So, what exactly is a legume? Legumes are defined as the long seedpod, or edible portion, of a leguminous plant. Included in the legume family are nuts, peas, lentils, and beans. Beans are the most common variety of legumes and include black beans, soybeans, garbanzo beans, kidney beans, and lima beans. They are high in protein and carbohydrates, but low in fat, and foodies appreciate them for their healthy but filling servings.