Yam is the common name for some plant species in the genus Dioscorea (family Dioscoreaceae) that form edible tubers. Yams are perennial herbaceous vines cultivated for the consumption of their starchy tubers in Africa, Asia, Latin America, the Caribbean, and Oceania. The tubers themselves are also called "yams". There are many different cultivars of yams. Although some varieties of sweet potato (Ipomoea batatas) are also called "yam" in parts of the United States and Canada, the sweet potato is not part of the family Dioscoreaceae, but belongs in the unrelated morning glory family Convolvulaceae.