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Sweet potatoes and common potatoes share part of a name and the spotlight at Thanksgiving meals, but the two are entirely different plants — and sweet potatoes aren’t even potatoes. While both root vegetable species are native to Central and South America, they’re classified as unrelated. Sweet potatoes belong to the Convolvulaceae family, a group of flowering plants that’s also called the morning glory family. Potatoes belong to the nightshade (Solanaceae) family, and are cousins to peppers, tomatoes, and eggplants. 

Sweet potatoes were served at the first Thanksgiving.

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The orange-fleshed tubers are typical feasting fare, but they didn’t grace the holiday spread at the first Thanksgiving in 1621. That’s because sweet potatoes weren’t yet grown in North America; the first known crops were planted in Virginia nearly three decades later in 1648.

Both species get their name from an Indigenous Caribbean term, batata, which eventually morphed into the English “potato.” By the 1740s, “sweet” was added to the orange-fleshed tuber’s name to differentiate the two root crops.

Then there are yams. Although they’re often served interchangeably with sweet potatoes at Thanksgiving dinners, this third root crop is biologically unrelated to either sweet potatoes or common potatoes. These tubers belong to the Dioscoreacea family, a group of flowering plants usually cultivated in tropical areas. Luckily, you don’t have to know their scientific classification to distinguish between the two nonspuds at the grocery store: Sweet potatoes have tapered ends and relatively smooth skin, while true yams are generally larger with rough bark and a more cylindrical shape. At most U.S. grocery stores, what you’re seeing labeled as a yam is probably actually a sweet potato.

Numbers Don't Lie

Numbers Don't Lie

Weight (in pounds) of the world’s heaviest sweet potato (Spain, 2004)
81.5
Varieties of sweet potatoes
400+
Approximate weight (in pounds) of the largest sweet potato pie (Japan, 2018)
703
Year the first marshmallow-topped sweet potato recipe appeared
1917

Some 60% of American sweet potatoes are grown in ______.

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Some 60% of American sweet potatoes are grown in North Carolina.

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George Washington Carver invented more than 100 uses for sweet potatoes.

Peanuts are often considered the primary fascination of scientist George Washington Carver, who devised 325 uses for the legumes in the early 20th century, but the botanist also studied sweet potatoes extensively. In his writings, Carver advised farmers how to successfully grow the tubers and eat them, including dozens of recipes for pureed, scalloped, and baked sweet potatoes, along with desserts such as pies and doughnuts. Carver’s research included the development of sweet potato coffee, vinegar, and synthetic silk, but one of his most successful inventions was sweet potato flour, a culinary wonder that would help stretch rations amid World War I’s wheat shortage. The U.S. Department of Agriculture used Carver’s know-how to produce the wheat alternative until the war’s end; it soon after fell out of popularity, but is still available today as a gluten-free baking alternative.

Nicole Garner Meeker
Writer

Nicole Garner Meeker is a writer and editor based in St. Louis. Her history, nature, and food stories have also appeared at Mental Floss and Better Report.