The plants of the family Leguminosae, which is a subfamily
of Papilionoideae, are called legumes. The
Leguminosae family is the second most important group
of flowering plants, next only to Gramineae, and is
grown as a source of food and fodder. These are dicots
and form a symbiotic association with Rhizobium bacteria
in the form of nodules. Under good nodulation, much of
the plant's nitrogen needs can be met through biological
nitrogen fixation. The term also includes any plant of the
order Rosales that bears dry, dehiscent fruits.
Legumes are valued for their use in chemicals and
aesthetics. They are also valued as timber, browse trees and shrubs, forage crops, cover crops, green manures,
seeds, food and cooking fuel. Legumes, such as clover
and alfalfa, serve as forage crop. As vegetables, peas,
beans, etc., they offer a variety of protein-rich pods and
seeds. Grain legumes, like soybean, offer excellent
promise as an ingredient in the processed foods industry.
Legumes are often grown as filler, catch or relay crops
between cereal crops to enrich the soil with nitrogen, and
to break the disease cycle.
The legume family contains about 650 genera and
18,000 species. In terms of sheer numbers of species and
genera used by humans, legumes are by far the most
utilized family. Grain legumes not only provide a variety
to the human diet, they also supply dietary protein for
many populations lacking in animal and fish protein. In
addition, a grain legume like peanut, which fixes
atmospheric nitrogen and thereby reduces the cost of
nitrogen applications, is an excellent source of cooking
oil, margarine and salad dressings.
