Astragalus humistratus var. crispulus
Leafl. W. Bot. 4: 53, figs. 24–26. 1944.
Plants gray-villous, often also subtomentose, hairs extremely fine, weak, sinuous or curly, herbage cinereous. Stems (5–)15–55 cm. Stipules 2.5–8 mm. Leaves 1–4.5(–5) cm; leaflets 11–15, blades (2–)3–14 mm, surfaces pubescent adaxially. Peduncles (1–)1.5–3.5(–4) cm. Racemes (3–)5–12-flowered; axis (0.5–)1–3 cm in fruit. Flowers: calyx 4.6–5.5 mm, tube 2.9–4 mm, lobes subulate, 1.2–2.4 mm; corolla whitish, faintly tinged with pink; banner 7–9.2 × (3–)4–5 mm. Legumes lunately semi-ellipsoid, incurved, 8–10 × 2.5–3 mm, villosulous. Seeds 6–9.
Phenology: Flowering Aug–Sep.
Habitat: Xeric pine forests, on sandy soils of volcanic origin on slopes, benches, ledges.
Elevation: 2100–2500 m.
Discussion
Variety crispulus, endemic to the White Mountains of southeastern Arizona and the San Francisco Mountains of adjacent New Mexico, is sometimes sympatric with var. humistratus, and the two are remarkably different in appearance. The link between them is var. humivagans, which extends eastward into their range, but generally, and perhaps exclusively, at lower elevations.
Selected References
None.