| Thymophylla tenuifolia (Cass.) Rydb., 1915 |
| Thymophylla tenuiloba (DC.) Small, 1903 |
| Thymophylla tenuiloba var. tenuiloba (DC.) Small, 1903 |
| Thymophylla tenuiloba var. texana (Cory) Strother, 1986 |
| Thymophylla tenuiloba var. treculii (A. Gray) Strother, 1986 |
| Thymophylla tenuiloba var. wrightii (A. Gray) Strother, 1986 |
| Thymophylla tephroleuca (S.F. Blake) Strother, 1986 |
| Thymophylla treculii (A. Gray) Small, 1903 |
| Thyrsanthema Neck., 1790 |
| Thyrsanthema dentata Kuntze, 1891 |
| Thyrsanthema ehrenbergii (Sch. Bip.) Kuntze, 1891 |
| Thyrsanthema lyrata Kuntze, 1891 |
| Thyrsanthema nutans (L.) Kuntze, 1891 |
| Thyrsanthema runcinata (Kunth) Kuntze, 1891 |
| Thyrsanthema seemannii (Sch. Bip.) Kuntze, 1891 |
| Thyrsanthema spathulata (D. Don) Kuntze, 1891 |
| Thyrsanthema tomentosa (L. f.) Kuntze, 1891 |
| Timanthea Salisb., 1796 |
| Timanthea tristis Salisb., 1796 |
| Tithonia Desf. ex Juss., 1789 |