| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| THSUM | Thelesperma subnudum Gray var. marginatum (Rydb.) T.E. Melchert ex Cronq. | Navajo tea | Asteraceae
|
| THSUS | Thelesperma subnudum Gray var. subnudum | Navajo tea | Asteraceae
|
| THSU | Thelesperma subnudum Gray | Navajo tea | Asteraceae
|
| THTR2 | Thelesperma trifidum (Poir.) Britt. | Thelesperma filifolium var. filifolium | Asteraceae
|
| THELE | Thelesperma Less. | greenthread | Asteraceae
|
| THAS2 | Thelia asprella Sull. in Sull. & Lesq. | thelia moss | Theliaceae
|
| THHI4 | Thelia hirtella (Hedw.) Sull. in Sull & Lesq. | thelia moss | Theliaceae
|
| THLE6 | Thelia lescurii Sull. in Sull. & Lesq. | Lescur's thelia moss | Theliaceae
|
| THELI | Thelia Sull. in Sull. & Lesq. | thelia moss | Theliaceae
|
| THAB3 | Thelidium absconditum (Hepp) Rebenh. | | Verrucariaceae
|
| THAC3 | Thelidium acrotellum Arnold | Thelidium minutulum | Verrucariaceae
|
| THAE | Thelidium aeneovinosum (Anzi) Arnold | | Verrucariaceae
|
| THAR9 | Thelidium areolatum J. W. Thomson | | Verrucariaceae
|
| THCI | Thelidium circumspersellum (Nyl.) Zschacke | | Verrucariaceae
|
| THDE7 | Thelidium decipiens (Nyl.) Krempelh. | | Verrucariaceae
|
| THIN8 | Thelidium incavatum Nyl. ex Mudd | | Verrucariaceae
|
| THME4 | Thelidium mesotropum (Nyl.) A. L. Sm. | Thelidium minutulum | Verrucariaceae
|
| THMI9 | Thelidium microbolum (Tuck.) Hasse | | Verrucariaceae
|
| THMI10 | Thelidium microsporum Lynge | | Verrucariaceae
|
| THMI11 | Thelidium minimum (A. Massal. ex Korber) Arnold | | Verrucariaceae
|
| THMI12 | Thelidium minutulum Korber | | Verrucariaceae
|
| THOL2 | Thelidium olivaceum (Schaerer) Korber | | Verrucariaceae
|
| THPA12 | Thelidium papulare (Fr.) Arnold | | Verrucariaceae
|
| THPA9 | Thelidium parvulum Arnold | | Verrucariaceae
|
| THPY | Thelidium pyrenophorum (Ach.) Mudd | | Verrucariaceae
|
| THTR9 | Thelidium transsylvanicum Zschacke | | Verrucariaceae
|
| THVE6 | Thelidium velutinum (Bernh.) Korber | | Verrucariaceae
|
| THELI2 | Thelidium A. Massal. | thelidium | Verrucariaceae
|
| THLI7 | Thelignya lignyota (Wahlenb.) P. M. Jorg. & Henssen | | Lichinaceae
|
| THELI3 | Thelignya A. Massal. | thelignya | Lichinaceae
|
| THSA | Thellungiella salsuginea (Pallas) O.E. Schulz | Arabidopsis salsuginea | Brassicaceae
|
| THBIB | Thelocactus bicolor (Galeotti ex Pfeiffer) Britt. & Rose var. bicolor | glory of Texas | Cactaceae
|
| THBIF | Thelocactus bicolor (Galeotti ex Pfeiffer) Britt. & Rose var. flavidispinus Backeberg | glory of Texas | Cactaceae
|
| THBIS | Thelocactus bicolor (Galeotti ex Pfeiffer) Britt. & Rose var. schottii (Engelm.) Krainz | Thelocactus bicolor var. bicolor | Cactaceae
|
| THBI | Thelocactus bicolor (Galeotti ex Pfeiffer) Britt. & Rose | glory of Texas | Cactaceae
|
| THSE5 | Thelocactus setispinus (Engelm.) E.F. Anderson | miniature barrel cactus | Cactaceae
|
| THELO | Thelocactus (K. Schum.) Britt. & Rose | thelocactus | Cactaceae
|
| THAL6 | Thelocarpon albomarginatum Herre | Acarospora albomarginata | Acarosporaceae
|
| THEPE | Thelocarpon epibolum Nyl. var. epithallinum (Leighton ex Nyl.) Salisb. | | Acarosporaceae
|
| THEP | Thelocarpon epibolum Nyl. | | Acarosporaceae
|
| THEP3 | Thelocarpon epilithellum Nyl. | Thelocarpon laureri | Acarosporaceae
|
| THFI3 | Thelocarpon fimicola Fink | Thelocarpon intermediellum | Acarosporaceae
|
| THHA5 | Thelocarpon hassei de Lesd. | | Acarosporaceae
|
| THIN9 | Thelocarpon intermediellum Nyl. | | Acarosporaceae
|
| THLA7 | Thelocarpon laureri (Flotow) Nyl. | | Acarosporaceae
|
| THMA9 | Thelocarpon majusculum Nyl. | Thelocarpon laureri | Acarosporaceae
|
| THPR5 | Thelocarpon prasinellum Nyl. | Thelocarpon laureri | Acarosporaceae
|
| THSP3 | Thelocarpon sphaerosporum H. Magn. | | Acarosporaceae
|
| THSU5 | Thelocarpon superellum Nyl. | | Acarosporaceae
|
| THELO2 | Thelocarpon Nyl. ex Hue | thelocarpon | Acarosporaceae
|
| THCA7 | Thelomma californicum (Tuck.) Tibell | | Caliciaceae
|
