We tentatively retain Vincetoxicum, following Liede & Täuber (2002) and the generic assignments in The Plant List (2013), but the generic limits in this group of Apocynaceae are still unsettled.
1. Corolla lobes pubescent above; flowering peduncles less than 2 cm long (to 2.5 cm in fruit).
1. Corolla lobes glabrous above; flowering peduncles mostly 2–2.5 cm long.
All species found in Vincetoxicum
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 13, 2017. http://michiganflora.net/genus.aspx?id=Vincetoxicum.