Stellenbosch University Botanical Garden, South Africa

Common name: purple yam

Family: Dioscoreaceae (Yam)

Distribution: Naturalized throughout tropical South America, Africa, Australia

Habitat: Not known in the wild, probably developed in cultivation inrobably arose in cultivation in E. Asia - Malaysia

Life form: Geophyte (bulb, corm or tuber - seasonally dormant)

Usage: Food crop

Comments: The edible tubers have a slightly sweet, earthy and nutty taste, like sweet potatoes or taro. Violet cultivars turn food distinctively purple due to the high amount of anthocyanins. Purple yams are also valued for processed starch production. Modern purple yam is most associated with Philippine cuisine (where it is known as ube or ubi), used for a variety of Philippine desserts, such as ube cake, ube cheesecake and ube crinkles, as well as an ingredient or flavor for ice cream, milk, donuts, tarts, jam and pastries. In South Africa they are occasionally sold in markets to supply demand from other African communities where it is a traditional food.
Dioscorea alata is one of various species of yams that were domesticated and cultivated independently across the islands of Southeast Asia and New Guinea for their starchy tubers, and one of the most important staple crops in Austronesian culture,
D. alata and D. esculenta were suitable for long transport on ocean trips and carried throughthe range of the Austronesian expansion. D. alata in particular, were introduced into the Pacific Islands and New Zealand, and to Madagascar and the Comoros.
The center of origin is unknown, but archaeological evidence suggests that it was used in Island Southeast Asia and New Guinea before the Austronesian expansion. Purple yam is believed to be a true cultigen, only known from its cultivated forms. Most cultivars are sterile, and without seed the presence is a good indicator of human movement.
Based on archaeological evidence of early farming plots and plant remains in the Kuk Swamp site, it seems that it was first domesticated in the highlands of New Guinea from around 10,000 years ago and spread into Island Southeast Asia via the Lapita culture from 4,000 years ago, along with D. nummularia and D. bulbifera. There is evidence of an agricultural revolution during this period brought by innovations from contact with Austronesians, including the development of wet cultivation.
Purple yam can be an invasive species.