Sweet potatoes and yams are often grouped together into the same category: They’re round, fleshy root vegetables, a lovely orange (thanks, beta carotene!) on the inside, frequently perched next to one another in the grocery store, and both vegetables are commonly tucked into the oven to bake for roasting. But the two products yielded from the ground have different names; so what’s the difference between yams and sweet potatoes?
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“A common misconception at many American dinner tables, the sweet, orange-colored root vegetable that so many people have come to recognize and love as a yam is, in fact, a sweet potato,” says Kelly McIver, executive director of the North Carolina SweetPotato Commission. “A true yam—generally imported to America from the Caribbean—is a starchy edible root of the Dioscorea genus and is rough, scaly and very low in beta carotene.”
It’s all the result of a potato marketing ploy on the part of Louisiana sweet potato growers in the 1930s who wanted to differentiate their variety of sweet potatoes from the drier, white-fleshed varieties that were being grown on the East Coast, says Tara Smith, a sweet potato extension specialist at the Louisiana State University Agricultural Center. The potato growers chose yam, the English word that derives from West African words meaning either true yams or “to eat.” (The USDA requires that the vegetables still be identified as sweet potatoes though, so the label will say both yams and sweet potatoes.) So while many people in the U.S. use yam and sweet potato interchangeably, these two tuberous root vegetables are actually very different.
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What Is a Sweet Potato?
There are actually a wealth of sweet potatoes varieties. These tubers hail from the morning glory family. You’ll find a rainbow of skin colors—from brown, purple, red, white, and yellow—and the meaty flesh can often be found in orange and yellow.
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In the U.S., a large amount of sweet potatoes are grown, but there are two kinds that are the most popular: firm sweet potatoes and soft sweet potatoes. The difference between these two is that firm sweet potatoes are golden on the outside, boast a light flesh inside, and are a little tougher after roasting, while soft yams are bright orange inside, with a copper skin, and after cooking are very soft and creamy.
What Are True Yams?
True yams have rougher, scalier skin than sweet potatoes and are often pale-fleshed. The flesh of a yam comes in a slew of colors, from red to purple and white. They are generally starchier in texture. True yams belong to the family Dioscoreaceae, whereas sweet potatoes are in the Convolvulaceae family. Unlike sweet potatoes (which originate from Peru and Ecuador), true yams are from West Africa and Asia. One popular way to cook yams included candied yams, where the flesh of yams are sliced, mashed, and baked in the oven with butter and brown sugar.
Although sweet potatoes are ubiquitous in grocery stores, yams are much harder to come by in the United States (though Chowhounds have tried). Your best chance of finding yams is to seek out any specialty or international grocery stores.
So next time you’re perusing your grocery store and wander by the potato section, take a peak and see if you can tell the difference between a yam and sweet potato. You might be surprised what you find.
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