Yam is the name given to many plants with tubers belonging to the family of Dioscoreaceae.    From Wordnik.com.  [Chapter 5] Reference

The yams belong to the family Dioscoreaceae, a group of plants which, like the grasses, have one cotyledon (monocotyledons).    From Wordnik.com.  [Chapter 7] Reference

Additional sources include the page on Dioscoreaceae (Yam Family) by Professor Arthur C. Gibson of UCLA.    From Wordnik.com.  [Did You Know? Birth control pills come from Mexican yams] Reference

(Dioscoreaceae).    From Wordnik.com.  [Madagascar succulent woodlands] Reference

Dioscoreaceae.    From Wordnik.com.  [Chapter 7] Reference

Dioscoreaceae.    From Wordnik.com.  [Chapter 37] Reference

Dioscorea minutiflora Engl. Dioscoreaceae.    From Wordnik.com.  [Chapter 7] Reference