Members of the legume family have simple, dry, pod-shaped fruits that contain dry seeds or grains. According to the USDA the legume family, called Fabaceae, is comprised of almost 22,000 specific species. Some legumes make a nutritious addition to the diet, and other show promise as medicine.
Peas are members of the legume family, which also includes a wide variety of beans. One of the main distinctions between peas and beans is that peas tend to grow in vines that require support, whereas most beans grow in self-supporting bushes. Peas also favor cooler climates than beans do.
Apart from being important as a food source, peas and other members of the legume family are capable of taking nitrogen from the air and adding it to the soil. This ability, called nitrogen fixation, is an important part of agriculture because plants require nitrogen to grow.
Because other crops need nitrogen but cannot retrieve it from the air as legumes do, many farmers alternate crops to allow a member of a legume family to replenish a field's nitrogen content.