Last week, I realized that this self-described foodie, lover of cooking, and eater of all things delicious does not know the difference between a yam and a sweet potato.
I went to my local food co-op to pick up groceries for a recipe. The recipe instructed me to buy one large sweet potato. I only found something labeled “Conventional Yams”, and it got me thinking: do I even know the difference between a yam and a sweet potato? Are they the same thing? Do they taste different? Is it a dialect thing, where some people call them sweet potatoes and some people call them yams?
The only thing I knew for sure was that I did not know the answer to any of these questions. A perfect time for some education!
Sweet potatoes are a root vegetable that is native to tropical areas of the western hemisphere. Two varieties are sold commercially – a pale sweet potato and a darker-skinned variety that many of us in the U.S. call a “yam”. This is what I bought at the co-op. The pale sweet potato cooks much like a typical baking potato. The darker variety with the beautiful orange color inside is more moist. They are freshly available in the fall and winter months. Often, canned or frozen sweet potatoes found year round are also labeled erroneously as yams.
Yams are a tropical-vine tubor that is native to parts of Africa, Asia, Central and South America, and the West Indies, and today 95% of all yam crops are grown in Africa. They are closely related to lily and grass species and are thus a completely different species from sweet potatoes. In all, there are over 600 varieties of yam and some can grow as large as 120 pounds! Yams range from pale white to deep orange and may be dry and crumbly or more moist than a sweet potato. Although they are not sweet potatoes, yams can be substituted for sweet potatoes in most recipes. However, you will likely have to find an international market to purchase these as they are not typically sold in your neighborhood grocery store.
Food Lover’s Companion, 3rd Edition, Sharon Tyler Herbst (updated version here)
Everyday Mysteries: Fun Science Facts from the Library of Congress, What is the difference between sweet potatoes and yams?