Astragalus laxmannii var. robustior
Great Basin Naturalist 56: 85. 1996.
Leaves 4–17 cm; leaflets (9 or)11–25, blades (4–)8–27(–33) mm. Peduncles (3–)4–14(–16.5) cm. Racemes (7–)16–50-flowered; axis (0.6–)1.5–9(–13) cm in fruit. Flowers 13–19.5 × 4–7(–8) mm; calyx 5.8–10.5 mm, tube (4–)4.4–7 × (2–)2.3–3.2 mm, lobes subulate or subulate-setaceous, 1.4–4.2 mm; corolla magenta-purple, reddish lilac, dull blue, pale milky white. Legumes narrowly ovoid-, oblong-, or lanceoloid-ellipsoid, 7–12 × 2.3–3.8 mm, densely strigulose, hairs short and sinuous mixed with longer and straight ones, white or mixed with black; stipes 0–0.5 mm. Seeds 9–14(–16). 2n = 32.
Phenology: Flowering May–Aug.
Habitat: Plains, prairies, dry hillsides, on bare, rocky or gravelly areas on gravelly or shingly lakeshores or riverbanks, on sedimentary bedrock.
Elevation: 200–2000(–3400) m.
Distribution
Alta., B.C., Man., N.W.T., Ont., Sask., Yukon, Colo., Idaho, Iowa, Minn., Mont., Nebr., N.Mex., N.Dak., S.Dak., Utah, Wash., Wyo.
Discussion
R. C. Barneby (1964) reviewed, partly in tabular form, the extensive synonymy associated with the widespread var. robustior. Some of the variants may ultimately be found to be worthy of taxonomic recognition.
Selected References
None.