Common bean

Phaseolus vulgaris, the common bean, is an herbaceous annual plant domesticated independently in ancient Mesoamerica and the Andes, and now grown worldwide for its edible bean, popular both dry and as a green bean. The leaf is occasionally used as a leaf vegetable, and the straw is used for fodder. Beans, squash and maize constituted the "Three Sisters" that provided the foundation of Native American agriculture. Botanically, the common bean is classified as a dicotyledon. Beans are legumes, so acquire their nitrogen through an association with rhizobia, a species of nitrogen-fixing bacteria. 18.3 million tonnes of dry common beans and 6.6 million tonnes of green beans were grown worldwide in 2007. The other major type of bean is the...