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General description:
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Cassava is a perennial woody shrub with edible starchy roots native to South America. Today it is grown in tropical and sub-tropical areas worldwide as a major staple food. Depending on the variety, the cassava plant may grow from 1 to 2.75 meters (9 feet) tall, with leaves deeply divided into 3–7 lobes (seldom 1). Cassava is often grown as an annual and propagated from stem cuttings after roots have been harvested. Harvested roots deteriorate quickly if not processed. Roots of domesticated varieties require 6–18 months to mature and are generally 5–10 cm in diameter and 15–30 cm long. Varieties contain differing amounts of cyanide compounds that may be toxic; high cyanide varieties are termed “bitter” and low cyanide varieties “sweet”. Sweet roots can be cooked and eaten directly; bitter roots are generally soaked, grated, squeezed and roasted to reduce the cyanide and to produce cassava flour which can only then be stored.
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History, uses and importance:
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Prehistorically (perhaps 4000ybp), Amerindians of the upper Amazon River basin domesticated cassava and developed sustainable, swidden agriculture. Cassava is not rich in nutrients or protein but it has very high energy content that, when combined with hunting, fishing and harvesting of native fruits and vegetables, sustained tropical cultures with an active lifestyle. In Africa, the leaves are eaten as a vegetable after cooking, which reduces the cyanide content. The Portuguese distributed the crop around the tropics more than 400ybp. Today, commercial cassava includes dried animal feed, starch, tapioca and fresh roots, protected from deterioration by freezing or dipping in wax to avoid oxidation and bacteria. Cassava is the third most important staple in the tropics (after rice and corn), grown on approximately 25 million hectares worldwide.
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