Any of a large number of eudicot plants belonging to the family Fabaceae (or Leguminosae). Their characteristic fruit is a seed pod. Legumes live in a symbiotic relationship with bacteria in structures called nodules on their roots. These bacteria are able to take nitrogen from the air, which is in a form that plants cannot use, and convert it into compounds that the plants can use. Many legumes are widely cultivated for food, as fodder for livestock, and as a means of improving the nitrogen content of soils. Beans, peas, clover, alfalfa, locust trees, and acacia trees are all legumes.

The seed pod of such a plant.