| Talayotea trachyantha (Greenm.) L.O. Alvarado, 2021 |
| Tassadia Decne., 1844 |
| Tassadia obovata Decne., 1844 |
| Tassadiinae Liede & Meve, 2014 |
| Telosiphonia (Woodson) Henrickson, 1996 |
| Telosiphonia brachysiphon (Torr.) Henrickson, 1996 |
| Telosiphonia hesperia (I.M. Johnst.) Henrickson, 1996 |
| Telosiphonia hypoleuca (Benth.) Henrickson, 1996 |
| Telosiphonia lanuginosa (M. Martens & Galeotti) Henrickson, 1996 |
| Telosiphonia macrosiphon (Torr.) Henrickson, 1996 |
| Telosiphonia nacapulensis Felger & Henrickson, 1996 |
| Thenardia Kunth, 1819 |
| Thenardia chiapensis J.K. Williams, 1995 |
| Thenardia floribunda Kunth, 1819 |
| Thenardia galeottiana Baill., 1890 |
| Thenardia gonoloboides Woodson, 1936 |
| Thenardia suaveolens M. Martens & Galeotti, 1844 |
| Thenardia tubulifera Woodson, 1932 |
| Thevetia L., 1758 |
| Thevetia ahouai (L.) A. DC., 1844 |