Astragalus asotinensis
Novon 16: 299, fig. 1. 2006.
Plants perennial, sparsely strigose, hairs basifixed. Stems decumbent to ascending, sparsely strigose. Leaves 5–8 cm; stipules distinct throughout, 1.7–3.3 mm; leaflets 15–23, blades obovate-cuneate or oblong-oblanceolate, 7–16 mm, apex mostly truncate-retuse to obtuse, surfaces sparsely pubescent abaxially, nearly glabrous adaxially. Peduncles 6–10 cm. Racemes 7–20-flowered, flowers ascending at anthesis; axis 1.5–4.5 cm in fruit; bracts 1.4–2.7 mm; bracteoles usually 2. Pedicels 2 mm. Flowers 14–19 mm; calyx campanulate to subcylindric, 7.5–8.8 mm, tube 6–7.3 mm, teeth 1.5 mm, acuminate; corolla creamy-white, often tinged rose or lavender, especially on keel tip; banner recurved through 40–50°. Legumes spreading or pendulous, falcately oblong, laterally compressed, 28–37 × 3–3.5 mm, bicarinate, unilocular, sparsely white-strigose; stipe 6–9 mm. Seeds unknown.
Phenology: Flowering late Apr–early May.
Habitat: Dry limestone hillsides, among bunchgrasses and xeric shrubs.
Elevation: 400–900 m.
Distribution
Idaho, Wash.
Discussion
Astragalus asotinensis is restricted to Lime Hill at the northern extreme of Hells Canyon, divided by the Snake River, in Nez Perce County, Idaho, and Asotin County, Washington. It will key to 63. A. sclerocarpus, from which it differs in having sparse pubescence, trichomes shorter than 0.5 mm, 15–23 oblong to narrowly oblong leaflets, and a pod that is 3–3.5 mm and incurved 70–110°. It is also similar to A. sinuatus, from which it differs by its straight, appressed calyx pubescence and oblong to narrowly oblong leaflets.
Selected References
None.