Astragalus simplicifolius
Proc. Amer. Acad. Arts 6: 231. 1864.
Plants tuft- or mat-forming, 10–35 cm, densely strigulose; from branched caudex. Stems obscured by marcescent leaf bases and stipules. Leaves reduced to phyllodia, 0.4–2.5 cm; stipules connate-sheathing, 3–6 mm, membranous; phyllodia oblanceolate or spatulate, 4–25 mm, apex acute or apiculate, surfaces strigose. Peduncles erect or ascending, (0.5–)1–3 cm. Racemes 1–4-flowered; axis 0–0.5 cm in fruit; bracts 0.4–1.8 mm. Pedicels 0.5–1.8 mm. Flowers 10.6–12 mm; calyx 4.5–7 mm, prominently veined in fruit, strigose, tube 3–4.1 mm, lobes broadly subulate, 1.3–3 mm; corolla pink-purple; banner recurved through 45°; keel 7–9.6 mm. Legumes ascending, green or red-mottled becoming stramineous or brown, slightly curved, narrowly ovoid-ellipsoid to lanceoloid-ellipsoid, laterally compressed, 6–13(–15) × 2–5 mm, papery, glabrous or glabrate; sessile. Seeds 11–14.
Phenology: Flowering May–Aug.
Habitat: Hilltops, barren ridges, on gullied bluffs, on shale or sandstone, on limestone pavement.
Elevation: 1600–2300 m.
Discussion
Astragalus simplicifolius, restricted to valleys of the upper Platte and Wind rivers, is completely included within the range of A. spatulatus, from which it is distinguished by its relatively larger flowers and laterally ridged fruits.
Selected References
None.