Have you ever had a friend (imaginary or real) who went to the store to get sweet potatoes and came home with yams? Yes, it’s happened to the best of us. It might help you to know (and save your friend a trip back to the store) that yams would probably be fine—because they’re most likely sweet potatoes anyway. In the U.S., the names are often used interchangeably, although a sweet potato isn’t as sweet as a true yam, nor is it a potato. Confused? Sweet potatoes are genus Ipomoea, which is in the morning glory family and not related to regular potatoes, which are genus Solanum. “Real” yams—bigger, sweeter, starchier, and less tapered than sweet potatoes—are genus Dioscorea, tropical tubers that grow in Africa, Asia, Latin America, and the Pacific Islands, usually only found in specialty stores in the U.S.—and they can’t be used in place of sweet potatoes.
The Mid-Atlantic and South are primo places to grow sweet potatoes—er, yams. A major factor in the name switcheroo was that, in the mid-20th century, Louisiana wanted to distinguish its fine sweet potatoes from other regions, so they called them Louisiana yams.
The etymological story goes back even further. African slaves called sweet potatoes nyam or nyami (of West African origin meaning “to eat”—also a name used for the tubers of their home), which became “yam.”
At the turn of the 20th century, George Washington Carver worked to show poor black farmers ways to make means out of the soil that had been exhausted from growing cotton—he suggested peanuts and yams. Both crops thrived in the tired soil and saved many a family from starvation during the depression. That’s one reason yams are such a down-home food.
Sweet potatoes generally fall into two types: the white or yellow dry-fleshed type are higher in starch; the garnet, red, purple, or orange type have a moist quality and are higher in sugar. They caramelize exceptionally well. Light-colored sweet potatoes definitely have their uses, but the colorful ones have more beta-carotene. A highly nutritious food, whatever you call them.
Preparation: Bake in the skin; peel and bake; or broil with simple seasoning or complements of maple syrup or nut oils. Recent studies show excellent preservation of sweet potato anthocyanins with steaming.
Storage: Store in a cool dry place. Sweet potatoes/yams should keep for 2 weeks.
Heidi Lewis writes about farms, bees, and fruit from her home in Sonoma County, CA. She's been with The FruitGuys since they were FruitKids.