Legumes are a family of flowering plants of more than 18,000 varieties, including peas, beans, lentils and peanuts. They grow on almost every continent except Antarctica and range from dwarf herbs in alpine climes to massive trees in the tropical forest. The species that are rich in fiber, protein, iron and folic acid include chickpeas, soybeans and alfalfa. As a family, legumes or pulses are second only to grasses (cereal grains) in their economic importance in the world — and surpass grains in their nutritional value.

In Japan, the king of the legumes is the soybean, which is generally processed — into tofu or another soy product — before being eaten. However, there are several important legumes that are consumed as fresh vegetables, from late spring on through the end of the summer. The five most important are the garden or snap bean (ingenmame), the snow pea (kinusaiya), the broad or fava bean (soramame), the pod pea (endo) and the young soybean still on the branch (edamame).

The ingenmame gets its name from the priest Ingen who brought the mame (bean) from China in the 16th century. Related to the French haricot vert, snap beans are one of only two major varieties — along with the kinusaiya — of vegetable legume where the pod is consumed along with the seed. In Japan these beans are generally blanched quickly and then poached in a dashi flavored with usukuchi shoyu (light soy sauce) and a touch of mirin.