Small shrub, 1-2.5 m tall, with subcylindrical, glabrous branches. Leaves opposite-decussate, ovate to elliptic, 3-6 cm long, 1.5-2.5 cm broad, serrate, cuneate, scabrous, shortly petiolate; petiole 1-1.5 cm long. Spikes elongated, up to 25 cm long, slender, glabrescent or sparsely pubescent. Flowers blue with whitish centre, c. 5 mm across, bracteate with linear-lanceolate acuminate bracts. Calyx-tube 4-5 mm long, 4-toothed, glabrous. Corolla-tube as long or slightly exceeding the calyx; limb 4-5-lobed, with lobes 1.5-2 mm long. Fruit with persistent style, splitting into two, 1-seeded pyrenes.