Sweet Potatoes and Yams


It’s a yam!

Sweet potatoes are not yams. Let’s explore the myth that they are the same thing.

Sweet potato:

  • Ipomoea batatas – scientific name
  • sweet potatoes come from the same plant family as the morning glory
  • sweet potatoes are native to the Central American region
  • they grown on a vine
  • they come in many different varieties
  • starchy roots


  • Dioscorea rotundata – scientific name
  • yams are their own plant family
  • yams are native to Africa and Asia
  • closely related to lilies or grasses
  • come in many different varieties (they actually have their own family name for “yams” which is Dioscorea)
  • starchy hard root tuber

Then how did two plants that are not near related botanically end up getting called the same thing?

I’ve found two main reasons for this perpetuation of incorrectness, both coming from very historic means.

Africa’s brought to America as slaves saw the native sweet potato and started calling them yams. Yams themselves were not that prevalent and easy to come by in northern climates so places started calling sweet potatoes “yams” to sell them as yams, and then the good ‘ol government continued the farce by labeling all sweet potatoes as yams.

Yams are a root tuber, like a ginger root, or iris roots, only on a larger scale. Yams can be as small as a traditional potato to as large as five feet in length. Sweet potatoes on the other hand don’t get much larger than a good sized baking russet potato and have tapered ends. Yams grow as tubers and sweet potatoes are more a clump of root storage system. A sweet potato vine will grow from a sweet potato scrap. I’ve never tossed a yam into my compost pile and had it grow, as I’ve never actually had yams (and thus not had the chance to toss them in my compost pile). I had a sweet potato vine pop out of on the edge of the compost pile. I had half a mind to dig it up and see what happened but it was so late in the season that it was mixed back into the pile.

This is what confuses me in todays world. We now have the ability to get yams shipped all over the world but yet sweet potatoes in a grocery store still get labeled as yams, and don’t even think about looking for an actual yam in a grocery store, they are virtually non-existant, at least in the north country where I live. I read that yams have become an invasive species in the south where the climate allows you to grow yams. Maybe in souther states you can pick up a yam at the grocer. Personally I have only ever witnessed a true yam at one grocery store, which happens to be known for it’s produce, and where I snapped the photo of yams. When I took the photo I was more surprised than anything else that they had yams for sale. They had the sweet potatoes right next to the yams.

So all those canned “yams” you’ve choked down every year at Thanksgiving have never been truly yams at all. I really want to go buy some yams, now that I know where to get them, and cook some up just to say I’ve actually had yams and can compare the difference.

But since I’ve never had yams here is the Husband’s favorite sweet potato dish

Carrie’s Sweet Potato Casserole

That is the original recipe, however that one forgets the how-to on the topping. Too bad. Here is the topping recipe:

  • 1 cup light brown sugar
  • 1/2 cup flour
  • 1/3 cup melted butter

Combine and mix well.

I double the recipe because I hate having a random 1/2 cup of evaporated milk left over. It’s light, fluffy, super sweet, and delicious. If the recipe is doubled I highly recommend a 9 x 13 pan to cut down on cooking time.


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