| Tridax serboana B.L. Turner, 2008 |
| Tridax tamaulipana B.L. Turner, 2016 |
| Tridax tenuifolia Rose, 1895 |
| Tridax trilobata (Cav.) Hemsl., 1881 |
| Tridax yecorana B.L. Turner, 1996 |
| Trigonospermum Less., 1832 |
| Trigonospermum adenostemmoides Less., 1832 |
| Trigonospermum alexandri Rzed. Calderón & Pérez-Calix, 2008 |
| Trigonospermum annuum McVaugh & Lask., 1972 |
| Trigonospermum auriculatum B.L. Turner, 1978 |
| Trigonospermum blakei McVaugh & Lask., 1972 |
| Trigonospermum floribundum Greenm., 1903 |
| Trigonospermum hintoniorum B.L. Turner, 1995 |
| Trigonospermum hispidulum S.F. Blake, 1929 |
| Trigonospermum melampodioides DC., 1836 |
| Trigonospermum tomentosum B.L. Rob. & Greenm., 1896 |
| Trimetra Moc. ex DC., 1838 |
| Tripleurospermum Sch. Bip., 1844 |
| Tripleurospermum inodorum (L.) Sch. Bip., 1844 |
| Tripleurospermum maritimum (L.) W.D.J. Koch, 1845 |