Fabaceae: Strophostyles leiosperma
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Family Name
Fabaceae
Common Name
Slick-seed fuzzybean, smooth-seed wild bean
Native American Name
Lakota: omníča hú
Description
Strophostyles leiosperma is an annual or short-lived perennial, herbaceous vine with a slender, twining or trailing form. It grows from a taproot. Vines typically reach 30 to 120 cm in length and may climb or sprawl over adjacent vegetation. Stems are thin, green to purplish, and covered with fine, appressed hairs. Leaves are alternate and trifoliate. Leaflets are oblong to ovate, 2–6 cm long and 1–3 cm wide, with entire to slightly lobed margins and a pointed tip. Leaf color is medium to dark green above and paler below, sometimes with sparse appressed hairs on both surfaces. Petioles are present and usually 1–5 cm long. Stipules are present at the base of the petiole, small and linear, but easily overlooked. Flowering occurs from June to September. The inflorescence is a short, axillary raceme bearing 1–6 papilionaceous (pea-like) flowers. Each flower is about 1–2 cm long. The calyx consists of five green sepals, 3–7 mm long, fused at the base with short, broad lobes and fine hairs. The corolla has five petals, with the standard (banner) petal being pink to pale purple (sometimes white), broad and slightly notched, and about 12–20 mm long; the wings and keel are smaller, pale pink to white. There are ten stamens, nine fused and one free, with white filaments and yellow anthers, typical of the pea family. The pistil is single, about 1 cm long, with a slender style and a small, capitate stigma. Fruit is a slender, straight or slightly curved pod (legume), 3–6 cm long and about 5 mm wide, green turning brown at maturity, usually from August to October. The pod splits open to reveal smooth, oval seeds (a distinguishing feature), tan to brown, about 3–4 mm long. Slick-seed fuzzybean is native to South Dakota, found mostly in the eastern and southeastern parts of the state in open woodlands, prairies, roadsides, and disturbed sites, particularly in sandy soils.
Horticulture Notes
Seed collection: Collect mature pods in late summer to early fall as they begin to dry and split; handle gently to prevent seed loss.
Seed germination: Seeds germinate readily, though a brief scarification or soaking may enhance germination rates.
Vegetative propagation: Best propagated by seed; vegetative propagation is not commonly used.
Soils: Prefers sandy or well-drained soils but tolerates a variety of substrates.
Light: Full sun to partial shade.
Water: Drought tolerant once established; prefers moderate moisture but tolerates dry periods.
Additional Notes
Slick-seed fuzzybean is valued for its nitrogen-fixing ability, improving soil fertility in degraded or sandy sites. It provides cover for small animals and attracts pollinators such as bees and butterflies.