Astragalus filipes

Plants large clump-forming, 20–90 cm, glabrate to densely strigulose; from superficial cau­dex. Stems erect or ascending, glabrate to densely strigulose. Leaves 2.5–12 cm; stipules connate-sheathing and papery-membranous at prox­imal nodes, distinct and herbaceous at distal nodes, 2–5 mm; leaflets (5–)9–23, blades linear to narrowly ellip­tic or oblong, 3–25(–30) mm, apex obtuse to truncate, retuse, or subacute, surfaces usually glabrous, sometimes strigose. Peduncles erect or ascending, 4.5–22 cm. Racemes (4–)6–30-flowered, 1 per leaf axil; axis 4–22 cm in fruit; bracts 1–3.5 mm; bracteoles 0. Pedicels 1.5–6 mm. Flowers 10–14.3(–15) mm; calyx subcylindric to campanulate, 4–7.7 mm, strigulose, hairs black and white, tube 3.3–6.4 × 2.4–3.5(–4.4) mm, lobes triangular, 0.5–1.5 mm; corolla whitish to ochroleucous, keel immaculate or bright yellow; banner recurved through 50–85°; keel abruptly incurved through 95–120°, blades about as long as claws, (6.7–)7.6–10(–12) mm, apex deltate or triangular. Legumes pale green, not mottled, not stramineous, straight, oblong to ellipsoid, strongly laterally compressed, 17–30(–35) × (3–)3.5–6.5 mm, papery, glabrous or strigulose; stipe 6–16 mm. Seeds 11–22. 2n = 22, 24.

Phenology: Flowering May–Jul.
Habitat: On sandy, loamy, or gravelly soils derived from igneous or sedimentary (often limestone) bedrock, with various plant communities, mostly with sagebrush.
Elevation: 70–2500 m.

Distribution

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B.C., Calif., Idaho, Nev., Oreg., Utah, Wash., Mexico (Baja California).

Discussion

Astragalus filipes is often so dense as to color hill­sides with a wash of creamy, fragrant blossoms; it is unmistakable throughout most of its range. Except in northeastern California, where its range overlaps those of two closely related species, A. californicus and A. inversus, A. filipes is the only Astragalus combining connate stipules with stipitate, laterally compressed, unilocular fruits (except for A. multiflorus, with much smaller flowers and fruits).

Astragalus stenophyllus Torrey & A. Gray 1838 was historically used for A. filipes, but its type specimen lacks the features necessary for species-level identification (R. C. Barneby 1964).

Selected References

None.

Lower Taxa

None.