Glycine max (L.) Merr.

Herbs annual, 0.3-0.9 m tall. Stems robust, erect, some­times ± twining at apex, ± ribbed, densely brown hirsute. Leaves usually pinnately 3-foliolate; stipules broadly ovate, 3-7 mm, acuminate, densely yellow villous; petiole 2-20 cm, sparsely pubescent or hirsute when young; stipels lanceolate, 1-2 mm; petiolules 1.5-4 mm, hirsute; leaflets papery, broadly ovate, al­most circular, or elliptic-lanceolate, terminal one larger, 5-12 × 2.5-8 cm, base broadly cuneate or rounded, apex acuminate or ± rounded, mucronate; lateral leaflets smaller, obliquely ovate. Raceme short or long; peduncle 1-3.5 cm; bracts lanceolate, 2-3 mm, strigose. Flowers few to many, those on lower part of stem sometimes solitary or 1 pair between 2 axils; bracteoles lanceolate, 2-3 mm, hirsute. Calyx 4-6 mm, densely long hir­sute and strigose, usually 2-lipped; lobes 5, lanceolate, upper 2 connate to above middle, lower 3 separate, all densely white villous. Corolla purple, light purple, or white, 4.5-8(-10) mm; standard obovate-suborbicular, base clawed, apex slightly emar­ginate and usually reflexed; wings crenate, base narrow, with claws and auricles; keels obliquely obovate, with short claws. Ovary with undeveloped glands at base, hairy. Legume succu­lent, oblong, slightly curved, pendulous, 40-75 × 8-15 mm, densely silky hairy. Seeds 2-5, elliptic, suborbicular, or ovate to oblong, ca. 10 × 5-8 mm, many colored; testa smooth; hilum obvious, elliptic. Fl. Jun-Jul, fr. Jul-Sep. 2n = 40.

It is a temperate plant. It suits lowland areas. It can be grown from sea level to 2,100 m altitude. Many varieties will not flower in the tropics (short days). It needs fertile soil. The best soil acidity is pH 5.5 to 7.0. It is damaged by frost. In Nepal it grows to 1800 m altitude. It suits hardiness zones 7-8. In Yunnan.

The young pods and ripe seeds are eaten. They are used for flour. The dried seeds are boiled or baked and used in soups, stews and casseroles. The seeds are used for oil. Toasted seeds are eaten like a snack. Strongly roasted seeds are used for coffee. Soy flour is used for noodles, pasta, confectionary and other foods. The beans are fermented and used in a range of foods. Sometimes the young leaves are eaten. The seeds are also used for sprouts and for making cooking oil and soya sauce etc. Because soybean contains a trypsin inhibitor they should be cooked and even the sprouts should be lightly cooked.

It is grown from seed. Seeds need to be inoculated with bacteria before planting. The correct one is Bradyrhizobium japonicum. Plants need to be about 20 cm apart.