Heterostemma saolaense, a new species from Vietnam is described, illustrated and compared with the similar species Heterostemma maculatum. The two species differ in stem pubescence, peduncle, calyx and corolla size.
Forster, P.I. 1992. A taxonomic revision of Heterostemma Wight & Arn. (Asclepiadaceae: Stapelieae) in Australia and the western Pacific. Aust. Syst. Bot. 5(1): 71‒80.
Swarupanandan, K., N. Sasidharan and J.K. Mangaly 1989. A reconsideration of the generic circumscription of Heterostemma Wight & Arn. (Asclepiadaceae) and a new species from India. Bot. J. Linn. Soc. 101(2): 249–259.
Thammarong, W., S. Rakarcha, W. Pongamornkul and M. Rodda 2021. Heterostemma menghaiense (Apocynaceae), a new record for Laos and Thailand. Thai Forest Bulletin (Botany) 49(1): 63–65.
Tran, T.B, L.N. Han, D.V. Hai, B.H. Quang, N.T.T. Huong, B.T. Ha, T.V. Hai and M. Rodda 2020. Heterostemma cucphuongense (Apocynaceae, Asclepiadoideae), a new species from Vietnam. Phytokeys 148: 119–124.