Astragalus falcatus

Plants 40–90 cm, strigulose; from superficial or shallow, subterranean branched caudex. Stems ascending to erect, hollow but not fistulose, strigulose. Leaves 5–22 cm; stipules 2–12 mm, submembranous, pallid; leaflet blades oblong to elliptic or oblanceolate, 6–35 mm, apex acute to apiculate, surfaces strigose abaxially, glabrous adaxially. Peduncles ascending, 6–17 cm. Racemes 20–70-flowered, flowers recurved in fruit; axis 3–20 cm in fruit; bracts 2–5 mm; bracteoles 2. Pedicels 3.2–6.5 mm. Flowers 9–11(–12) mm; calyx 3.6–4.7 mm, strigose, tube 3–3.5 mm, lobes triangular, 0.5–1.2 mm; corolla keel 8–10 mm. Legumes stramineous, curved-oblong, 13–23 × 2.5–4.5 mm, thinly fleshy becoming stiffly papery, strigose. 2n = 16.

Phenology: Flowering Jun–Aug.
Habitat: Open grasslands, along streams, oak brush and mountain brush to aspen communities.
Elevation: 800–3300 m.

Introduced; B.C., Colo., Mont., Oreg., Utah, Wash., Asia.

Discussion

Astragalus falcatus was evidently first collected in North America in 1929, near Pullman, Washington. Later it was intentionally introduced as a plant that could occupy stressed environments in the American west that were subject to accelerated erosion. It was suspected of being poisonous to livestock (M. C. Williams and R. C. Barneby 1977) and is now known to contain nitrotoxins (L. F. James and S. L. Welsh 1992).

Selected References

None.

Lower Taxa