What's The Difference Between A Sweet Potato And A Yam?

Sweet potatoes in the produce section of a supermarket in VA. What's in a name? Although supermarkets offer both 'yams' and 'sweet potatoes,' in fact they are all sweet potatoes. True yams are rarely seen in the United States, and are actually quite different from the familiar sweet potato. Their skin is rough and they are sometimes enormous, weighing up to 30 pounds. Yams are native to Africa and are 'monocotyledons', like grasses and daffodils - the seedling is a straight pointy shoot.

Sweet potatoes are native to tropical America. They were first cultivated in prehistoric times by the Aztecs in Mexico, and the Spanish conquistadores introduced them to Europe in the 16th Century. Sweet potatoes are 'dicotyledons', like lima beans and oak trees - the seedling has two arms like a little helicopter rotor. They are members of the morning glory family. Sweet potatoes are extremely nutritious, high in vitamin A and beta carotene. (Yams have hardly any beta carotene.) And whether you call it a sweet potato pie or a yam pie, it's delicious!

About the Author

Sandy Becker, MA

Sandy BeckerSandy Becker received a BA in history from Pomona College. She then earned two MAs in Biology, and now has 25 years of experience in developmental biology research, working with mouse embryonic stem cells. Sandy began writing science articles about ten years ago to share her knowledge of science. She is currently studying for her third MA, in science journalism.