Astragalus sclerocarpus
Proc. Amer. Acad. Arts 6: 225. 1864.
Plants clump-forming, 20–50 cm, strigulose; from superficial or shallow subterranean caudex. Stems clustered, decumbent to ascending or straggling, often conspicuously flexuous, diffuse, strigulose. Leaves (3–)5–13 cm; stipules 1.5–5 mm, papery at proximal nodes, subherbaceous at distal nodes; leaflets (5 or)7–17, blades linear, linear-oblanceolate, or narrowly oblong, 3–23 mm, apex obtuse or retuse, surfaces strigulose or, sometimes, glabrescent or glabrous adaxially. Peduncles 4–9.5 cm. Racemes (3–)7–21-flowered; axis (1–)2.5–6.5 cm in fruit; bracts 1–2 mm; bracteoles 2. Pedicels 1–2.5 mm. Flowers 13–16.3 mm; calyx 5.9–8 mm, strigulose, hairs white, black, and brown, tube 5.3–7 mm, not swollen or gibbous proximally, marcescent, lobes triangular, 0.5–1.3 mm; corolla whitish, banner and wing tips tinged with lilac, keel maculate; keel 10–12.1 mm. Legumes pendulous, brown-stramineous, ± straight to sigmoidally incurved through 0.5 spiral, lunately or falcately ellipsoid, subterete becoming laterally compressed, 20–35 × (5.5–)6.5–9 mm, stiffly leathery or subligneous, strigulose; stipe 12–20 mm, arched downward from calyx, distally sigmoidal-incurved. Seeds 30–36.
Phenology: Flowering Apr–Jul.
Habitat: Dunes, sandy cutbacks, terraces, and barrens, with sagebrush.
Elevation: 60–500 m.
Distribution
B.C., Oreg., Wash.
Discussion
Astragalus sclerocarpus is known from the banks of the Columbia and lower Snake and Yakima rivers, from The Dalles upstream to Kettle Falls and northward through central and northeastern Washington to southern British Columbia.
The long-stipitate, scimitar-shaped, bicarinate fruits tapering at both ends are characteristic of this rather handsome, clump-forming, sparsely leafy xerophyte. The body tapers so gently into the stipe that it is sometimes difficult to differentiate the two.
A similar species, 356. Astragalus asotinensis, keys here. That species differs from A. sclerocarpus in having sparse pubescence, trichomes shorter than 0.5 mm, 15–23 oblong to narrowly oblong leaflets, and a pod 3–3.5 mm and incurved 70–110°.
Selected References
None.