Yam

A yam is a root vegetable. It is similar to a sweet potato. The inside of a yam is white or orange. Yams are related to lilies and grasses.
Yam is the common name for some species in the genus "Dioscorea". These are perennial vines grown to eat. They are grown in Africa, Asia, Latin America, the Caribbean and Oceania. 95 percent of world's yam crop is harvested in West Africa.
Yam is a vegetable that can be cooked in many ways. It can be barbecued; roasted; fried; grilled; boiled; baked; smoked and when grated it is used in desserts.
Yam tubers can grow up to 1.5 meters (4.9 feet) in length and weigh up to 70 kilograms (154 lb) and 3 to 6 inches high. The skin is rough and hard to peel. It softens after heating. The inside ranges in color from white or yellow to purple or pink in mature yams.
Some people in the United States and Canada call the sweet potato a yam, but it is not a yam.