Is that a Yam or Sweet Potato? What’s the Difference?

Sweet Potato or Yam?

Do you find yourself using the terms sweet potato and yam interchangeably? Join the club…

What you need to know:

We’ll start with the bottom line. If you live in the US and buy your groceries in a supermarket, you are most likely buying sweet potatoes.

Yams and sweet potatoes are actually 2 different species of the angiosperm (flowering plant) family. According to the records of the Library of Congress:

Yams are a monocot (a plant having one embryonic seed leaf) and from the Dioscoreaceae or Yam family. Sweet Potatoes, often called ‘yams’, are a dicot (a plant having two embryonic seed leaves) and are from the Convolvulacea or morning glory family

Yams have their roots (pun intended) in Africa and Asia, where hundreds of varieties are cultivated and eaten as a staple. “Yam” means “to eat” in various African languages / dialects.

So how did sweet potatoes come to be called yams?

There are 2 major types of sweet potatoes in the US, the lighter colored more round variety, and the orange elongated variety. In colonial times, African slaves brought to the Americas mistakenly identified the latter as the “yam” from back home. Fast forward a few hundred years, the USDA decided to formally differentiate the 2 varieties of sweet potato by calling the darker orange ones yams, thus perpetuating the tradition from the late 17th century.

And what do real yams look like? Here’s an example:

Real Yam

  • Bill Back

    Thanks. My wife and I have long been trying to figure out the difference. We even see the same sweet potato marked differently at different stores. Very confusing.

  • Heidi Hall

    i knew that they were both sweet potato, but i did not know the bit about “real” yams and what they actually look like. quite interesting!

  • Lauren

    Most important! the beta-carotene powerhouse is only in the real sweet potato, not the true yam which tends to be found in stores that import from west Africa or the Caribbean

  • Ken

    are both varieties of sweet potato nutritionally comparable?

    • Fooducate


  • Jason Wittman

    The Library of Congress, not withstanding, it seems to me that since the red variety have been called yams since the slave times, I would think that that would establish its true U.S. name as “Yams.” To me there needs to be a distinction between the two because they are like nite and day in moistness and sweetness with the yams trumping the pale blond sweet potato hands down!

  • Janet Lancaster

    So in the U.S. we pretty much have sweet potatoes…?

  • Gus

    some supermarkets carry something called “name” its usually in the exotic or tropical section, this is what a true yam is

  • Pingback: Healthy Diet Foods from the Jungle: Amazonian Inspirations for Menus – – Rainforest Meals for Weight Loss

  • Pingback: Sweetly Spiced Sweet Potato Bread | bex bakes and cakes