Plants 20–40 cm, strigulose; from shallow subterranean cau­dex. Stems incurved-ascending, diffuse, 1–12 cm underground, strigulose. Leaves (3.5–)5–10 cm; stipules connate-sheathing at proximal nodes, distinct or shortly or obscurely connate distally, 2–7 mm, papery prox­imally, herbaceous distally; leaflets 11–25, blades oblong-elliptic or obovate, (2.5-)5–14 mm, apex emarginate, surfaces strigulose abaxially, sparsely hairy or glabrous adaxially. Peduncles 4.5–8 cm. Racemes 8–20-flowered, flowers spreading, later declined; axis 2–5 cm in fruit; bracts 2–4 mm; bracteoles 0. Pedicels 0.8–3.5 mm. Flowers 14–18.7 mm; calyx subcylindric, 7.9–10 mm, strigulose or villosulous, tube 5.8–7.2 mm, lobes subulate, 2–3.5 mm; corolla pale purple (drying dull lavender); banner recurved through 45°; keel 11–14.4 mm. Legumes humistrate, spreading, or declined, often red-mottled, subsymmetric, ovoid-acuminate or ovoid-ellipsoid, subterete, bladdery-inflated, 22–28 × 11–16 mm, papery-membranous, translucent, loosely strigulose to villosulous; stipe 1.5–3 mm. Seeds 22–26. 2n = 22.

Phenology: Flowering Apr–May.
Habitat: Dry, rocky slopes in pinyon forests, open juniper woodlands.
Elevation: 1500–1700 m.

Distribution

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N.Mex.

Discussion

Astragalus castetteri occurs in the Caballo and San Andres mountains of south-central New Mexico in Doña Ana and Sierra counties.

Astragalus castetteri is the only species in the group with thinly membranous inflated fruits, probably derived from A. hallii var. fallax (R. C. Barneby 1964). Barneby also noted that A. castetteri reverted to vernal flowering; recent collections indicate that about 20% of collections were from autumn-blooming plants.

Selected References

None.

Lower Taxa

None.