A perennial herb, 25-200 cm tall, with quadrangular, poorly ramified, ascending stem.Leaves decussately opposite, ovate or rhombic, 2-9(-12)cm x 1.5-5cm, cuneate at base,acute or acuminate at apex, serrate, glabrous or minutely pubescent, glandular-punctate; petiole 0.5-2(-4.5)cm long; stipules absent. Inflorescence an opposed cymearranged in terminal racemes, 7-29cm long. Flowers pedicellate; calyx 2.5-4.5mmlong (up to 12mm in fruit), bilabiate, gland-dotted; corollla 10-20mm long, tubular,bilabiate, white or (pale) lilac; stamens 4, long-protrudding from the corolla tube;ovary superior, style long-protruding, slender, with enlarged, club-shaped andshallowly cleft stigma. Fruit splitting into 4 oblong-ovoid nutlets, 1.5-2mm long,brownish, rugose. (Indonesia)