| Alstonia pittieri (Donn. Sm.) A.H. Gentry, 1983 |
| Alstonieae G. Don, 1838 |
| Amblyanthera Müll. Arg., 1860 |
| Amblyanthera foliosa Müll. Arg., 1860 |
| Amblyanthera karwinskii Müll. Arg., 1860 |
| Amblyanthera mexicana Müll. Arg., 1860 |
| Amblyanthera microcalyx Müll. Arg., 1860 |
| Amblyanthera microcalyx var. leiophylla Müll. Arg., 1860 |
| Amblyanthera tubiflora (M. Martens & Galeotti) Müll. Arg., 1860 |
| Amsonia Walter, 1788 |
| Amsonia arenaria Standl., 1913 |
| Amsonia grandiflora Alexander, 1934 |
| Amsonia longiflora Torr., 1859 |
| Amsonia palmeri A. Gray, 1877 |
| Amsonia standleyi Woodson, 1928 |
| Amsonia tomentosa Torr. & Frém., 1845 |
| Amsonia tomentosa var. stenophylla Kearney & Peebles, 1939 |
| Amsonieae M.E. Endress, 2014 |
| Anartia Miers, 1878 |
| Apocynaceae Juss., 1789 |