Plants relatively robust, 10–35 cm, strigulose; from subter­ra­nean caudex. Stems erect, ascend­ing, or decumbent, 2–8 cm underground, strigulose. Leaves 1.5–8.5 cm; stipules 2–5.5 mm, herbaceous; leaflets 9–23, blades linear, narrowly oblong, or elliptic, 1–33 mm, apex obtuse to acute, surfaces strigose or glabrous; terminal leaflet sometimes decurrent distally, not jointed to rachis. Peduncles ascending, 1–6.5 cm. Racemes 6–15-flowered, flowers ascending; axis 1–4 cm in fruit; bracts 1.5–3.5 mm; bracteoles 0–2. Pedicels 1.4–4.3 mm. Flowers 15–19 mm; calyx cylindric, 5.5–8.7 mm, strigose, tube 4.7–7 mm, lobes subulate, 0.8–2.8 mm; corolla white to yellowish and tinged faintly with pink, sometimes lightly suffused with pink-purple on drying, keel tip faintly to darkly purple; keel 10.2–13 mm. Legumes pendulous, green or purple-mottled becoming stramineous or brownish, strongly incurved or coiled, obliquely oblong, sharply 4-sided compressed, 20–40 × 6–10 mm, fleshy becoming stiffly papery, glabrous or strigose. Seeds 28–38.

Phenology: Flowering Apr–Jul.
Habitat: Pinyon-juniper and sagebrush communities.
Elevation: 1000–2200 m.

Distribution

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Ariz., Idaho, Nev., Oreg., Utah.

Discussion

Astragalus tetrapterus contains nitrotoxins that are poisonous to livestock (L. F. James and S. L. Welsh 1992), but it is seldom sufficiently abundant as to result in large-scale loss. The fresh fruit is fleshy, with the dor­sal suture essentially flat and the ventral suture raised in a low ridge; it becomes four-winged upon drying.

Astragalus cinerascens (Rydberg) Tidestrom is an illegitimate name that pertains here.

Selected References

None.

Lower Taxa

None.