In

trifida) and winged, or water, yam (D. alata) are the edible species most widely diffused in tropical and subtropical countries. The tubers ofD. alata sometimes weigh 45 kg (100 pounds). Guinea yam (D. rotundata) and yellow Guinea yam (D. cayenensis) are the main yam species grown…

alata, the white yam of India and the Malay Peninsula, is widely cultivated for its enlarged roots. Elephant’s-foot (D. [orTestudinaria]elephantipes), grown in Africa, is used as a famine food. Roots of all these plants contain poisonous alkaloids that are destroyed by boiling. In addition, several…