Astragalus yoderwilliamsii
Brittonia 32: 30, fig. 1. 1980.
Plants densely tuft-forming, diminutive, 1–3(–7) cm, sparsely strigulose; short caudex with thatch of persistent leaf bases. Stems erect or ascending, sparsely strigulose. Leaves 2.5–5.5 cm; stipules connate-sheathing and papery-membranous at proximal nodes, 1–2 mm; leaflets (7 or)9–17(or 19), blades obovate or narrowly elliptic, 1–3 mm, apex obtuse, surfaces sparsely strigulose; terminal leaflet smallest, jointed or continuous with rachis. Peduncles erect, 0–0.5 cm. Racemes 2–8-flowered; axis 1–3.5 cm in fruit. Flowers 5–7 mm; calyx 2.3–3.3 mm, strigulose, tube 1.5–2 mm, lobes subulate to triangular, 0.5–1 mm; corolla whitish, faintly veined pink; banner abruptly recurved; keel 4–4.5 mm. Legumes persistent, pendulous, stramineous, incurved, ellipsoid, sharply 3-sided compressed, 4–7 × 2–3 mm, thin becoming papery; valves inflexed, septum 1–2 mm wide; stipe 1–3 mm. Seeds 6–8.
Phenology: Flowering Jun–Jul.
Habitat: Sagebrush-rabbitbrush communities, on decomposed granitic gravel.
Elevation: 1500–2200 m.
Discussion
Astragalus yoderwilliamsii, once thought to be restricted to the northern Osgood Mountains in Humboldt County, Nevada, precipitated the first emergency ruling under the Endangered Species Act because the species occurs within a region of mining activity. It is now also known from Elko County, Nevada, and Owyhee County, Idaho.
Selected References
None.