A pulse is an annual leguminous crop yielding from one to twelve grains or seeds of variable size, shape, and color within a pod. Pulses are used for food and animal feed. The term "pulse", as used by the Food and Agricultural Organization (FAO), is reserved for crops harvested solely for the dry grain. This excludes green beans and green peas, which are considered vegetable crops. Also excluded are crops that are mainly grown for oil extraction (oilseeds like soybeans and peanuts), and crops which are used exclusively for sowing (clovers, alfalfa). Pulses are important food crops due to their high protein and essential amino acid content. Like many leguminous crops, pulses play a key role in crop rotation due to their ability to fix nitrogen. Mung bean (Hindi: ????), also known as green bean, mung, mongo, moong, moog dal (in Bengali), mash bean, munggo or monggo, green gram, golden gram, and green soy, is the seed of Vigna radiata which is native to Bangladesh, India, and Pakistan. The split bean is known as moong dal, which is green with the husk, and yellow when dehusked. The beans are small, ovoid in shape, and green in color. The English word "mung" derives from the Hindi moong. The mung bean is one of many species recently moved from the genus Phaseolus to Vigna and is still often seen cited as Phaseolus aureus or Phaseolus radiatus. These variations of nomenclature have been used regarding the same plant species.