Dioscorea

1. Plants lacking bulbils in leaf axils, rhizomatous; leaves entire.

D. villosa

1. Plants producing brownish bulbils in some leaf axils, tuberous; leaves shallowly three-lobed.

D. polystachya

All species found in Dioscorea

Dioscorea polystachya CHINESE YAM 
Dioscorea villosaWILD YAM 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. September 20, 2017. http://michiganflora.net/genus.aspx?id=Dioscorea.