Description

Key Characters:

Growth Form: Shrubs 0.75–1 m tall.

Stems: Stems unarmed, densely branched, the branches decumbent, 0.75–1.5 m long, the new growth densely brown hirtellous–villosulous with straight and curly, white and brown simple trichomes 0.1–0.3 mm long, the twigs 2–4 mm diam. brown, longitudinally ribbed or angled, becoming whitish gray with corky fissures, knobby with large rounded buds and persistent stipules and leaf bases, the leaves clustered near twig tips, brachyblasts absent:.

Roots:

Leaves: Leaves compound (bipinnate). Alternate. Leaflets unequal–sided, ovate–elliptic, 1.4–4.2 x 0.9–3.2 cm, each leaf with one pinnae pair, 22–55 mm long, each pinna bearing a pair of terminal leaflets and a single smaller proximal leaflet basally, the pulvinules hirtellous, 1–1.5 mm long, the rachis terminated by a short, acute brown appendage. Apex obtuse or rounded. Base the base truncate to subcordate. Surfaces stiffly chartaceous, discolorous, finely strigillose below when young. Margins ciliolate. Veins pinnate, the 2nd degree veins 3–4 on a side, the ultimate venation finely reticulate, visible to 5 degrees on both surfaces. Petioles 6–24 mm long, 0.8–1 mm diam. white hirtellous and brown villosulous, apically with a single leaf nectary adaxially at junction with pinnae, 0.5–0.8 mm diam. ellipsoid, sessile, the margin hirtellous. Stipules free, paired, ovate, 1.5–2 mm long, 1.2–1.5 mm wide, densely villosulous, the apex acute, antrorsely curved, the thickened bases persistent, transversely fissured.

Flowers: Flowers in inflorescences globose, 1–3 per leaf axil, developing with a flush of new leaves, 20–54 flowers per capitulum. male and female flowers borne in separate inflorescences. the peduncle 8–30 x 0.4 mm, hirtellous, the capitula 6–8 mm diam. including stamens. Flowers mimosaceous, unisexual; bracteoles 1–1.5 mm long, the peltate apex villosulous. Calyx of staminate flowers with limb obconic, 1–1.3 mm long, densely white villosulous in apical ⅓; Calyx lobes 5, valvate in bud, 0.1––0.2 mm long, triangular, incurved, brown–villosulous. Corolla of staminate flowers valvate in bud, the petals 1.5–1.8 x 0.5–0.7 mm, oblanceolate, cucullate, apiculate, 1-veined, externally hirtellous apically, separate at base. Stamens in staminate flowers 10, exserted, the filaments 2–3 mm long, glabrous, connate at base, the anthers dorsifixed, ellipsoid, 0.6–0.8 mm long, glabrous, lacking glands, the dehiscence extrorse. Pollen tricolporate, in monads; spheroidal to subspheroidal, with the polar and equatorial diameter range of 26–41 micrometers.

Fruit: Pods on a stipe 4–5 mm long; up to 4 per capitulum; 2.4–3.2 x 2–2.3 cm; obovate or subcircular; compressed; coriaceous; externally hirtellous basally; with transverse cross veins; 2–valved; inertly dehiscent along both thin margins; the valves separating into inner and outer envelopes. Seeds 1 per fruit; cordiform; brown; 1–1.3 x 1.1–1.6 cm; the slender brown seed funicle 2–3 mm long.

Ploidy: 2n = 28

Habitat: Growing on steep; rocky talus slopes at elevation with a substrate consisting of oxisols derived from basaltic lavas.

Elevation Range: 45–60 m.