twistedstalk - Streptopus ×oreopolus Fernald (pro sp.)
- Twistflower - Streptanthus Nutt.
- Twistleaf Goldenrod - Solidago Tortifolia Elliott
- Twistleaf Yucca - Yucca Pallida McKelvey
- Twistspine Pricklypear - Opuntia Macrorhiza Engelm.
- Twistspine Pricklypear - Opuntia Macrorhiza Engelm. var. macrorhiza
- Twistspine Pricklypear - Opuntia Macrorhiza Engelm. var. pottsii (Salm-Dyck) L.D. Benson
- Two-color Orange Lichen - Caloplaca Discolor (Willey) Fink
- Two-color Rabbit-tobacco - Pseudognaphalium Biolettii Anderb.
- Two-dotted Bristle Fern - Trichomanes Bipunctatum Poir.
- Two-edged Bristle Fern - Trichomanes Bimarginatum (Bosch) Bosch
- Two-horn Bundleflower - Desmanthus Bicornutus S. Watson
- Two-leaf Cape Tulip - Moraea Miniata Andrews
- Two-leaf Vetch - Vicia Unijuga A. Braun
- Two-tone Spikerush - Eleocharis Bicolor Chapm.
- Two-vein-hickory - Acacia Binervata DC.
- Two-wing Silverbell - Halesia Diptera Ellis
- Twobristle Rockdaisy - Perityle Bisetosa (Torr. ex A. Gray) Shinners
- Twobristle Rockdaisy - Perityle Bisetosa (Torr. ex A. Gray) Shinners var. appressa A. Powell
- Twobristle Rockdaisy - Perityle Bisetosa (Torr. ex A. Gray) Shinners var. bisetosa
- Twobristle Rockdaisy - Perityle Bisetosa (Torr. ex A. Gray) Shinners var. scalaris A. Powell
- Twocarpel Dwarf-flax - Hesperolinon Bicarpellatum (H. Sharsm.) H. Sharsm.
- Twocleft Stenogyne - Stenogyne Bifida Hillebr.
- Twocolor Croton - Croton Leucophyllus Müll. Arg.
- Twocolor Horsehair Lichen - Bryoria Bicolor (Ehrh.) Brodo & D. Hawksw.
- Twocolor Monkshood - Aconitum ×bicolor Schult. (pro sp.)
- Twocolor Phacelia - Phacelia Bicolor Torr. ex S. Watson
- Twocolor Sarcogyne Lichen - Sarcogyne Bicolor H. Magn.
- Twocolor Sedge - Carex Bicolor Bellardi ex All.
- Twocrested Milkvetch - Astragalus Bicristatus A. Gray
- Twoflower Cinquefoil - Potentilla Biflora Willd. ex Schltdl.
- Twoflower Dwarfdandelion - Krigia Biflora (Walter) S.F. Blake
- Twoflower Dwarfdandelion - Krigia Biflora (Walter) S.F. Blake var. biflora
- Twoflower Dwarfdandelion - Krigia Biflora (Walter) S.F. Blake var. viridis (Standl.) Kim
- Twoflower Melicgrass - Melica Mutica Walter
- Twoflower Passionflower - Passiflora Biflora Lam.
- Twoflower Pea - Lathyrus Biflorus T.W. Nelson & J.P. Nelson
- Twoflower Rattlebox - Crotalaria Biflora L.
- Twoflower Stickpea - Calliandra Biflora Tharp
- Twoflower Violet - Viola ×viarum Pollard
- Twoflowered Rush - Juncus Biglumis L.
- Twogrooved Milkvetch - Astragalus Bisulcatus (Hook.) A. Gray
- Twogrooved Milkvetch - Astragalus Bisulcatus (Hook.) A. Gray var. bisulcatus
- Twogrooved Milkvetch - Astragalus Bisulcatus (Hook.) A. Gray var. major (M.E. Jones) S.L. Welsh
- Twoheaded Water-starwort - Callitriche Heterophylla Pursh
- Twoheaded Water-starwort - Callitriche Heterophylla Pursh ssp. heterophylla
- Twoleaf Anemone - Anemone Quinquefolia L. var. bifolia Farw.
- Twoleaf Beardtongue - Penstemon Diphyllus Rydb.
- Twoleaf Miterwort - Mitella Diphylla L.
- Twoleaf Nightshade - Solanum Diphyllum L.
- Twoleaf Senna - Senna Roemeriana (Scheele) Irwin & Barneby
- Twoleaf Sensitive Pea - Chamaecrista Diphylla (L.) Greene
- Twoleaf Springparsley - Cymopterus Coulteri (M.E. Jones) Mathias
- Twoleaf Watermilfoil - Myriophyllum Heterophyllum Michx.
- Twoleaf Waterweed - Elodea Bifoliata H. St. John
- Twoline False Foxglove - Agalinis Laxa Pennell
- Twolobe Clarkia - Clarkia Biloba (Durand) A. Nelson & J.F. Macbr.
- Twolobe Clarkia - Clarkia Biloba (Durand) A. Nelson & J.F. Macbr. ssp. biloba
- Twolobe Dutchman's Pipe - Aristolochia Bilobata L.
- Twolobe Larkspur - Delphinium Nuttallianum Pritz. ex Walp.
- Twolobe Passionflower - Passiflora Bilobata Juss.
- Twolobe Speedwell - Veronica Biloba L.
- Twolobe Spineflower - Chorizanthe Biloba Goodman
- Twolobe Spineflower - Chorizanthe Biloba Goodman var. biloba
- Twoneedle Pinyon - Pinus Edulis Engelm.
- Tworank Sedge - Carex Disticha Huds.
- Twoscale Saltbush - Atriplex Micrantha Ledeb.
- Twospike Crabgrass - Digitaria Pauciflora Hitchc.
- Twospike Fingergrass - Eustachys Floridana Chapm.
- Twospike Larkspur - Delphinium Distichum Geyer ex Hook.
- Twotipped Sedge - Carex Lachenalii Schkuhr
- Twotooth Buckwheat - Eriogonum Viridescens A. Heller
- Twotooth Sedge - Carex Serratodens W. Boott
- Tygh Valley Milkvetch - Astragalus Tyghensis M. Peck
- Tylophora R. Br.
- Tylophoron Lichen - Tylophoron Moderatum Nyl.
- Tylophoron Lichen - Tylophoron Nyl. ex Stizenb.
- Tylophoron Lichen - Tylophoron Protrudens Nyl.
- Tylosema Fassoglense (Kotschy ex Schweinf.) Torre & Hillc.
- Tylothallia Lichen - Tylothallia Biformigera (Leight.) P. James & R. Kilias
- Tylothallia Lichen - Tylothallia P. James & R. Kilias
- Tynanthus Caryophylleus (Bello) Alain
- Tynanthus - Tynanthus Miers
- Typha Angustata Bory & Chaubard
- Typha Angustifolia L. var. calumetensis Peattie
- Typha Angustifolia L. var. elongata (Dudley) Wiegand
- Typha ×bethulona Costa
- Typha ×provincialis A. Camus
- Typhalea Fruticosa (Mill.) Britton
- Typhonium Blumei Nicolson & Sivad.
- Typhonium Schott
- Tyria Myricifolia Scheele
- Tyrol Knapweed - Centaurea Nigrescens Willd.
- Tyrrell's Willow - Salix Tyrrellii Raup
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