Yams    A tuber vegetable. Also called a Chinese potato. Some say it originated in the West Indies other believe it came from Asia true yams look nothing like sweet potatoes, nor  are they related. There are roughly six hundred species of true yams spread throughout the world's warm countries are all members the genus Dioscoria. The name yam is derived from the West African name that came into the Spanish language as name, French igname, and Portuguese as inhame.  One believes that the slaves brought the name to America and applied it to the sweet potato because they were also a root vegetable.  The D. elephantipes or Hottentot bread that grows in in the desserts of South Africa  can reach 700 pounds and the winged or water yam known world wide can reach 6 feet in length and weigh 150 pounds.  It is a large, fleshy tuber, always boiled before it is mashed or baked. It can be used successfully in place of the white potato baked (though less flavorful than the sweet potato) in its shell Canned halves in syrup are also available.