I Yam Not a Sweet Potato

Raise your hand if candied yams are on your Thanksgiving table. 

Let me be the one to break it to you. Most likely you’re eating sweet potatoes.

The names “yam” and “sweet potato” are often used interchangeably, but they are very different. The two plants aren’t even in the same family.

We grow sweet potates on our farm. We couldn’t grow yams if we tried.

True yams are grown in the tropical climate of the Caribbean and Africa and imported to America. It’s not often I find one in the grocery store, but I did recently. The yam I found in the produce section was grown in Peru. The sweet potato, which was marketed as a yam, was grown on a North Carolina farm. 

Fresh and canned sweet potatoes are often marketed as yams but may also be labeled as sweet potatoes. If you look at the label on a can of candied yams, the first ingredient is sweet potatoes. 

Why the confusion? When the orange flesh sweet potato variety was introduced to the United States, packers and retailers needed a way to distinguish it from a white potato, which is also not related to sweet potatoes. They used the English version of nyami, the African word for yam.  The name stuck.

So, what is the difference between a yam and a sweet potato? 

Sweet potatoes are members of the morning glory family. Almost 60% of the U.S. sweet potato crop is grown in North Carolina, so many that it was named our state vegetable. Yams belong to the Dioscoreaceae family and are related to grasses and lilies.

Both vegetables grow underground, but they are different parts of the plant. Sweet potates are the plant’s storage root.  Yams are modified stems called tubers.

Sweet potatoes have thin, smooth skin that can be brown, red, or purple. The flesh may be orange, white, or purple.  Yams have rough, scaly skin. Their flesh can be white, yellow, purple, or pink.

While sweet potatoes can be various sizes, most are short with tapered ends. Ideally, they are harvested between 8 and 20 ounces in size, about the size of my hand (pictured above holding a sweet potato on the right). Yams can be anywhere from the size of a sweet potato to 5 feet long. They can weigh a few ounces or up to 100 pounds.             

Sweet potatoes are moist and sweet while yams are starchy. Both are nutritious and versatile. Sweet potates have a low glycemic index, making them a great food for diabetics like our son.

If you need a conversation starter at Thanksgiving, now you have one. If you need a recipe using sweet potatoes for something other than a casserole or pie, visit the NC Sweet Potato Commission’s website. I recommend the Cheesy, Sweet Potato Sausage Dip!

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