Many people use the names "sweet potato" and "yam" interchangeably in conversation and in cooking, but they are really two different vegetables. Here's how to tell them apart and cook them right.
Popular in the American South, these elongated yellow or orange tubers taper to a point at each end. There are two main types. The paler-skinned sweet potato has a thin, light yellow skin and pale yellow flesh.
It's not sweet and has a dry, crumbly texture similar to a white baking potato. The darker-skinned variety (which is the tuber most often and incorrectly called a yam) has a thicker, dark orange to reddish skin with a sweet, vivid orange flesh and a moist texture.
Current popular sweet potato varieties include Goldrush, Georgia Red, Centennial, Puerto Rico, New Jersey, and Velvet.
The true yam is the tuber of a tropical vine (Dioscorea batatas) and is not even distantly related to the sweet potato. It's a popular vegetable in Latin American and Caribbean markets, with over 150 varieties available worldwide, and slowly becoming more common in the United States.
The yam tuber has a brown or black skin which resembles the bark of a tree and off-white, purple or red flesh, depending on the variety. They are at home growing in tropical climates, primarily in South America and the Caribbean, and in Africa, where they originated.
In Spanish, they are referred to as batata, boniato and ñame. Generally sweeter than the sweet potato, this tuber can grow over seven feet in length.
The yam is a much more difficult crop to harvest than the sweet potato, and it is nutritionally inferior as well. Read more about the health benefits of the sweet potato.
Yam and Sweet Potato Confusion
From the African words njam, nyami or djambi, meaning "to eat," comes the English word "yam." African slaves in the Americas began calling the indigenous sweet potato "yam" because it reminded them of the food staple they knew in Africa. For this reason, throughout the American South, the term is commonly applied to sweet potatoes.
Interestingly, the confusion is not limited to the Americas. The famed "purple yam" of Okinawa is also a sweet potato and not a true yam. In Malaysia and Singapore, "yam" refers to taro. And in New Zealand, the oca is called a yam.
More About Sweet Potatoes and Yams
The Difference Between Sweet Potatoes and Yams
Sweet Potato Selection and Storage
Sweet Potato Fact Sheet
Yam Selection and Storage
Yam Fact Sheet
Sweet Potato and Yam Health Benefits
Sweet Potato History
Sweet Potato / Yam Recipes