Plants robust, 30–80 cm, strigu­lose; from shallow, subterra­nean caudex. Stems erect or ascending, 0.5–2.2 cm under­ground, strigulose. Leaves (6–)8–14(–18) cm; stipules distinct throughout, 3–12 mm, white-papery at proximal nodes; leaflets 7–15, blades linear, 10–43 mm, apex acute, surfaces strigulose; terminal leaflet jointed to rachis. Peduncles 8–15 cm. Racemes 10–25(–30)-flowered, flowers becoming twisted through 180°; axis 7–12 cm in fruit; bracts 1.5–2 mm; bracteoles 1 or 2. Pedicels 1–5 mm. Flowers (12–)14–18 mm; calyx campanulate, (4–)7–9 mm, strigose, tube 3.5–7 mm, lobes lanceolate-subulate, (0.5–)1.2–2.5 mm; corolla lemon yellow, concolorous; banner recurved through 80–110°; keel apex bluntly or sharply deltate. Legumes inverted from flexion of pedicels, ascending to erect, green becoming maroon-mottled, oblong-ellipsoid, moderately laterally compressed, 22–30 × 6–9 mm, glabrous; stipe 12–16(–19) mm. Seeds 17–27.

Phenology: Flowering Apr–Jun.
Habitat: Mixed salt desert shrub (shad­scale, rabbitbrush, and Eriogonum) communities, on Cretaceous Mancos Shale knolls and ridges with pedi­mental gravel.
Elevation: 1700–1800 m.

Distribution

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Colo.

Discussion

Astragalus tortipes is the most unusual member of sect. Lonchocarpi, known only from the vicinity of Towaoc, Montezuma County; the plants grow on Mancos shale with another rare species, A. cronquistii.

Astragalus tortipes is in the Center for Plant Conservation’s National Collection of Endangered Plants.

Selected References

None.

Lower Taxa

None.