Fabaceae : Astragalus gilviflorus

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Family Name

Fabaceae

Common Name

Plains milkvetch, plains orophaca

Native American Name

Lakota: núŋǧoka yazáŋ pȟežúta

Description

Astragalus gilviflorus is a perennial, cushion-forming, acaulescent or very short-stemmed (<3 cm long) herb, covered with silvery ax-shaped hairs. The compound, alternate, petiolate, leaves, have conspicuous, membranous or chartaceous stipules that are persistent, clasping and forming a tube or sheath around the stem. The leaves are trifoliolate, sometimes odd pinnate with 5 leaflets, the leaflets oblanceolate, 5–20 mm long with entire margins. The inflorescences are axillary, globose capitate or subcapitate racemes with 1-6 flowers. The 5-lobed cylindrical calyx tube is hairy, 6-15 mm long with teeth 1.5-4 mm in length. The corolla is papilionaceous, the white petals are clawed (narrowed at the base), the banner is slightly reflexed, 15–30 mm long, the wings 12-24 mm long and the keel is 10–22 mm long, often purple-tipped. The fruit is a legume, 6-10 mm long, oblong or ellipsoidal, exserted from calyx, beaked, hairy, and contains 3-10 mitt shaped seeds. Prairie milkvetch blooms in May and June on rocky prairie hilltops, slopes or barren flats in western South Dakota.

Additional Notes

Plains orophaca is a curious addition to a rock garden. If forms mounds when grown under moister conditions and provides unique textures to a garden.

Horticulture Notes

Seed Collection: Collect seeds when pods have turned brown and begin to split.

Germination: Seeds require cold treatment and scarification to help with water entry into the seed. Fall planting will usually provide good germination in the spring.

Light: Full sun.

Soil: Very adaptable to many soil types as long as they are well drained.

Water: Prefers dryer conditions.