legume, common name for any plant of the family Leguminosae, which is called also the pulse, legume, pea, or bean family. The word is often used loosely in the plural for vegetables in general. Botanically, a legume is the characteristic fruit of the pulse family plants, called also leguminous plants. It is a pod which usually splits along two sides, with the seeds attached along one of the sutures. The family Leguminosae is classified in the division Magnoliophyta, class Magnoliopsida, order Rosales.

Any of about 18,000 species in about 650 genera of flowering plants that make up the order Fabales, consisting of the single family Leguminosae, or Fabaceae (the pea family). The term also refers to their characteristic fruit, also called a pod. Legumes are widespread on all habitable continents. Leaves of many members appear feathery, and flowers are almost universally showy. In economic importance, this order is surpassed only by the grass and sedge order (Cyperales). In the production of food, the legume family is the most important of any family. The pods are part of the diet of nearly all humans and supply most dietary protein in regions of high population density. In addition, legumes perform the invaluable act of nitrogen fixation. Because they contain many of the essential amino acids, legume seeds can balance the deficiencies of cereal protein. Legumes also provide edible oils, gums, fibers, and raw material for plastics, and some are ornamentals. Included in this family are acacia, alfalfa, beans, broom, carob, clover, cowpea, lupine, mimosa, peas, peanuts, soybeans, tamarind, and vetch.

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