Astragalus robbinsii var. occidentalis
Botany (Fortieth Parallel), 70. 1871.
Stems usually ascending, (10–)15–45 cm. Leaves 4–9.5 cm; proximal stipules connate 1/2 their length; leaflets (5 or)7–11, blades 8–30 mm, surfaces strigulose abaxially, hairs subappressed, to 0.2–0.5 mm. Peduncles (6–)8–21 cm. Racemes remotely (3–)6–12-flowered; axis (2–)6–15 cm in fruit. Flowers 7.5 mm; corolla lilac. Legumes flattened or obscurely depressed abaxially, (8–)10–15(–18) × (3–)4–5 mm, apex 0.8–1.2 mm, strigulose; septum 0.8–1.2 mm wide; stipe 0.5–1.4 mm. Seeds 8.
Phenology: Flowering Jul–Aug.
Habitat: Banks of streams, moist soils of timbered creek beds.
Elevation: 1800–3100 m.
Discussion
No single character distinguishes var. occidentalis from var. minor. In combination, the very slender growth-habit, few but ample leaflets, remotely few-flowered racemes, and usually small, short-stipitate or subsessile fruits distinguish the taxon. Variety occidentalis is a narrow endemic to the Humboldt and Ruby mountains of Elko County.
Selected References
None.