Astragalus ripleyi
Leafl. W. Bot. 6: 175. 1952.
Plants robust, 40–70 cm, strigulose; from subterranean branched caudex. Stems erect or ascending, 2–10 cm underground, strigulose. Leaves 4–9(–11) cm; stipules distinct throughout, 1–5 mm, papery-scarious at proximal nodes, herbaceous at distal nodes; leaflets 11–21, blades linear or linear-elliptic to subfiliform, 8–30 mm, apex acute, obtuse, or truncate, surfaces strigulose abaxially, glabrate adaxially; terminal leaflet usually continuous with rachis. Peduncles arcuate-erect, (3.5–)6–12(–15) cm. Racemes (5–)15–45-flowered, flowers declined and secund; axis 2–16 cm in fruit; bracts 1–2 mm; bracteoles 0. Pedicels 2.3–7 mm. Flowers 13–17 mm; calyx purplish or whitish, cylindric, 5.5–7 mm, strigose, tube 5–6.6 mm, lobes triangular-subulate, 0.5–1.1 mm; corolla pale lemon yellow, concolorous; banner recurved through 35°; keel (9.5–)10–11.3 mm, apex bluntly or sharply deltate. Legumes pendulous, green or reddish becoming stramineous, straight or slightly curved, linear-oblong to lanceoloid or narrowly ellipsoid, strongly compressed, flattened laterally, (14–)20–33 × (3.5–)4–6 mm, papery, ± translucent in age, strigulose; stipe 8–15 mm. Seeds 11–17.
Phenology: Flowering Jun–Jul.
Habitat: Sagebrush, rabbitbrush, pinyon-juniper, ponderosa pine, Douglas-fir, Gambel oak, and aspen communities.
Elevation: 2100–2800 m.
Discussion
Astragalus ripleyi has a restricted range in Archuleta and Conejos counties in Colorado, and Rio Arriba and Taos counties in New Mexico.
The glabrous leaflets and the continuity of the terminal leaflet with the rachis on most leaves, in conjunction with the laterally compressed fruits and elongate fruiting pedicels, distinguish Astragalus ripleyi from A. schmolliae, its close ally. The smaller, lemon yellow petals and laterally flattened fruits distinguish A. ripleyi from the coarser, larger-flowered A. lonchocarpus.
Astragalus ripleyi is in the Center for Plant Conservation’s National Collection of Endangered Plants.
Selected References
None.