Plants perennial (short-lived, often flowering first year), forming bushy clumps, some­what coarse, (7–)15–40 cm, strigulose; from superficial root-crown. Stems decumbent to ascending, strigulose. Leaves (2–)4–10(–11.5) cm; stipules distinct, (2–)3–8 mm, papery at proximal nodes, submembranous at distal nodes; leaf­lets (9–)13–21, blades oblong-elliptic, oblanceolate, or linear-elliptic, 5–15(–18) mm, apex obtuse, truncate and apiculate, or shallowly retuse, surfaces strigulose abaxially, glabrous adaxially. Peduncles erect or incurved-ascending, 0.3–0.9 cm. Racemes (7–)10–25(–32)-flowered, flowers spreading; axis (2–)3–7(–11) cm in fruit; bracts 1–2.4 mm. Pedicels 0.5–1.8 mm. Flowers 5.7–7.1 mm; calyx campanulate, 3.3–5 mm, strigulose, tube 2.2–2.9 mm, lobes subulate or lanceolate-subulate, (1–)1.3–2.3 mm; corolla reddish lilac or reddish purple; banner recurved through 50°; keel 4.7–5.6 mm, apex obtusely deltate, sometimes obscurely beaklike. Legumes spreading or declined, green or minutely purple-dotted becoming stramineous, straight or slightly incurved, broadly and plumply ovoid- or obovoid-ellipsoid, obovoid, or subglobose, bladdery-inflated, 6–13 × 6–10 mm, beak nearly obsolete, thin becoming papery, sparsely strigulose. Seeds 8–11. 2n = 22.

Phenology: Flowering Mar–May.
Habitat: Plains, valleys, open hillsides, on dry sandy or gravelly soils, on semistabilized dunes, with Larrea and Prosopis, oak brush and juniper, in mesquite-grasslands.
Elevation: 900–1900 m.

Distribution

• Generated Map
• Legacy Map

Loading map...

Ariz., N.Mex., Mexico (Sonora).

Discussion

With its compact, small, rounded, inflated fruits and small flowers, Astragalus thurberi is one of the more distinctive species of the large and difficult sect. Inflati. It contains swainsonine and is considered poisonous (L. F. James and S. L. Welsh 1992). It is a species of southeastern Arizona, southwestern New Mexico, and adjacent Mexico.

Selected References

None.

Lower Taxa

None.