Erect perennial (occasionally annual) herb, usually to 60 cm high, sometimes to 2 m high, usually well-branched at the base; stems with a fine pubescence of coiled hairs on ridges decurrent from leaf bases and often with numerous glandular hairs especially in the flowering regions. Leaves opposite on lower stems, alternate near inflorescences, lanceolate, 2.5–12 cm long, 5–30 mm wide, glabrous but for a few hairs on margins, petiole and main vein, margins with numerous tiny teeth, apex tapering or acuminate, base broad and rounded; petiole 1–3 mm long. Flowers with a conspicuous ring of long hairs inside the hypanthium; sepals linear-triangular, 2–4 mm long; petals white or purplish-pink, 3.5–5.5 mm long. Capsule 4.5–8.5 cm long, with a close, partly glandular pubescence; pedicel 0.3–1 cm long; seeds 0.9–1.2 mm long, comose, surface with laterally flattened papillae in obvious longitudinal lines. Flowers mainly Nov.–Mar.