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Glycine spp.

soybeans

HardinessZones 9–11

Overview

Glycine spp. is a genus of about 25 legumes in the pea family, Fabaceae, that includes the cultivated soybean, G. max, one of the world's major food and oilseed crops. The genus also includes wild perennial relatives, most of them twining herbs native to Australia, with others in East Asia, Africa, and the Pacific. Soybean is an erect, bushy annual 12-60 inches (30-150 cm) tall, while the wild perennial species scramble and climb over other vegetation. All carry trifoliate leaves and small pea-shaped flowers in white, pink, or purple, followed by hairy pods holding one to several seeds. Like other legumes, Glycine spp. fixes nitrogen through root nodules and improves soil fertility. Soybean seeds are processed into oil, meal, tofu, and many other products, but the raw beans contain compounds that must be removed by cooking or processing before they are eaten. Wild species are studied as genetic resources for breeding disease resistance into the crop.

Native Range

East Asia is the origin of cultivated soybean, domesticated from the wild G. soja. Most wild perennial species are native to Australia, with others in East and Southeast Asia, Africa, and the Pacific islands.

Suggested Uses

Glycine spp. is grown chiefly as an agricultural crop for soybeans used in oil, animal feed, tofu, and many processed foods, and as a green manure and cover crop that fixes nitrogen. Wild perennial species are maintained in research and breeding collections. Soybean is sometimes grown in vegetable gardens as edamame, harvested young.

How to Identify

Recognized by trifoliate leaves with three oval leaflets, hairy stems, and small pea-shaped flowers in white to purple held in short clusters. The fruit is a flattened, hairy pod containing one to several rounded seeds. Cultivated soybean grows as an erect bush, while wild species twine and climb.

Appearance

Size & Dimensions

Height1' - 6'

Width/Spread1' - 2'

Colors

Flower Colors

Foliage Colors

Bloom Information

Bloom Period

~4 weeks

Summer

Soybean flowers in summer, with timing governed by day length, so varieties are matched to particular latitudes. The small white to purple pea flowers are self-pollinating and are followed within weeks by developing pods. Wild perennial species also flower in the warm season, over a longer and less synchronized period.

Detailed Descriptions

Flower Description

White, pink, or purple

Foliage Description

Green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.0(Neutral)

357912

Soil Types

loam sand clay

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

tender

Time to Maturity

80-150 days for the soybean crop

Care & Maintenance

Care Guide

Glycine spp. grows in full sun and warm conditions in well-drained, fertile soil with a near-neutral pH. Soybean is sown after the soil warms in spring and matures in roughly 80 to 150 days depending on variety, needing steady moisture during flowering and pod fill. Seed inoculated with the correct rhizobium bacteria forms nitrogen-fixing nodules and needs little added nitrogen. The crop is sensitive to frost at both ends of the season and to prolonged drought during pod development. Wild perennial species are more tolerant of poor soils and dry spells once established.

Pruning

Soybean grown as a field or garden crop is not pruned and is harvested whole once the pods mature and dry. Wild perennial species can be cut back to control their spread over other plants. Removing spent annual plants after harvest returns nitrogen-rich residue to the soil.