| Thinopyrum Á. Löve, 1980 |
| Thinopyrum intermedium (Host) Barkworth & D.R. Dewey, 1985 |
| Thinopyrum pycnanthum (Godr.) Barkworth, 1998 |
| Thrasya Kunth, 1815 |
| Thrasya (Kunth) Benth. & Hook. f., 1883 |
| Thrasya campylostachya (Hack.) Chase, 1911 |
| Thrasya ciliatifolia Swallen, 1943 |
| Thrasya gracilis Swallen, 1943 |
| Thrasya petrosa (Trin.) Chase, 1911 |
| Thrasya villosa Hitchc., 1927 |
| Thurberia Benth., 1881 |
| Thyridostachyum Nees, 1836 |
| Thysanachne C. Presl, 1829 |
| Thysanachne peruviana J. Presl, 1830 |
| Thysanachne scoparia J. Presl, 1829 |
| Tinaea Garzia, 1838 |
| Torgesia Bornm., 1913 |
| Torresia Ruiz & Pav., 1794 |
| Tosagris P. Beauv., 1812 |
| Tosagris agrostoidea P. Beauv., 1812 |