Legume
Legume, common name for a plant family, the only member of the third largest order of flowering plants in terms of species, with some 18,000; and the second most important economically, after the grasses. The family is worldwide in distribution, but its greatest concentration is in tropical and subtropical regions. The plants show great diversity in both vegetative and floral form; woody, perennial species predominate, but numerous herbaceous forms and even a few aquatics also occur. The fruit is the feature by which the family is best characterized. Technically known as a legume, it is a single-chambered, flattened seedpod with two sutures. It usually splits open along the two sutures, as in the common pea. The seeds are attached along one of the sutures. The legume may be indehiscent (not splitting), as in the peanut, which matures underground; or explosively dehiscent, as in broom or lupine. It also may range from only a few millimeters long to more than 30 cm (more than 12 in) and