Astragalus mulfordiae
Plants 10–30 cm, sparsely strigulose; caudex without thatch of persistent leaf bases. Stems spreading to ascending and diffuse, with well-developed internodes, sparsely strigulose. Leaves (2.5–)4.5–10.5 cm; stipules connate-sheathing at proximal nodes, distinct at distal nodes, 1.5–6 mm, papery-scarious; leaflets (7–)15–25, blades linear-oblong, -oblanceolate, or filiform, 1–11 mm, apex obtuse or subacute, surfaces strigulose abaxially, glabrous adaxially; terminal leaflet sometimes decurrent distally, not jointed to rachis. Peduncles (0.5–)1.5–7 cm. Racemes (5–)8–20-flowered; axis (2–)3–10 cm in fruit; bracts 0.7–2 mm; bracteoles 0–2. Pedicels 0.7–2 mm. Flowers 6–8.2 mm; calyx 2.5–5 mm, strigulose, tube (1.5–)1.8–3 mm, lobes subulate, 0.8–2 mm; corolla usually white or whitish, rarely yellow, drying yellowish, banner sometimes brownish-striate; banner abruptly recurved through (50–)85–100°; keel 4.7–5.7 mm. Legumes pendulous, stramineous, slightly incurved, lunately semi-ellipsoid, 3-sided compressed, 9–16 × 3–4.5 mm, papery, finely strigulose; septum 1.3–2 mm wide; stipe 3–5 mm. Seeds 11–16.
Phenology: Flowering May–Jun.
Habitat: Sandy bluffs and dunelike talus, foothills, with rabbitbrush, western wheatgrass, and bitterbrush.
Elevation: 600–900(–1000) m.
Distribution
Idaho, Oreg.
Discussion
Astragalus mulfordiae occurs near the Boise and Snake rivers and tributaries, near the western end of the Snake River Plains in Ada, Owyhee, and Washington counties in southwestern Idaho, and eastern Malheur County in Oregon.
Despite the distinct stipules and pubescence of Astragalus oniciformis, A. mulfordiae seems more appropriately aligned with that species. R. C. Barneby (1957) discounted any relationship of A. mulfordiae with the Old World, monospecific Onix Medikus and concluded that the similarity in fruits is to be attributed to convergence. He erected sect. Neonix to accommodate this attractive, small plant and its two presumed closest relatives.
Astragalus mulfordiae is in the Center for Plant Conservation’s National Collection of Endangered Plants.
Selected References
None.