Subshrubs, to 0.8 m, herbage densely ± yellowish stellate-tomentose throughout. Stems: older twigs yellowish brown, glabrescent, line of fine hairs obscured by other pubescence or absent. Leaves: stipules narrowly triangular to subulate, 1–3 mm; petiole to 1/2 as long as blade, adaxial fine, curved hairs absent or obscured by other pubescence; blade oblong or broadly to narrowly ovate (often folded in pressed specimens), usually unlobed, rarely shallowly 3-angulate-lobate, mostly 1.2–3 × 1–2.5 cm, base cuneate to rounded or truncate, margins irregularly and coarsely dentate or dentate-crenate, apex broadly acute to truncate, surfaces stellate-tomentose, ± obscured nectary present abaxially on midvein near base. Inflorescences solitary flowers in axils of distal leaves. Pedicels obscurely joined below apex, 0.5–2 cm, equaling or exceeding subtending petioles; involucellar bractlets 7–10, often absent, narrowly triangular to subulate, to 0.6 cm, margins not ciliate. Flowers ascending to erect; calyx divided 2/3–4/5 length, funnelform, 0.7–1.6 cm, lobes narrowly triangular-ovate, apices acuminate, nectaries absent; corolla rotate, petals pale purple or pink to nearly white, with maroon spot or lines basally, asymmetrically obovate, 1.3–3 × 0.9–2 cm, margins ± entire, finely hairy abaxially where exposed in bud; staminal column straight, pink, 0.4–1.1 cm, bearing filaments throughout, free portion of filaments not secund, 1–3 mm; pollen dark orange; styles pale pink, 1.5–4 mm; stigmas pale pink to maroon. Capsules dull yellow-green with darker medial stripe on each valve, drying straw-colored, ovoid to subglobose, 0.6–1 cm, shorter than calyces, apex apiculate, glabrous or with minute hairs near apex and on sutures. Seeds dark brown, angulately reniform-ovoid, 2.2–3 mm, whitish, silky-hairy ± throughout, hairs 3–4 mm. 2n = 22 (Mexico: Durango).
Phenology: Flowering year-round.
Habitat: Desert, often rocky
Elevation: 30–1800 m
Ariz., Calif., Nev., N.Mex., Tex., Mexico (Baja California, Baja California Sur, Chihuahua, Coahuila, Durango, Sonora).
Hibiscus denudatus has been recorded from Imperial, Riverside, San Bernardino, and San Diego counties in southern California; from southernmost Nevada (southern Clark County); from the southern half and near the Grand Canyon in Arizona; from southwestern New Mexico; and from the region west of the Pecos River in Texas.
As noted in the previous species, a naturally occurring hybrid between Hibiscus denudatus and H. coulteri (Hibiscus ×sabei Weckesser) has recently been documented from western Texas (W. Weckesser 2011).