| THCA8 | Thelomma carolinianum (Tuck.) Tibell | | Caliciaceae
|
| THMA8 | Thelomma mammosum (Hepp) A. Massal. | | Caliciaceae
|
| THOC60 | Thelomma occidentale (Herre) Tibell | | Caliciaceae
|
| THOC3 | Thelomma ocellatum (Korber) Tibell | | Caliciaceae
|
| THSA5 | Thelomma santessonii Tibell | | Caliciaceae
|
| THELO3 | Thelomma A. Massal. | thelomma | Caliciaceae
|
| THFA2 | Thelopsis falveola Arnold | | Stictidaceae
|
| THIN10 | Thelopsis inordinata Nyl. | | Stictidaceae
|
| THIS | Thelopsis isiaca Stizenb. | | Stictidaceae
|
| THME3 | Thelopsis melathelia Nyl. | | Stictidaceae
|
| THRU2 | Thelopsis rubella Nyl. | | Stictidaceae
|
| THSU8 | Thelopsis subporinella Nyl. | Thelopsis isiaca | Stictidaceae
|
| THELO4 | Thelopsis Nyl. | thelopsis | Stictidaceae
|
| THAB4 | Thelotrema abrosellum (Nyl.) Tuck. | barnacle lichen | Thelotremataceae
|
| THAD | Thelotrema adjectum Nyl. | barnacle lichen | Thelotremataceae
|
| THBAO | Thelotrema bahinum Ach. var. obtuascens Nyl. | Myriotrema bahianum | Thelotremataceae
|
| THCA9 | Thelotrema californicum Tuck. | California barnacle lichen | Thelotremataceae
|
| THCA12 | Thelotrema carneum Eckfeldt | Mazosia ocellata | Roccellaceae
|
| THDE8 | Thelotrema defectum Hale | defect barnacle lichen | Thelotremataceae
|
| THDI7 | Thelotrema dilatatum (Mull. Arg.) Hale | barnacle lichen | Thelotremataceae
|
| THEX | Thelotrema eximium R. C. Harris | barnacle lichen | Thelotremataceae
|
| THFL6 | Thelotrema floridense R. C. Harris | barnacle lichen | Thelotremataceae
|
| THHA6 | Thelotrema halei (Tuck. & Mont.) Zahlbr. | barnacle lichen | Thelotremataceae
|
| THHE3 | Thelotrema heterosporum C. Knight ex F. M. Bailey | Thelotrema santense | Thelotremataceae
|
| THLA8 | Thelotrema lacteum Krempelh. | barnacle lichen | Thelotremataceae
|
| THLA9 | Thelotrema lathraeum Tuck. | barnacle lichen | Thelotremataceae
|
| THLE3 | Thelotrema lepadinum (Ach.) Ach. | barnacle lichen | Thelotremataceae
|
| THLE4 | Thelotrema leprocarpum (Nyl.) Tuck. | barnacle lichen | Thelotremataceae
|
| THMO11 | Thelotrema monospermum R. C. Harris | barnacle lichen | Thelotremataceae
|
| THMO9 | Thelotrema monosporum Nyl. | Thelotrema monospermum | Thelotremataceae
|
| THPE8 | Thelotrema petractoides P. M. Jorg. & Brodo | barnacle lichen | Thelotremataceae
|
| THPL2 | Thelotrema platycarpum Tuck. | barnacle lichen | Thelotremataceae
|
| THPO13 | Thelotrema polycarpoides Tuck. | barnacle lichen | Thelotremataceae
|
| THPO12 | Thelotrema porinoides Mont. & v. d. Bosch | barnacle lichen | Thelotremataceae
|
| THPR4 | Thelotrema praestans Mull. Arg. | Ocellularia praestans | Thelotremataceae
|
| THRA3 | Thelotrema ravenelii Tuck. | Myriotrema wightii | Thelotremataceae
|
| THSA7 | Thelotrema sanfordianum Zahlbr. | Ocellularia sanfordiana | Thelotremataceae
|
| THSA6 | Thelotrema santense Tuck. | barnacle lichen | Thelotremataceae
|
| THSU6 | Thelotrema subtile Tuck. | barnacle lichen | Thelotremataceae
|
| THTE9 | Thelotrema texanum Willey ex Nyl. | Ocellularia stictidea | Thelotremataceae
|
| THELO5 | Thelotrema Ach. | barnacle lichen | Thelotremataceae
|
| THAMA | Thelypodiopsis ambigua (S. Wats.) Al-Shehbaz var. ambigua | Long Valley tumblemustard | Brassicaceae
|
| THAME | Thelypodiopsis ambigua (S. Wats.) Al-Shehbaz var. erecta Rollins | Long Valley tumblemustard | Brassicaceae
|
| THAM3 | Thelypodiopsis ambigua (S. Wats.) Al-Shehbaz | Long Valley tumblemustard | Brassicaceae
|
| THAR6 | Thelypodiopsis argillacea Welsh & Atwood | Schoenocrambe argillacea | Brassicaceae
|
| THAU3 | Thelypodiopsis aurea (Eastw.) Rydb. | Durango tumblemustard | Brassicaceae
|
| THBA3 | Thelypodiopsis barnebyi Welsh & Atwood | Schoenocrambe barnebyi | Brassicaceae
|
| THDI3 | Thelypodiopsis divaricata (Rollins) Welsh & Reveal | spreading thelypodiopsis | Brassicaceae
|
| THEL | Thelypodiopsis elegans (M.E. Jones) Rydb. | Westwater tumblemustard | Brassicaceae
|
| THJU | Thelypodiopsis juniperorum (Payson) Rydb. | juniper tumblemustard | Brassicaceae
|