The Complete Handbook of Yams

Chapter 1: Understanding Yams

If you are reading this handbook, you likely work with a product that is frequently misunderstood at its most basic level. The word "yam" is routinely applied to the orange-fleshed sweet potato in American supermarkets, but that is a different plant. The true yam is a tuber of the Dioscorea genus, a monocotyledonous plant native to Africa, Asia, and the Americas. Getting this fact straight is not mere botanical pedantry; it is the first step in making sound commercial decisions. The storage behavior, nutritional profile, pricing, and culinary use of a true yam are all distinct from those of a sweet potato. A buyer who treats them as interchangeable will lose money, and a chef who substitutes one for the other will produce a different dish than intended.

The Dioscorea genus contains over six hundred species, but only a handful are of significant commercial importance. The most widely traded globally is Dioscorea rotundata, the white yam, which is the staple crop of West Africa. Along with the closely related Dioscorea cayenensis, the yellow yam, it accounts for the overwhelming majority of global production and trade. The water yam (Dioscorea alata) is another major species, prized for its enormous tubers and tolerance of a wider range of growing conditions. You will also encounter the Chinese yam (Dioscorea polystachya), the lesser yam (Dioscorea esculenta), and the bitter yam (Dioscorea dumetorum). These species differ significantly in texture, starch content,