Ascending to erect herb to 80 cm high, often rhizomatous, frequently rooting at the nodes; branches glabrous or with a few scattered hairs, often reddish- or purple-tinged. Leaves narrowly to broadly ovate or broadly elliptic, 15–90 mm long, 10–30 mm wide, glabrous or with scattered hairs, apex acute or obtuse, margin serrate to dentate; petiole 0–15 mm long. Inflorescence terminal, ovoid to spike-like, 1.5–6 cm long; flowers in dense, many-flowered clusters, internodes usually obscured; pedicels c. half to equal to calyx. Calyx 2.5–4 mm long, 10-veined, lobes c. half as long as tube, glabrous or with scattered hairs along medial ridge and often ciliate on lobe margin; corolla lilac to pink, exceeding calyx by 1–2 mm, lobes 1–1.5 mm long, the posterior one emarginate to bilobed; anthers included. Flowers Jan.–Apr.