| 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 |
| Tripleurospermum maritimum subsp. inodorum (L.) Appleq., 2003 |
| Tripolium Nees, 1832 |
| Tripolium caricifolium (Kunth) S. Schauer, 1847 |
| Tripolium divaricatum Nutt., 1841 |
| Tripolium pauciflorum (Nutt.) DC., 1836 |
| Trixis P. Browne, 1756 |
| Trixis adenolepis S.F. Blake, 1924 |
| Trixis alata D. Don, 1830 |
| Trixis amphimalaca Standl. & Steyerm., 1944 |
| Trixis angustifolia DC., 1838 |
| Trixis angustifolia var. latiuscula A. Gray, 1884 |