Dioscorea alata, known as purple yam and many other names, is a species of yam, a tuberous root vegetable, that is bright lavender in color. It is sometimes confused with taro and the Okinawa sweet potato (Ipomoea batatas cv. Ayamurasaki). With its origins in the Asian tropics, D. alata has been known to humans since ancient times.
Because it has become naturalized throughout tropical South America, Africa, Australia, the US southeast, D. alata has many different common names from these regions. In English alone, aside from purple yam, other common names include greater yam, Guyana arrowroot, ten-months yam,water yam, white yam, winged yam, or simply yam. In other cultures and languages it is known variously as ratalu or violet yam in India, rasa valli kilangu in Tamil, kondfal (कोंदफळ) in Marathi, kachil (കാച്ചില്) in Malayalam, and khoai mỡ in Vietnam and for the Igbo people of Southern Nigeria, yam is called ji, and purple yam is known as ji abana.
Purple yam is used in a variety of desserts, as well as a flavor for ice cream, milk, Swiss rolls, tarts, cookies,cakes, and other pastries. In the Philippines, it is known as ube and is eaten as a sweetened jam called ube halayá, a popular ingredient in the iced dessert called halo-halo. In Maharashtra, the stir-fried chips are eaten during religious fasting. Purple yam is also an essential ingredient in Undhiyu.