Yam, any of several plant species of the genus Dioscorea (family Dioscoreaceae) grown for their edible tubers. Yams are native to warmer regions of both hemispheres, and several species are cultivated as staple food crops in the tropics. In certain tropical cultures, notably in West Africa and New Guinea, the yam is the primary agricultural commodity and the focal point of elaborate rituals. Yams are consumed as cooked starchy vegetables. They are often boiled and then mashed into a sticky paste or dough, but they may also be fried, roasted, or baked in the manner of potatoes or sweet potatoes, which are unrelated.