Perennial herb, thickened rootstock usually producing annual stems to 1 m high including inflorescence, sometimes scandent to 2 m high in bushes; all parts glabrous. Leaves ± fleshy, sessile, 2–9(–14.5) x 1–3(–5.5) cm, obovate to oblanceolate, base cuneate, apex rounded-mucronate. Inflorescence a terminal, elongated, often raceme-like, panicle; lower bracts leaf-like, upper much smaller; lateral peduncles 1–3(–6)-flowered, to 15 mm long. Pedicels 7–15 mm long, curving down in fruit; bracteoles 1–4 mm long, membranous. Sepals 4–6 mm long, ovate, tip apiculate. Petals obovate, 9–12 x 5–6 mm, purple, sometimes paler, almost white. Stamens c. 25, filaments yellow. Capsule globose, 5–7 mm diam. Seeds c. 1.2 mm diam., black, glossy, obscurely patterned with concentric rings of oblong cells.