Yam, White

Dioscorea alata
Family: Dioscoreaceae

In the large genus of Dioscorea there are several species used as food, but none is more widely grown than D. alata, known variously as white yam and water yam. Native to tropical Asia, this perennial, twining vine produces thick, edible, tuberous roots, a staple food in many tropical regions. Tubers can reach 2 m (6 ft) in length and 40 kg (90 lb) or more in weight. There are many cultivars in countries where the yam is cultivated. Yams are peeled and cooked in various ways, including boiling, mashing and roasting. Tubers have a high starch content, but contain little else in the way of nutriÂents. They store better than many other tropiÂcal root crops. Many species of Dioscorea are poisonous, containing alkaloids which, in some instances, have medical applications.

Cultivation

Yams should be grown in full sun, in deep fertile soil that drains well. They need a plentiful water supply through the growing season. Plants are generally propagated from sections of the tuber containing a good eye, from which growth emerges. This is most often the top section of the tuber. They can also be propagated from small bulbils that develop in the leaf axils, or from cuttings. Outside the sub-tropics and tropics, grow in a warm greenhouse, in which case the best planting time is spring.