Q: Are the words sweet potato and yams interchangeable?
A: This is the season when this question gets asked most often. I took the following information from Texas A&M Extension. Hopefully, this will answer your question.
“Several decades ago when orange flesh sweet potatoes were introduced in the southern United States producers and shippers desired to distinguish them from the more traditional white flesh (potato) types. The African word “nyami” referring to the starchy, edible root of the Dioscorea genus of plants was adopted in its English form, “yam”. Yams in the U.S. are actually sweet potatoes with relatively moist texture and orange flesh. Although the terms are generally used interchangeably, the U.S. Department of Agriculture requires that the label “yam” always be accompanied by “sweet potato.”
As a main dish or prepared as a dessert, the sweet potato is a nutritious and economical food. One baked sweet potato (3 1/2 ounce serving) provides over 8,800 IU of vitamin A or about twice the recommended daily allowance, yet it contains only 141 calories making it valuable for the weight watcher. This nutritious vegetable provides 42 percent of the Recommended Daily Allowance (RDA) for vitamin C, 6 percent of the RDA for calcium, 10 percent of the RDA for iron, and 8 percent of the RDA for thiamine for healthy adults. It is low in sodium and is a good source of fiber and other important vitamins and minerals. A complex carbohydrate food source, it provides beta carotene which may be a factor in reducing the risk of certain cancers.
When buying sweet potatoes select sound, (deep orange) firm roots. Handle them carefully to prevent bruising. Storage in a dry, unrefrigerated bin kept at 55-60 degrees F. is best. DO NOT REFRIGERATE, because temperatures below 55 degrees F. will chill this tropical vegetable giving it a hard core and an undesirable taste when cooked.”
Sweet potato, Ipomoea batatas, is a dicot and a true root from the morning glory family. The flesh is moist and sweet containing high levels of beta carotene. On the other hand, yams, Dioscorea species, are monocots and the tubers are dry and starchy. Most of what is produced, grown and sold in the U.S. is the sweet potato.