| Trixis turbinata (La Llave & Lex.) Sch. Bip., 1856 |
| Trixis wrightii B.L. Rob. & Greenm., 1904 |
| Troximon Gaertn., 1791 |
| Troximon heterophyllum (Nutt.) Greene, 1883 |
| Tuckermannia Nutt., 1841 |
| Tuckermannia maritima Nutt., 1841 |
| Turpinia Lex., 1824 |
| Turpinia tomentosa Lex., 1824 |
| Tussilagininae Dumort., 1827 |
| Tussilago L., 1753 |
| Tussilago nutans L., 1759 |
| Tuxtla Villaseñor & Strother, 1989 |
| Tuxtla pittieri (Greenm.) Villaseñor & Strother, 1989 |
| Ucacou Adans., 1763 |
| Uhdea Kunth, 1847 |
| Uhdea bipinnatifida Kunth, 1847 |
| Unxia L. f., 1782 |
| Unxia achillioides Less., 1830 |
| Unxia pratensis Kunth, 1818 |
| Urbananthus R.M. King & H. Rob., 1971 |