Herbs, annual, usually mat-forming, sometimes cespitose (ascending and bushy), green to grayish, 0.3–5 dm, not or ± fleshy, strigillose, hirsute, canescent-tomentose, or scantily pubescent; taprooted. Stems 1–20+, procumbent or decumbent to ascending, branched basally, herbaceous, slender, leafy. Leaves irregularly pinnate; stipules glandlike; subsessile; rachis 3–20 mm, flattened; leaflets 4–10, blades unequal, obovate to oblanceolate to linear-oblong or oblong, apex acute to obtuse or truncate, surfaces ± densely tomentose to glabrate. Peduncles ascending or reflexed, upturned, 3–25 mm, shorter to longer than leaves (often elongated in fruit); bract absent or 1–3-foliolate, usually subtending umbel. Inflorescences 1–3-flowered. Flowers (5–)6–10(–12) mm; calyx 3–5.5 mm, tube ± sparsely strigillose or glabrous, lobes subulate; corolla yellow (sometimes banner orangish abaxially), turning orange or reddish, claws ± equaling calyx tube, banner implicate-ascending or remaining closely implicate, wings longer than keel; style corneously thickened, marked by color, straight, puberulent or glabrous. Legumes persistent, exserted, erect or divergent, brown, straight to ± curved distally, compressed, not or slightly constricted, incompletely septate, linear-oblong, 10–35 × 2–3 mm, thinly leathery, apex initially short-beaked, dehiscent, smooth, margins smooth, thin, glabrous or ± strigose. Seeds 5–10, greenish to brown, ± mottled, ovoid to cuboid or globose, rugulose or granular.

Distribution

sw United States, n Mexico.

Discussion

Varieties 3 (3 in the flora).

D. Isely (1981) discussed the variation in Acmispon strigosus (as Lotus), distinguishing three varieties, two rather distinct but with intergrading phases, and one apparently more transitional, although distinct enough to be recognized. These varieties were only noted for California in recent treatments (for example, L. Brouillet 2012, following D. Isely 1993). Nonetheless, the typical (for example, excluding intergrading phases) varieties represent recognizable morphologies that also have geographic distinction. Specimens representing inter­gradation seem to occur throughout the range of overlap of these varieties, sometimes rendering determination difficult.

Selected References

None.

Lower Taxa

Acmispon strigosus var. hirtellus, Acmispon strigosus var. strigosus, Acmispon strigosus var. tomentellus

Key

1	Herbs evidently hirsute, especially at apex, greenish.	Acmispon strigosus var. hirtellus
1	Herbs usually strigillose or canescent-tomentose to scantly pubescent, rarely strigillose, green or cinereous.	> 2
2	Stems ascending or decumbent, not markedly succulent, usually appearing green, sometimes cinereous; leaflet blades linear-oblong, apices acute to obtuse; corolla opening; California.	Acmispon strigosus var. strigosus
2	Stems prostrate, succulent, cinereous(–greenish); leaflet blades oblong, apices obtuse or truncate; corolla not opening; Arizona, California, Nevada.	Acmispon strigosus var. tomentellus