Dioscorea alata – also called 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. It is sometimes confused with taro and the Okinawa sweet potato beniimo (紅芋), however D. alata is also grown in Okinawa. With its origins in the Asian tropics, D. alata has been known to humans since ancient times.

Yam is the common name for some plant species in the genus Dioscorea that form edible tubers.