Astragalus palmeri

Plants perennial (sometimes flowering first year), (10–)15–50 cm, silvery-strigulose; from superficial root-crown. Stems prostrate or weakly ascending, silvery-strigulose. Leaves (2–)3–13(–16) cm; stipules distinct, (1.5–)2–6.5 mm, submembranous; leaflets (9 or)11–21, blades oblong, oblong-ovate or -obovate, or broadly to narrowly elliptic, (3–)5–25 mm, apex usually acute or obtuse and apiculate, rarely retuse-emarginate, surfaces sparsely strigulose abaxially, usually densely to sparsely strigulose adaxially, rarely glabrous or glabrescent. Peduncles ascending or incurved, 4–13 cm. Racemes (10–)20–40-flowered, flowers widely ascending or spreading; axis (3.5–)4–21 cm in fruit; bracts 0.8–2.6 mm; bracteoles 2. Pedicels 0.5–3(–3.4) mm. Flowers 7–10.3 mm; calyx campanulate or ovoid-campanulate, 3.6–6.6 mm, strigulose, tube (2.2–)2.7–3.8 mm, lobes subulate or triangular-subulate, (0.9–)1–2.8 mm; corolla bright pink-purple, or ochroleucous with purple tips or veins; banner recurved through 90°, 7–10.3 mm; keel 6.2–8.8 mm, apex round or narrowly triangular and beaklike. Legumes ascending, spreading, or declined, pale green or purple-specked or -suffused becoming stramineous, straight or slightly incurved, obliquely ovoid-ellipsoid or ovoid-acuminate, moderately to strongly bladdery-inflated, ± dorsiventrally or laterally compressed, 9–23 × (4–)5–15(–17) mm, beak prominent, papery, sparsely to densely strigulose. Seeds (7–)12–31.

Phenology: Flowering Dec–Jun.
Habitat: Open gravelly or sandy flats, hillsides, canyon benches and boulder-strewn slopes or washes, with pinyon pine, Joshua tree, scrub-oak or manzanita, sometimes on desert floor, on granitic bedrock.
Elevation: (100–)300–1300(–1700) m.

Ariz., Calif., Mexico (Baja California).

Discussion

Astragalus palmeri is restricted to the Colorado Desert region in California; though the type is reputed to have come from Arizona, the species has only been collected there once since. Plants of the northern portion of the range have larger fruits and a greener aspect; the more southern forms are silvery. Individual populations differ in a polymorphic manner, but variation is more or less continuous.

Selected References

None.

Lower Taxa