Shrubs to 6 m. Stems ± terete; young shoots glabrous. Leaves: petiole (2–)2.3–3.5(–4.5) cm; blade ovate, elliptic, or slightly obovate (widest at or near midpoint), (5–)11–13(–15) × (3–)5–7(–9) cm, base narrowly cuneate to rounded, margins distinctly toothed (proximalmost tooth averaging 2.4 cm distal to base), apex acuminate, surfaces glabrous or with few stellate hairs and glabrescent abaxially, glabrous adaxially. Inflorescences solitary, (8–)10–16(–20) cm, axis densely stellate-hairy. Pedicels 2–6(–11) mm, proximalmost averaging 4.5 mm, stellate-hairy; bract longer than flower, stellate-hairy. Flowers: sepals 3.5–5 × 1–1.5 mm, stellate-hairy; petals white, 6–8(–8.5) × 4–5 mm; filaments 4–6 × 0.2–0.3 mm, glabrous or with scattered, simple, straight or crinkled hairs to 0.7 mm; anthers ca. 2 mm; style 7–9 mm, glabrous. Capsules subglobose, 2.5–4 × 3.5–5.3 mm. Seeds 0.7–1 mm. 2n = 32.
Phenology: Flowering summer.
Habitat: Deciduous montane woods, usually in moist sites
Elevation: 500-1400 m
Ala., Ga., N.C., Pa., S.C., Tenn., W.Va.
Clethra acuminata is known from the mountains of adjacent Pennsylvania, Virginia, and West Virginia; it may yet be found in the mountains of western Maryland; no specimens have been seen from that state.