| Thysanocarpus rigidus (Munz) P. J. Alexander & Windham, 2010 |
| Thysanocarpus trichocarpus Rydb., 1903 |
| Tomostima Raf., 1825 |
| Tomostima cuneifolia (Nutt.) Al-Shehbaz, M. Koch & Jordon-Thaden, 2012 |
| Tomostima platycarpa (Torr. & A. Gray) Al-Shehbaz, M. Koch & Jordon-Thaden, 2012 |
| Tomostima sonorae (Greene) Al-Shehbaz, M. Koch & Jordon-Thaden, 2012 |
| Tonguea Endl., 1841 |
| Tricholobos Turcz., 1854 |
| Trochiscus O.E. Schulz, 1933 |
| Tropidocarpum Hook., 1836 |
| Tropidocarpum dubium Davidson, 1894 |
| Tropidocarpum gracile Hook., 1836 |
| Tropidocarpum gracile var. dubium (Davidson) Jeps., 1925 |
| Tropidocarpum gracile var. scabriusculum (Hook.) Greene, 1891 |
| Tropidocarpum macrocarpum Hook. & Harv. ex Greene, 1895 |
| Tropidocarpum scabriusculum Hook., 1837 |
| Turritideae Buchenau, 1894 |
| Turritis Adans., 1763 |
| Turritis L., 1753 |
| Turritis glabra L., 1753 |