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
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. April 29, 2017. http://michiganflora.net/family.aspx?id=Dioscoreaceae.