Rep. U.S. Mex. Bound. 2(1): 121. 1859.
Shrubs, often pendent, lax, 3–15 dm. Stems much-branched, glandular-tomentose when young. Leaves: stipular lines faint; petiole 5–20 mm; blade ovate-oblong or lanceolate, 3–10 × 1.5–4 cm, base hastate, cuneate, or truncate, margins irregularly dentate, crenate, or subentire, apex acute, abaxial surface appressed-tomentose or with stellate hairs, always with glandular-hairs, adaxial glabrous or glabrate. Inflorescences terminal, racemose, 3–10 × 1.5–4 cm, cymes capitate, 4–28 pairs, 6–12-flowered. Pedicels absent; bracteoles absent. Flowers slightly fragrant; calyx tomentose and glandular externally, tube 1–1.7 mm, lobes 0.5–0.8 mm; corolla pale-yellow, funnelform, salverform, or campanulate-rotate, tube 1.5–2.4 mm, lobes orbiculate, 0.7–1 × 1–1.5 mm; stamens inserted in distal 1/3 of corolla-tube, included in tube; ovary ovoid, 0.7–1.2 mm, glandular-tomentose; stigma clavate, slightly 2-lobed at apex, 0.5–0.7 mm. Fruits capsules, brown, ovoid, 2–2.5 × 1.7–2 mm, glandular-tomentose, dehiscence septicidal and loculicidal. Seeds ellipsoid, 0.5–0.6 × 0.2–0.3 mm, wings absent.
Varieties 2 (2 in the flora).