Astragalus aridus

Plants annual (short-lived, of 2–4 months duration), slender or coarse, 2.5–30 cm, densely strigulose-pilose; from super­ficial root-crown; taproot slender. Stems single or few, decumbent with ascending tips or trailing and diffuse, densely white-strigulose-pilose. Leaves (2–)3–9(–10) cm; stipules distinct, 1.5–5(–6.5) mm, herbaceous becoming papery; leaflets (7 or)9–17, blades oblanceolate, oblong-oblanceolate, or elliptic, 4–16 mm, apex obtuse, truncate, or emarginate, surfaces pubes­cent. Peduncles incurved-ascending, 2–5.5 cm. Racemes (3 or)4–9-flowered, flowers ascending; axis 1.5–5.5 cm in fruit; bracts 0.8–2.2 mm; bracteoles 0. Pedicels 0.2–1 mm. Flowers (3.3–)3.5–6.5 mm; calyx turbinate-campanulate, 3.3–4.3 mm, densely silvery-pilose, tube 2.1–2.7 mm, lobes broadly subulate, 1–1.6 mm; corolla whitish, faintly tinged with pink-lilac or cream-pink; banner recurved through 40°; keel 3.6–5 mm, apex round or narrowly triangular and beaklike. Legumes ascending, incurved, semi-ellipsoid or lunately ellipsoid, slightly inflated, scarcely bladdery, 10–17 × 4.5–7 mm, thin becoming papery, opaque, canescently strigulose-pilosulous. Seeds (3 or)4–6(or 7).

Phenology: Flowering Feb–May.
Habitat: Desert dunes, open sandy plains, valley floors.
Elevation: -60–400 m.

Distribution

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

Discussion

Astragalus aridus is a species of the Colorado Desert in southern California and adjacent Arizona. It is vaguely similar to A. insularis, but the flowers of A. aridus are smaller than those of any similar species.

Selected References

None.

Lower Taxa

None.