Plants slender, (10–)15–45 cm, strigulose; from superficial cau­dex. Stems prostrate to decum­bent or ascending, strigulose. Leaves 4–12 cm; stipules 2–8 mm, subherbaceous or papery; leaflets (9 or)11–21(or 23), blades linear-oblong to nar­rowly elliptic, (3–)5–20(–24) mm, apex acute to obtuse, surfaces strigulose abaxially, gla­brous or glabrate adaxially. Peduncles erect or incurved-ascending, (2–)5–12 cm. Racemes (10–)15–50-flowered; axis (1.5–)3–8 cm in fruit; bracts 1–3 mm; bracteoles 0–2. Pedicels 0.3–1.2 mm. Flowers 4.2–6.2 mm; calyx 2.5–3.6 mm, strigulose, tube 1.7–2 mm, lobes subulate, 0.8–1.8 mm; corolla yellow to green, suffused pale lavender, fading ochroleucous, wing tips pale or white; banner recurved through 45–90°; keel 3.7–5 mm, apex round. Legumes stramineous, narrowly lanceoloid or linear-ellipsoid, 6–12 × 1.3–2 mm, biloc­ular or sub-bilocular, thin becoming papery, strigulose. Seeds 6–10. 2n = 28.

Phenology: Flowering (Apr–)Jun–Oct.
Habitat: Oak-pine forests, along drainages, flats, foothills.
Elevation: 1200–2300 m.

Distribution

• Generated Map
• Legacy Map

N.Mex., Mexico (Chihuahua, Coahuila, Sonora).

Discussion

Astragalus vaccarum is a northern member of the primarily Mexican sect. Micranthi, long known from only a few old collections from southeastern Arizona and southwestern New Mexico. Thought extirpated in the United States, it was rediscovered in Hidalgo County, New Mexico, in the 1980s. Astragalus vaccarum is fairly common in northern Mexico.

Selected References

None.

Lower Taxa

None.