I Didn’t Know That . . .

Q: What is the difference between a yam and a sweet potato?

A: Not much, in the American supermarket, because you are getting sweet potatoes, whichever you buy. The true yam belongs to a different plant family than the sweet potato, but most Americans rarely see one because they are not normally grown in the United States. The true yam, Dioscorea esculenta, is a tropical plant that is common in Africa. It does not grow well north of North Carolina. Although some are imported, they are not popular.

The sweet potato, Ipomoea batatas, is a member of the morning glory family. The confusion between the two arises because there are three types of sweet potato, one of which is darker gold than the others and oily rather than dry or mealy. Southern growers have marketed this type of sweet potato as a yam or Louisiana yam for decades.