Jack Bean

The jack bean, Canavalia ensiformis, is a legume used for both animal feed and human consumption, particularly prominent in Brazil, where it is known as feijao-de-porco, or pig bean, and it is the source of concanavalin A, a protein used in biotechnology. The plant grows as a twining vine to about a meter tall, with a deep root system that gives it drought resistance, pink-purple flowers, pods up to 36 centimeters long and notably large white seeds. It has long been eaten by indigenous peoples of arid Arizona and Mexico as both food and forage, and remains popular in parts of Asia, including Japan, though little used elsewhere; the beans carry mild toxins that boiling removes, the young leaves are also edible, and the whole plant is used as fodder, though it cannot be fed alongside urea-containing feed because the plant's urease enzyme reacts with urea to produce harmful ammonia.