Astragalus duchesnensis
Plants rushlike, 15–40(–45) cm, strigulose; from subterranean caudex or rhizomes. Stems straggling to ascending or erect, mostly branched near base, 1.5–8+ cm underground, strigulose. Leaves 2–10 cm; stipules distinct throughout, 3–8 mm, papery-membranous at proximal nodes, firm at distal nodes; leaflets 5–15, blades linear, oblong, or narrowly oblanceolate, 3–20 mm, apex obtuse to retuse, surfaces strigose or, sometimes, glabrate adaxially; terminal leaflet decurrent distally, not jointed to rachis. Peduncles erect or incurved-ascending, 3–10.5 cm. Racemes 5–22-flowered, flowers ascending, finally nodding; axis 2.5–13 cm in fruit; bracts 0.7–2 mm; bracteoles 0. Pedicels 0.8–2.2 mm. Flowers 8.5–12.5 mm; calyx usually dull purple, campanulate, 3.5–5.5 mm, strigulose, tube 3–4.3 mm, lobes triangular, 0.4–1.5 mm; corolla pink-purple, wing tips white; banner recurved through 90–95°; keel 8–9.8 mm, apex obtuse to subacute, not beaklike. Legumes declined, pale green or purplish becoming stramineous, straight or gently decurved, oblong to narrowly oblanceoloid, dorsiventrally compressed in proximal 1/2, laterally compressed distally, 20–35 × 3.3–6 mm, stiffly papery, strigose; sessile. Seeds 21–31.
Phenology: Flowering Apr–Jun.
Habitat: Sandy or gravelly to fine-textured clay soils, in mixed desert shrub and pinyon-juniper communities.
Elevation: 1400–2000 m.
Discussion
Astragalus duchesnensis, a sparsely foliose plant, is known from northeastern Utah and adjacent Colorado and is locally common on the floor of the Uinta Basin. It is unusual among xerophytic astragali in being rhizomatous. Plants occur in colonies and, in favorable years, form bold clumps; in dry years the same colony may produce only a few straggling stems, sterile or nearly so.
Selected References
None.