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Yams vs. Sweet Potatoes: What's the Difference? What Is a Yam? | The Old Farmer's Almanac

How Are Yams and Sweet Potatoes Different?

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What's the Difference Between Yams and Sweet Potatoes?

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Are sweet potatoes the same as yams? No… and yes. When orange sweet potatoes were first introduced, grocery stores called them “yams.” Why the confusion? Let’s get to the root of this matter—and give you the scoop on the difference between yams and sweet potatoes! 

How Are Yams and Sweet Potatoes Different?

Yams and sweet potatoes are often confused for each other. Literally and botanically speaking, the two are not related. 

Both the yam and the sweet potato DO grow underground and have yellowish-orange flesh, but there the similarity ends; they are not the same plant species.

Yams vs. Sweet Potatoes

What are yams

  • Yams are big edible “tubers” that are categorized as monocots (plants having one embryonic seed leaf) and belong to the genus Dioscorea.
  • Yams grow in tropical and subtropical climates, primarily in South America, Africa and the Caribbean. According to horticulturist U. P. Hedrick, the word “yam” comes from nyami, meaning “to eat” in Fulani—one of the many languages spoken in Guinea.
  • Yams can reach two to three feet long and some can weigh as much as 80 pounds! Imagine bringing home a yam that big from the market!
  • Real yams have rough, brown, scaly skin and white flesh that is dry and starchy; however, when cooked properly, yams have a mild, earthy flavor with a subtle sweetness. (Note: Most yams are mildly toxic when raw and must be cooked prior to consumption.)
  • Yams are very nutritious, offering carbs, fiber, potassium, vitamin C, vitamin B6, and vitamin E. In addition, tubers keep 4 to 6 months when stored properly.

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Image: Yams versus sweet potatoes. Credit: https://ncsweetpotatoes.com/

What are sweet potatoes?

  • Sweet potatoes are edible “roots” that are categorized as dicots (plants having two embryonic seed leaves) and are from the Convolvulaceae or morning glory family.
  • They are native to the Americas, growing best in both tropical and warm temperate regions. The sweet potato has long been a favorite crop in the United States, especially in the Southeast. Over 50% of the country’s sweet potatoes are grown in North Carolina.
  • In terms of size, sweet potatoes are generally about 5 inches long and weighing 4.5 ounces; they always taper at the end and have thin skin. Sweet potatoes store in the pantry for about 2 to 3 weeks; never put them in the refrigerator, as they’ll get hard and develop an unpleasant taste.
  • Sweet potato varieties come in different colors (orange, white, yellow, or purple) and have a naturally sweet, creamy, moist texture. Often, it’s served as a colorful side dish, especially around Thanksgiving.
  • Sweet potates are very nutritous, containing protein, calcium, iron, sodium, vitamin A, and beta-carotene.

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Image: Four different kinds of sweet potatoes: Jewell, Jersey, Oriental, Garnet

So, Why Do People Call Sweet Potatoes “Yams”?

Why is the orange-fleshed sweet potato variety that we commonly eat today called a “yam” when it’s not the same plant species? How did this start?

The two became entwined in this country by household vernacular, in part, through the work of a publicity campaign. Earlier this century, sweet potatoes were only white or yellow. The orange sweet potato was cultivated in the 1930s and it was larger, sweeter, more moist, and fleshier compared to the smaller, yellowish, and drier-fleshed varieties. A superior sweet potato!

To differentiate the orange sweet potato from the white and yellow ones, it was called a “yam” because it looked similar to the African vegetable. 

Today, the name “yam” has stuck as an interchangeable term for orange sweet potatoes in America. Whether you do find white, orange, yellow, or even purple sweet potatoes, they are all interchangeable in cooking, but bring different tastes, textures, and colors to your plate.

The Verdict?

Whatever you call it, you are mostly likely buying a sweet potato in your grocery store, unless you shop in a specialty or international market.

Interestingly, the U.S. Department of Agriculture requires labels with the term “yam” to be accompanied by the term “sweet potato.” Also, the preferred wording from the state sweet potato commissions seems to be “sweetpotato” (one word). Apparently, the reasoning is that it’s a unique crop, not a potato that happens to be sweet (sweet potatoes aren’t related to potatoes, either—but that’s another story). 

However, if you want to call this vegetable a “sweet potato” or a “sweetpotato” or a “yam” out of long tradition, be our guest! We know our Southern readers love their candied yams!

We hope that you enjoyed learning the “root” history of this orange, nutritious, delicious vegetable.

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Sweet potatoes are often cooked as side dishes; for example, see our popular Pecan-Crusted Sweet Potato Casserole.

See our favorite sweet potato recipes including sweet potato souffles, sweet potato pie, sweet potato fries, and more! 

Trying to grow sweet potatoes? Check out our Sweet Potato Growing Guide for tips!

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