| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| TUCA2 | Tuckermannopsis canadensis (Rasanen) Hale | Vulpicida canadensis | Parmeliaceae
|
| TUCH60 | Tuckermannopsis chlorophylla (Willd.) Hale | | Parmeliaceae
|
| TUCI60 | Tuckermannopsis ciliaris (Ach.) Gyelnik | | Parmeliaceae
|
| TUCO3 | Tuckermannopsis coralligera (W. A. Weber) W. A. Weber | | Parmeliaceae
|
| TUFE | Tuckermannopsis fendleri (Nyl.) Hale | | Parmeliaceae
|
| TUHA | Tuckermannopsis halei (Culb. & C. Culb.) M. J. Lai | Tuckermannopsis americana | Parmeliaceae
|
| TUIN | Tuckermannopsis inermis (Nyl.) Karnefelt | | Parmeliaceae
|
| TUJU | Tuckermannopsis juniperina (L.) Hale | Vulpicida canadensis | Parmeliaceae
|
| TUME | Tuckermannopsis merrillii (Du Rietz) Hale | Kaernefeltia merrillii | Parmeliaceae
|
| TUOA | Tuckermannopsis oakesiana (Tuck.) Hale | Allocetraria oaksiana | Parmeliaceae
|
| TUOR60 | Tuckermannopsis orbata (Nyl.) M. J. Lai | | Parmeliaceae
|
| TUPA3 | Tuckermannopsis pallidula (Tuck. ex Riddle) Hale | Ahtiana pallidula | Parmeliaceae
|
| TUPI60 | Tuckermannopsis pinastri (Scop) Hale | Vulpicida pinastri | Parmeliaceae
|
| TUPL | Tuckermannopsis playtphylla (Tuck.) Hale | | Parmeliaceae
|
| TUSE60 | Tuckermannopsis sepincola (Ehrh.) Hale | | Parmeliaceae
|
| TUSU | Tuckermannopsis subalpina (Imshaug) Karnefelt | | Parmeliaceae
|
| TUVI | Tuckermannopsis viridis (Schwein.) Hale | Vulpicida viridis | Parmeliaceae
|
| TUWE | Tuckermannopsis weberi (Essl.) | | Parmeliaceae
|
| TUCKE2 | Tuckermannopsis Gyelnik | tuckermannopsis | Parmeliaceae
|
| TUGR | Tuctoria greenei (Vasey) J. Reeder | awnless spiralgrass | Poaceae
|
| TUMU | Tuctoria mucronata (Crampton) J. Reeder | prickly spiralgrass | Poaceae
|
| TUCTO | Tuctoria J. Reeder | spiralgrass | Poaceae
|
| TUAN3 | Tuerckheimia angustifolia (Saito) Zand. | tuerckheimia moss | Pottiaceae
|
| TUERC | Tuerckheimia Broth. | tuerckheimia moss | Pottiaceae
|
| TULBA | Tulbaghia L. | wild garlic | Liliaceae
|
| TUBA | Tulipa batalinii Regel | | Liliaceae
|
| TUGE | Tulipa gesneriana L. | Didier's tulip | Liliaceae
|
| TUGR2 | Tulipa greigii Regel | | Liliaceae
|
| TUSY | Tulipa sylvestris L. | wild tulip | Liliaceae
|
| TUTA2 | Tulipa tarda Stapf | | Liliaceae
|
| TUTU | Tulipa turkestanica (Regel) Regel | | Liliaceae
|
| TULIP | Tulipa L. | tulip | Liliaceae
|
| TUAC2 | Tulipastrum acuminatum (L.) Small | Magnolia acuminata | Magnoliaceae
|
| TUCO2 | Tulipastrum cordatum (Michx.) Small | Magnolia acuminata | Magnoliaceae
|
| TUMA | Tumamoca macdougalii Rose | Tumamoc globeberry | Cucurbitaceae
|
| TUMAM | Tumamoca Rose | tumamoca | Cucurbitaceae
|
| TUTA | Tumion taxifolium (Arn.) Greene | Torreya taxifolia | Taxaceae
|
| TUPR2 | Tunica prolifera (L.) Scop. | Petrorhagia prolifera | Caryophyllaceae
|
| TUSA2 | Tunica saxifraga (L.) Scop. | Petrorhagia saxifraga | Caryophyllaceae
|
| TUVE | Tunica velutina (Guss.) Fisch. & C.A. Mey. | Petrorhagia dubia | Caryophyllaceae
|
| TUPO | Tupa portoricensis Vatke | Lobelia portoricensis | Campanulaceae
|
| TUCO | Turbina corymbosa (L.) Raf. | Christmasvine | Convolvulaceae
|
| TURBI | Turbina Raf. | turbina | Convolvulaceae
|
| TUGA | Turbinicarpus gautii (L. Benson) A.D. Zimmerman | top cactus | Cactaceae
|
| TURBI2 | Turbinicarpus Buxbaum & Backeberg | top cactus | Cactaceae
|
| TULA | Turgenia latifolia (L.) Hoffmann | broadleaf false carrot | Apiaceae
|
| TURGE | Turgenia Hoffmann | false carrot | Apiaceae
|
| TUCO4 | Turgidosculum complicatulum (Nyl.) Kohlm. & E. Kohlm. | Kohlmeyera complicatula | Mastodiaceae
|
| TUAP | Turnera aphrodisiaca Ward | Turnera diffusa | Turneraceae
|
