Astragalus arrectus
Proc. Amer. Acad. Arts 8: 289. 1870.
Plants clump-forming, slender, 28–52 cm, strigulose, hairs basifixed; from superficial caudex. Stems erect to ascending, strigulose. Leaves (6–)9–22 cm; stipules 4–8 mm, membranous becoming papery-scarious; leaflets (17–)21–31, blades linear-oblong, narrowly oblong-elliptic, lanceolate, or oval, (3–)8–22 mm, apex obtuse or truncate-emarginate, surfaces strigulose abaxially, glabrous adaxially. Peduncles erect, 10–25(–30) cm. Racemes 15–30-flowered, flowers ascending; axis 8–22 cm in fruit; bracts 1.7–2.5 mm; bracteoles 2. Pedicels 0.5–4 mm, clavately thickened in fruit. Flowers 10–10.7 mm; calyx campanulate, 5–6.3 mm, strigulose-pilosulous, tube 3.7–4.7 mm, lobes lanceolate-subulate, (1.9–)2.2–5.2 mm; corolla ochroleucous, drying yellowish, immaculate; banner recurved through 45°; keel 10.1–10.6 mm. Legumes erect, brownish stramineous, straight or slightly incurved or decurved, narrowly oblong-ellipsoid, obcompressed, 15–23 × 4.5–6.3 mm, ± bilocular, ± fleshy becoming stiffly leathery, strigulose; septum 0.5–0.9 mm wide; stipe (2.5–)3–6 mm. Seeds 18–26. 2n = 24.
Phenology: Flowering mid Apr–Jul.
Habitat: Grassy hillsides, sagebrush slopes, ponderosa pine forests.
Elevation: 300–800 m.
Discussion
Astragalus arrectus is restricted to southeastern Washington and immediately adjacent Idaho. D. Isely (1998) presented a key to distinguish this from A. atropubescens and A. leibergii, which are similar in fruit.
Selected References
None.