The edible tubers of a tropical and subtropical climbing plant, and the staple food of many countries, particularly South and Central America, West Indies, Africa and the Pacific Islands. Strictly speaking, yams are the tubers of one family, but the word is often used loosely to encompass a range of other tropical roots such as sweet potato, taro and cassava. In the United States, sweet potatoes are called yams. There are many varieties and these vary in size, colour and shape. Some have a coarse skin, others smooth, while some may be pale, brown or purple in colour. The flesh colour also varies, from white to cream, yellow, pink or purple. Yams are cooked as for potatoes, which they resemble in flavour, though they are more starchy and mealy. Yams must be cooked before eating to destroy the bitter toxic substance (dioscorine) that they contain. They may be boiled, puréed, baked, added to soups and stews and deep–fried. Store in a cool, dark and well–ventilated place.