The soybean (U.S.) or soya bean (UK) (Glycine max) is a species of legume native to East Asia. It is an annual plant that may vary in growth, habit, and height. It may grow prostrate, not growing higher than 20 cm (7.8 inches), or even up to 2 meters (6.5 feet) in height. The pods, stems, and leaves are covered with fine brown or gray pubescence. The leaves are trifoliolate, having 3 leaflets per leaf, and the leaflets are 6-15 cm (2-6 inches) long and 2-7 cm (1-3 inches) broad. The leaves fall before the seeds are mature. The small, inconspicuous, self-fertile flowers are borne in the axil of the leaf and are white, pink or purple. The fruit is a hairy pod that grows in clusters of 3-5, with each pod 3-8 cm (1-3 inches) long and usually containing 2-4 (rarely more) seeds 5-11 mm in diameter.
Like some other crops of long domestication, the relationship of the modern soybean to wild-growing species can no longer be traced with any degree of certainty. It is a cultural variety (a cultigen) with a very large number of cultivars. However, it is known that the progenitor of the modern soybean was a vine-like plant that grew prone on the ground.
The genus Glycine Willd. is divided into two subgenera(species), Glycine and Soja. The subgenus Soja(Moench) includes the cultivated Soybean, G. max(L.)Merrill, and the wild soybean, G. soja Sieb.& Zucc. Both species are annual. The soybean grows only under cultivation while G. soja grows wild in China, Japan, Korea, Taiwan and Russia. Glycine soja is the wild ancestor of the soybean: the wild progenitor. At present, the subgenus Glycine consists of at least 16 wild perennial species: for example, Glycine canescens, and G. tomentella Hayata found in Australia and Papua New Guinea
Beans are classed as pulses whereas soybeans are classed as oilseeds. It is a versatile bean, having a diverse range of uses.
The English word soy is derived from the Japanese pronunciation of 醤油 (しょうゆ, shōyu), the Japanese word for soy sauce; soya comes from the Dutch adaptation of the same word.
