Shrubs. Branches divaricate; sterile shoots sharp-tipped. Stems 4–9(–15) dm, gland-dotted when young, silky-pilosulous, hairs retrorse. Leaves pinnate, (1–)1.4–3 cm; leaflets 7–17(or 19), blades obovate, oblanceolate, linear-oblanceolate, or linear-oblong, 2–7 mm, ter­minal leaflet shorter than laterals, surfaces sparsely gland-dotted abaxially, strigulose, more strongly so adaxially. Racemes loose and open; rachis not spine-tipped in anthesis, (1–)2–9 cm; bracts ovate-elliptic, 0.6–1.5 mm; bracteoles absent. Flowers: calyx 3.7–5 mm, pilosulous throughout, or tube glabrous, lobes pilosulous, tube 2.4–3.3 mm, ribs prominent, intervals each with 1–4 large glands, lobes ovate to oblong-ovate, abaxial lobe shorter; corolla pink- to violet-purple; banner (5.5–)6–8.4 mm, ovate to suborbiculate, base cuneate or cordate, claw linear; wings oblong, 5.8–6.6 × 2.6–3.2 mm; keel obovate, 5.6–6.7 × 3.4–3.8 mm; stamens 6–7.7 mm; filaments distinct to 2.5–3.5 mm; anthers 0.8–0.9 mm, connective gland-tipped. Legumes obliquely obovoid, 4–4.5 mm, with large glands distally, glabrous proximally, sparsely pilosulous distally. Seeds 2.1–2.6 mm.

Distribution

sw United States.

Discussion

Varieties 2 (2 in the flora).

Selected References

None.

Lower Taxa

Psorothamnus thompsoniae var. thompsoniae, Psorothamnus thompsoniae var. whitingii

Key

1	Leaflet blades obovate or broadly oblanceolate, 2–4(–5) mm; calyx tube usually glabrous, lobes pilosulous, sometimes pilosulous throughout.	Psorothamnus thompsoniae var. thompsoniae
1	Leaflet blades linear-oblanceolate or linear-oblong, 3–7 mm; calyx usually pilosulous throughout.	Psorothamnus thompsoniae var. whitingii