Astragalus reventiformis
Amer. Midl. Naturalist 55: 492. 1956.
Plants robust, stout, caulescent to subacaulescent, 15–45 cm, strigulose-pilose. Stems erect or ascending, distalmost internode longer than others combined, strigulose-pilose. Leaves (6.5–)8–22(–30) cm; stipules connate-sheathing at proximal nodes, mostly connate at distal nodes, 2.5–7 mm, papery-membranous; leaflets (13–)17–27(–33), blades linear-oblong, lanceolate, lanceolate-elliptic, or oval-oblong, 4–21(–25) mm, apex obtuse, truncate-emarginate, apiculate, or acute, surfaces strigulose-pilose abaxially, usually glabrous or glabrescent adaxially. Peduncles stiffly erect, (7–)10–30 cm, together with racemes longer than stems. Racemes (7–)10–19-flowered, flowers ascending initially; axis (2.5–)4–12 cm in fruit; bracts 1.5–4.5(–6) mm; bracteoles 2. Pedicels 2.7–6 mm. Flowers (13.2–)14–20.7 mm; calyx campanulate, (7.8–)8–12.2 mm, pilosulous, tube (4.7–)5.3–7.5 mm, lobes lanceolate-subulate, (2.4–)2.7–5.1 mm; corolla white or whitish, drying yellowish, immaculate or keel tip purplish; banner recurved through 90°, oblong-oblanceolate, rhombic-oblanceolate, elliptic, oblong-ovate, or somewhat quadrately ovate-cuneate, (13.2–)14–20.7 mm, apex usually deeply notched; keel 10–13(–13.7) mm. Legumes brownish, straight or slightly incurved, ovoid-acuminate to oblong-ellipsoid, somewhat obcompressed, (10–)15–22 × (5–)6–11 mm, sub-bilocular, thick and fleshy becoming stiffly leathery or woody, glabrous; septum 0.6–2 mm wide; sessile. Seeds (20–)22–35.
Phenology: Flowering late Apr–Jun.
Habitat: With sagebrush on basalt bedrock or alluvium.
Elevation: 300–1600 m.
Discussion
Astragalus reventiformis and its immediate relatives have connate stipules and erect, persistent, leathery fruits. They form a pattern of geographic replacement mostly east of the Cascade Range: A. conjunctus, with a cylindric calyx tube, is from south-central Washington, north-central and eastern Oregon, and southwestern Idaho; A. hoodianus, from low elevations along the Columbia River in north-central Oregon and adjacent Washington, has long, commonly divergent calyx lobes; A. reventiformis lies to the north in Washington, immediately southward of A. leibergii, which has shortly stipitate fruits (D. Isely 1998).
Selected References
None.