Herbs, perennial, or subshrubs, cespitose and ± prostrate, or shrubby and spreading to ascending, low or robust, sil­very or gray, 1–6(–10+) dm, not fleshy, tomentose to canescent or strigose; from woody caudices. Stems 1–20+, prostrate or decumbent to ascending, branched, herbaceous, slender, or ± woody, leafy, sometimes congested at tips. Leaves irregularly pinnate to sub­palmate; stipules glandlike; short-petiolate; rachis 2–10 mm, ± flattened; leaflets (3 or)4 or 5(–7), blades obovate to elliptic-lanceolate or ovate, apex acute, surfaces densely sericeous. Peduncles ascending, 0–6(–40) mm, shorter to longer than leaves; bract absent or unifoliolate, subtending umbel. Inflorescences 3–20-flowered, capitate. Flowers 6–12 mm; calyx 5–7 mm, tube densely villous, lobes subulate, shorter than or equal to tube; corolla yellow to orange, turning red or brown, claws shorter than calyx tube, banner implicate-ascending, wings ± equaling keel; style curved, glabrous. Legumes persistent, included to moderately (–strongly) exserted, ascending to divergent, reddish brown, arched, turgid, not constricted, not septate, lanceoloid, 6–10 × 1–2 mm, leathery, apex short-beaked, tapering, curved or geniculate, indehiscent, smooth, margins keeled smooth, glabrate to silky. Seeds 1 (or 2), tawny, mottled, curved-oblong, elongate, smooth.

Distribution

California, nw Mexico.

Discussion

Varieties 6 (5 in the flora).

D. Isely (1981) reported a potential hybrid between Acmispon argophyllus (variety not specified) and A. glaber (variety not specified). Variety ornithopus (Greene) Brouillet is endemic to Guadalupe Island (Baja California, Mexico). In a phylogeographic study of A. agrophylus, L. E. Wallace et al. (2017) showed that the insular endemic varieties are distinct, although var. argenteus is paraphyletic to var. adsurgens, with var. niveus of Santa Cruz sister to all remaining varieties in the species, including the continental ones.

Selected References

None.

Lower Taxa

Acmispon argophyllus var. adsurgens, Acmispon argophyllus var. argenteus, Acmispon argophyllus var. argophyllus, Acmispon argophyllus var. fremontii, Acmispon argophyllus var. niveus

Key

1	Herbs, perennial; stems prostrate or decumbent-ascending; mainland California.	> 2
2	Umbels 3–7-flowered, not congested, peduncles 1–6+ mm; calyces 5–6 mm, lobes 1.5–2(–3.5) mm; banner claw shorter than blade; s Sierra Nevada, s California ranges.	Acmispon argophyllus var. argophyllus
2	Umbels 10–15-flowered, congested at branch tips, peduncles 0–2 mm; calyces 6–7 mm, lobes 2–3(–5) mm; banner claw scarcely shorter than blade; n Sierra Nevada.	Acmispon argophyllus var. fremontii
1	Subshrubs (mostly); stems ascending to erect, sometimes prostrate; Channel Islands.	> 3
3	Umbels 12–20-flowered, peduncles 5–40 mm.	Acmispon argophyllus var. argenteus
3	Umbels 6–13-flowered, peduncles 1–5 mm.	> 4
4	Stems ascending to erect, densely leafy; umbels 10–13-flowered; San Clemente Island.	Acmispon argophyllus var. adsurgens
4	Stems ascending to bushy and spreading, not densely leafy; umbels 6–10-flowered; Anacapa and Santa Cruz islands.	Acmispon argophyllus var. niveus