Dioscorea alata, also known as purple yam, ube, or greater yam, among many other names, is a species of yam. The tubers are usually a vivid violet-purple to bright lavender in color, but some range in color from cream to plain white. Yams (Dioscorea) are a type of tuber vegetable that originated in Asia, Africa, and the Carribean. Dioscorea alata is a species of yam commonly referred to as purple yam, ube, violet yam, or water yam.