| TUCI | Turnera cistoides L. | Piriqueta cistoides ssp. cistoides | Turneraceae
|
| TUDIA | Turnera diffusa Willd. ex J.A. Schultes var. aphrodisiaca (G.H. Ward) Urban | damiana | Turneraceae
|
| TUDID | Turnera diffusa Willd. ex J.A. Schultes var. diffusa | damiana | Turneraceae
|
| TUDI | Turnera diffusa Willd. ex J.A. Schultes | damiana | Turneraceae
|
| TUMI | Turnera microphylla Desv. | Turnera diffusa | Turneraceae
|
| TUOV | Turnera ovata Bello | Piriqueta racemosa | Turneraceae
|
| TUPU | Turnera pumilea L. | yellow alder | Turneraceae
|
| TUUL | Turnera ulmifolia L. | ramgoat dashalong | Turneraceae
|
| TURNE | Turnera L. | turnera | Turneraceae
|
| TUOC | Turpinia occidentalis (Sw.) G. Don | muttonwood | Staphyleaceae
|
| TUPA | Turpinia paniculata auct. non Vent. | Turpinia occidentalis | Staphyleaceae
|
| TURPI | Turpinia Vent. | turpinia | Staphyleaceae
|
| TUPA2 | Turricula parryi (Gray) J.F. Macbr. | common turricula | Hydrophyllaceae
|
| TURRI | Turricula J.F. Macbr. | turricula | Hydrophyllaceae
|
| TUDR | Turritis drummondii (Gray) Lunell | Arabis drummondii | Brassicaceae
|
| TUGL | Turritis glabra L. | Arabis glabra | Brassicaceae
|
| TULA2 | Turritis laevigata Muhl. ex Willd. | Arabis laevigata var. laevigata | Brassicaceae
|
| TUMO | Turritis mollis Hook. | Halimolobos mollis | Brassicaceae
|
| TUFA | Tussilago farfara L. | coltsfoot | Asteraceae
|
| TUNU | Tussilago nutans L. | Chaptalia nutans | Asteraceae
|
| TUSSI | Tussilago L. | coltsfoot | Asteraceae
|
| TYMO | Tylophoron moderatum Nyl. | | Uncertain Lichen Family
|
| TYPR | Tylophoron protrudens Nyl. | | Uncertain Lichen Family
|
| TYLOP | Tylophoron Nyl. ex Stizenb. | tylophoron | Uncertain Lichen Family
|
| TYFA2 | Tylosema fassoglense (Schweinf.) Torre & Hillc. | Bauhinia fassoglensis | Fabaceae
|
| TYBI | Tylothallia biformigera (Leighton) P. James & R. Kilias | | Lecanoraceae
|
| TYLOT | Tylothallia P. James & R. Kilias | tylothallia | Lecanoraceae
|
| TYCA | Tynanthus caryophylleus (Bello) Alain | Tynanthus polyanthus | Bignoniaceae
|
| TYPO | Tynanthus polyanthus (Bureau) Sandw. | bejuco de clavo | Bignoniaceae
|
| TYNAN | Tynanthus Miers | tynanthus | Bignoniaceae
|
| TYAN2 | Typha angustata Bory & Chaubard | Typha domingensis | Typhaceae
|
| TYANC | Typha angustifolia L. var. calumetensis Peattie | Typha angustifolia | Typhaceae
|
| TYANE | Typha angustifolia L. var. elongata (Dudley) Wieg. | Typha angustifolia | Typhaceae
|
| TYAN | Typha angustifolia L. | narrowleaf cattail | Typhaceae
|
| TYDO | Typha domingensis Pers. | southern cattail | Typhaceae
|
| TYGL | Typha �glauca Godr. (pro sp.) | | Typhaceae
|
| TYLA | Typha latifolia L. | broadleaf cattail | Typhaceae
|
| TYPHA | Typha L. | cattail | Typhaceae
|
| TYFR | Typhalea fruticosa (P. Mill.) Britt. | Pavonia fruticosa | Malvaceae
|
| TYMY | Tyria myricifolia Scheele | Bernardia myricifolia | Euphorbiaceae
|
| UDVEM | Udora verticillata (L. f.) Spreng. var. minor Engelm. ex Caspary | Elodea nuttallii | Hydrocharitaceae
|
| ULEU | Ulex europaeus L. | common gorse | Fabaceae
|
| ULGA | Ulex gallii Planch. | | Fabaceae
|
| ULEX | Ulex L. | gorse | Fabaceae
|
| ULTU | Ullucus tuberosus Loz. | ulluco | Basellaceae
|
| ULLUC | Ullucus Loz. | ullucus | Basellaceae
|
| ULAL | Ulmus alata Michx. | winged elm | Ulmaceae
|
| ULAMF2 | Ulmus americana L. var. floridana (Chapman) Little | Ulmus americana | Ulmaceae
|
| ULAM | Ulmus americana L. | American elm | Ulmaceae
|
| ULCA | Ulmus campestris L. p.p. | Ulmus glabra | Ulmaceae
|
| ULCA | Ulmus campestris L. p.p. | Ulmus procera | Ulmaceae
|
| ULCA2 | Ulmus carpinifolia auct. non Ruppius ex G. Suckow | Ulmus procera | Ulmaceae
|