cassava

Plant belonging to the spurge family. Native to South America, it is now widely grown throughout the tropics for its starch-containing roots, from which tapioca and bread are made. (Manihot utilissima, family Euphorbiaceae.)

Cassava is grown as a staple crop in rural Africa, Asia, and South America. Altogether, it provides a staple crop for approximately 200 million people. The root cells contain the poison cyanoglucoside (converted to hydrogen cyanide in the body) but the plant's latex (milky fluid) contains enzymes that break down the poison. During the processing of cassava the two must mix; the commonest method is by fermentation, although some poison may remain. In the Democratic Republic of Congo (formerly Zaire) and Mozambique at least 10,000 women and children suffered from chronic poisoning between 1985 and 1995.

In 1997 a new hybrid virus caused approximately $60 million in damages as it destroyed cassava crops in Uganda.