This large edible tuber belongs to the morning-glory family and is native to tropical areas of the Americas. There are many varieties of sweet potato but the two that are widely grown commercially are a pale sweet potato and the darker-skinned variety Americans tagged "yam" to distinguish it from its lighter-fleshed kin. In actuality, the true yam is not related to the sweet potato at all. The pale sweet potato has a thin, light yellow skin and a light yellow flesh. Its flavor is not sweet and after being cooked, it has a dry and crumbly texture, much like that of a white baking potato. The darker sweet potato (the most common varieties being Beauregard and Garnet) has a thicker skin which can range in color from dark orange to pale red. The flesh, which is sweeter and moister than the pale variety, can vary in color from vivid to deep orange. Fresh sweet potatoes are available year-round, with a peak season in the winter months. When buying fresh sweet potatoes choose those that are relatively small to medium in size with smooth, unbruised skins. Sweet potatoes don't store well unless the environment is just right, which is dry, dark and around 55°F. Under perfect conditions they can be stored for three to four weeks. Otherwise, store in a cool, dark place and use within a week of purchase. Do not refrigerate. Sweet potatoes particularly the pale variety can be substituted for regular potatoes in most recipes. They can be prepared in a variety of ways including baking, boiling and sautéing. Sweet-potato chips can now be found on some restaurant menus. Canned and frozen sweet potatoes are available year-round and are often labeled as yams. Sweet potatoes are high in vitamins A and C.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.