Astragalus agrestis

Plants clump-forming, slender, 9–43 cm, strigulose to villous-pilose, sometimes sparsely so; usually from subterranean branched caudex, rarely super­ficial, branches very long, rhizomatous. Stems diffuse or erect to decumbent-clambering, sparsely strigulose-pilosulous. Leaves 2–10 cm; stipules (1–)2–11 mm, papery-scarious proximally, submembra­nous at distal nodes; leaflets 13–23, blades narrowly elliptic to lanceolate-oblong, 4–18 mm, apex obtuse to retuse or acute, surfaces strigulose. Peduncles erect or incurved-ascending, 1.5–15 cm. Racemes 5–15-flowered, flowers ascending-erect; axis 0.5–2.5 cm in fruit; bracts 3–7 mm; bracteoles 0. Pedicels 0.5–1.5 mm. Flowers 17–24 mm; calyx cylindric, 7–12.5 mm, villous, tube 5–7.8 mm, lobes linear, 2.5–5.5 mm; corolla usually pink-purple, sometimes ochroleucous or nearly white; keel 11.4–14 mm. Legumes erect, green becoming dark, ± straight, oblong-ellipsoid, obtusely 3-sided, 7–10 × 2.8–4.5 mm, sulcate abaxially, scarcely swollen, thinly papery, densely silky-villous; stipe 0.3–1 mm. 2n = 16.

Phenology: Flowering May–early Sep.
Habitat: Meadows, prairies, hill­sides, stream banks, openings in sagebrush and aspen communities.
Elevation: 300–3300 m.

Distribution

• Generated Map
• Legacy Map

Loading map...

Alta., B.C., Man., N.W.T., Ont., Que., Sask., Yukon, Alaska, Calif., Colo., Idaho, Iowa, Minn., Mont., Nebr., Nev., N.Mex., N.Dak., Oreg., S.Dak., Utah, Wash., Wyo., Asia.

Discussion

Astragalus agrestis is commonly a sod-forming meso­phyte. Since the revision of A. Gray (1864), this species has been associated with A. laxmannii (as the name is applied here), but each belongs to a different phylo­genetically natural group, the centers of which are in central Asia and the Near East (R. C. Barneby 1964). The field milkvetch is taxonomically isolated in the American flora but is sufficiently similar to A. danicus Retz from eastern Europe to central Asia (where it over­laps with A. agrestis to some extent) that D. Isely (1998) suggested that A. agrestis is a regional associate of that species. There are indications that the two intergrade in the Altai region of southern Siberia (Barneby).

Astragalus dasyglottis Fischer ex de Candolle is an illegitimate name that applies here.

Selected References

None.

Lower Taxa

None.