The dangerous past and promising future of a poisonous but nutritious crop

The three staple crops that dominate the modern diet-corn, rice, and wheat-are familiar to Americans. The fourth place, however, is occupied by an outsider: cassava.

Although cassava is virtually unknown in temperate climates, it is an important food source in the tropics. It was domesticated 10,000 years ago on the southern edge of the Amazon basin in Brazil and spread throughout the region. With a lanky trunk several meters high, a handful of thin branches and modest, palmate leaves, it looks unremarkable. However, cassava's unassuming appearance belies an impressive combination of productivity, hardiness and diversity.