Dioscoreaceae

This is the family that contains the cultivated yam, although most reference to "yams" in North America actually are to the sweet potato (Ipomoea, Convolvulaceae) 

All species found in Dioscoreaceae

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. December 13, 2017. http://www.michiganflora.net/family.aspx?id=Dioscoreaceae.