| Chthamalia pedunculata Decne., 1844 |
| Chthamalia producta (Torr.) L.O. Alvarado & E.B. Cortez, 2021 |
| Chthamalia prostrata (Cav.) L.O. Alvarado & E.B. Cortez, 2021 |
| Chthamalia schaffneri (Hemsl. ex A. Gray) L.O. Alvarado & M.G. Chávez, 2021 |
| Chthamalia tehuacana Castañeda-Zárate, M.G. Chávez & L.O. Alvarado, 2023 |
| Cryptostegia R. Br., 1820 |
| Cryptostegia grandiflora Roxb. ex R. Br., 1820 |
| Cryptostegia madagascariensis Bojer ex Decne., 1844 |
| Cynanchum L., 1753 |
| Cynanchum (Mellichampia) (A. Gray) Woodson, 1941 |
| Cynanchum angustifolium Pers., 1805 |
| Cynanchum apocynellum (Gleason & Moldenke) Spellman, 1973 |
| Cynanchum astephanoides (A. Gray ex S. Watson) Standl., 1924 |
| Cynanchum barbigerum (Scheele) Shinners, 1951 |
| Cynanchum bonplandianum Schult., 1820 |
| Cynanchum californicum (Benth.) Moran, 1989 |
| Cynanchum chiapense (A. Gray) Standl. & Steyerm., 1947 |
| Cynanchum clausum Jacq., 1763 |
| Cynanchum cubense (A. Rich.) Woodson, 1941 |
| Cynanchum cyathiforme (Sundell) W.D. Stevens, 2000 |