Astragalus microcystis
Proc. Amer. Acad. Arts 6: 220. 1864.
Plants slender, 5–40(–50) cm, densely gray-villosulous; from superficial branched, suffruticose caudex. Stems decumbent and ascending, strigulose. Leaves 1.5–6.5 cm; stipules connate-sheathing and papery at proximal nodes, connate or distinct and herbaceous at distal nodes, 1–5(–6) mm, often drying blackish; leaflets 9–15, blades narrowly to broadly elliptic to oblong, oblanceolate, or obovate-cuneate, 3–14(–18) mm, apex acute to obtuse, surfaces strigose abaxially, strigose or glabrous adaxially. Peduncles 1–3 per leaf axil, 1.5–6.5(–8.5) cm. Racemes 4–20-flowered, flowers declined; axis 1.5–4.5(–6) cm in fruit; bracts 1–2.5 mm; bracteoles 0. Pedicels 0.7–2.5 mm. Flowers 5.1–7.8(–8.3) mm; calyx 2.7–3.8(–4.3) mm, strigulose-pilosulous, tube 1.5–2.2 mm, lobes subulate, 1–2(–2.3) mm; corolla pink-purple, or whitish and purple-veined or -tipped, wing tips often pale or white; banner recurved through 90°; keel 3.7–4.8 mm. Legumes spreading or declined, brown or stramineous, straight, plumply ellipsoid, obovoid-ellipsoid, or subglobose, bladdery-inflated, 5–12(–14) × 4–7 mm, slightly fleshy becoming papery-membranous, densely pilosulous; sessile. Seeds 6–8(or 9).
Phenology: Flowering Apr–Aug.
Habitat: Rocky scree slopes, grassy slopes, lakeshores, gravelly flats and bars.
Elevation: 300–1900 m.
Distribution
B.C., Idaho, Mont., Wash.
Discussion
Astragalus microcystis is known along the Columbia River and tributaries near the mouth of the Spokane River, from northeastern Washington and adjacent British Columbia, eastward to west-central Montana, and is disjunct on Mt. Tyler in Clallam County, Washington.
At least partially developed fruits are required to distinguish Astragalus microcystis from A. vexilliflexus. With flowering material only, distinction is difficult or impossible, leading to confusion regarding the geographic ranges of the species. Both species are partially sympatric; A. microcystis is the more western in Montana.
Selected References
None.