Astragalus platytropis

Plants closely tuft-forming, acaulescent or subacaulescent, 2–7 cm, strigulose; from branched, superficial caudex, branches often with thatch of persistent leaf bases. Stems mostly reduced to crowns, prostrate-ascending or erect, 0–2 cm, (0–)1–3 cm underground, often with thatch of marcescent leaf bases, strigulose. Leaves 1–7 cm; stipules usually connate at proximal nodes, distinct at distal nodes, 1.5–5 mm, subherbaceous becoming papery; leaflets 5–15, blades elliptic to obovate, oblong, or oval, 2–11 mm, apex acute to obtuse or retuse, surfaces silvery-strigose. Peduncles ascending, 1.5–6.5 cm. Racemes 2–9-flowered, flowers ascending; axis 0.2–0.6 cm in fruit; bracts 0.6–2 mm; bracteoles 0–2. Pedicels 0.7–1.9 mm. Flowers 7–9.5 mm; calyx 3–5.4 mm, strigose, tube 2–3.4 mm, lobes subulate, 0.2–2.1 mm; corolla pink-purple; keel 7.8–8.6 mm. Legumes ascending, purple-mottled, straight, ovoid to subglobose, bladdery-inflated, 15–33 × 10–22 mm, bilocular or semibilocular, thin becoming papery, strigulose. Seeds 26–34.

Phenology: Flowering Jul–Aug.
Habitat: Ridge tops and scree in shrub and forest communities.
Elevation: 2400–3500 m.

Calif., Idaho, Mont., Nev., Oreg., Utah, Wyo.

Discussion

The easily recognizable Astragalus platytropis is marked by its tufted, silvery-gray foliage and subcapitate racemes of small, purplish corollas with petals of nearly equal length. It is found in scattered populations from east of the Sierra Nevada in Califoirnia eastward through Nevada to far western Utah, and northward to Malheur County, Oregon, north-central Idaho, and west-central Montana, with an isolated population in north-central Wyoming.

Selected References

None.

Lower Taxa