|Yams at Brixton market|
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.
Some people in the United States and Canada call the sweet potato a yam. It is not a yam.
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.