Astragalus sabulonum

Plants annual, winter-annual, or biennial, coarse, 4–35 cm, villous-hirsutulous; from root-crown. Stems single or few, usually decumbent to ascending, rarely erect, villous-hirsutulous. Leaves 1.5–7 cm; stipules distinct, 1–4 mm, subherbaceous becoming papery; leaflets (5–)9–15, blades oblanceolate to oblong or obovate, 2–13 mm, apex retuse to truncate or obtuse, surfaces loosely villous, sometimes glabrate adaxially. Peduncles incurved-ascending, 0.5–4 cm. Racemes 2–7-flowered, flowers ascending-spreading; axis 0.3–2.5 cm in fruit; bracts 1–2.5 mm; bracteoles 0. Pedicels 0.8–2 mm. Flowers 5.2–8 mm; calyx campanulate, 3.3–6.2 mm, hirsutulous, tube 1.8–2.5 mm, lobes subulate, 1.8–3.5 mm; corolla usually pink-purple, rarely ochroleucous and tinged with purple; banner recurved 50–70°; keel (5–)5.4–6.5 mm, apex narrowly triangular, sometimes slightly beaklike. Legumes spreading-declined, green or purple-cheeked or -dotted, becoming brownish or stramineous, lunately incurved or hooked, obliquely ovoid, turgid or somewhat inflated, 9–17(–20) × (4–)5–8(–11) mm, thinly fleshy becoming leathery or stiffly papery, white-villous or hirsute, hairs spreading, curved, 0.7–2.2 mm. Seeds 10–19. 2n = 24.

Phenology: Flowering Nov–Jul.
Habitat: Larrea and other warm-desert shrub, mixed cool desert shrub, salt-desert shrub, and lower pinyon-juniper communities, on sandy substrates.
Elevation: (60–)500–2200 m.

Ariz., Calif., Nev., N.Mex., Utah, Mexico (Baja California, Sonora).

Discussion

Astragalus sabulonum is known from San Juan County in northwestern New Mexico, northern Arizona, north to Emery County in east-central Utah and Mineral County in southwestern Nevada, and southward through southeastern California to Baja California and Sonora in northern Mexico.

Although Astragalus sabulonum has a wide ecological amplitude, from warm-desert shrubland to pinyon-juniper woodland, it is reasonably uniform morphologically. It can be distinguished from its closest relatives, A. pubentissimus and A. pardalinus, by characteristics of the calyx (size), ovules (number) and fruit (size, pubescence, texture, and curvature) (D. Isely 1998).

Selected References

None.

Lower Taxa