Human existence (and that of most other organisms) depends heavily on what biologists call primary producers, which are mainly plants. Five thousand plant species have been used as food by humans, but now less than twenty feed the majority of the world's population and only three or four carbohydrate crops are staples for a the vast majority. One of the important benefits of conserving biodiversity is the wild plant gene pool which is then available to augment the narrow genetic base of these established food crops, thus providing disease resistance, improved productivity and different environmental tolerances (Plotkin, 1988; Reid et al., 1989).