Dioscorea alata

"Water yam" redirects here. For the book, see Water Yam (artist's book).

Purple Yam
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
Order:	Dioscoreales
Family:	Dioscoreaceae
Genus:	Dioscorea
Species:	D. alata
Binomial name
Dioscorea alata L.
Synonyms
List Dioscorea atropurpurea Roxb. Dioscorea colocasiifolia Pax Dioscorea eburina Lour. Dioscorea eburnea Lour. Dioscorea globosa Roxb. Dioscorea javanica Queva Dioscorea purpurea Roxb. Dioscorea rubella Roxb. Dioscorea sapinii De Wild. Dioscorea sativa Munro Dioscorea vulgaris Miq. Elephantodon eburnea (Lour.) Salisb. Polynome alata (L.) Salisb.

Dioscorea alata, known as purple yam and many other names, is a species of yam, a tuberous root vegetable. The tubers are usually bright lavender in color, hence the common name, but they may sometimes be white. It is sometimes confused with taro and the Okinawa sweet potato (Ipomoea batatas cv. Ayamurasaki), although D. alata is also grown in Okinawa where it is known as beniimo (紅芋). With its origins in the Asian tropics, D. alata has been known to humans since ancient times.

Common names

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 (இராசவள்ளிக்கிழங்கு) in Tamil, kondfal (कोंदफळ) in Marathi, kachil (കാച്ചില്‍) in Malayalam, and khoai mỡ in Vietnam. For the Igbo people of southern Nigeria, it is called ji or ji abana; while for the Yoruba people of the southwestern Nigeria, it is called isu ewura.

Malayo-Polynesian languages

*qube / *ʔube can be reconstructed as the Proto-Malayo-Polynesian word for D. alata, and words descended from it are found throughout the geographic range of this widespread language family, though in some daughter languages they are generalized or transferred to other root crops. Examples include Tagalog ube or ubi, Indonesian and Malay ubi**, Malagasy ovy**, Fijian uvi, Tongan ʻufi, Samoan ufi**, as well as Māori and Hawaiian uhi. D. alata was one of the canoe plants that the Polynesians brought with them when they settled new islands.
** Not specific to D.alata

Uses

Culinary

A piece of cake made with purple yam

Dioscorea alata tuber, the edible part of the plant.

Harvested purple yam tubers

A Philippine ube-macapuno cake roll.

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 often eaten boiled or as a sweetened jam called ube halayá; the latter is a popular ingredient in the iced dessert called halo-halo. In Maharashtra, the stir-fried chips are eaten during religious fasting. Purple yam is an essential ingredient in Undhiyu. Purple yam is a popular desert in Jaffna, Sri Lanka.

D. alata is valued for the starch that can be processed from it.

Medicinal

In folk medicine, D. alata has been used as a laxative and vermifuge, and as a treatment for fever, gonorrhea, leprosy, tumors, and inflamed hemorrhoids.

Other uses

D. alata is sometimes grown in gardens for its ornamental value.

Weed problems

Dioscorea alata is native to Southeast Asia (Indochina, Philippines, Indonesia, etc.) and surrounding areas (Taiwan, Ryukyu Islands, Assam, Nepal, New Guinea, Christmas Island). It has escaped into the wild in many other places, becoming naturalized in parts of China, Africa, Madagascar, the Western Hemisphere, and various islands in the Indian and Pacific Oceans. It persists in the wild in the United States in Louisiana, Georgia, Alabama, Florida, Puerto Rico, and the U.S. Virgin Islands. It is considered an invasive species, at least in Florida.

External links

• Sri Lanka Rasa Valli Pudding
• Food Glossary, tarladalal.com
• Images from Forestry Images (webpages from the University of Georgia’s Center for Invasive Species and Ecosystem Health)

•  Dioscorea alata was first described and published in Species Plantarum 2: 1033. 1753.
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• Degras, L. 1993. The Yam: A Tropical Root Crop. London, New York, and Wageningen

• Kew World Checklist of Selected Plant Families
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• Biota of North America Program, 2013 county distribution map