An erect, annual to short-lived perennial, aromatic herb, 40—100 cm tall, stem much branched, prominently 4-angled, nearly glabrous. Leaves are decussate, ovate to oblong-ovate, 2—6 cm x 1—3.5 cm, base acute or attenuate, apex acuminate or caudate, margins irregularly serrate, thin-membranaceous, glabrous on both surfaces, or minutely gland-dotted underneath; petiole slender, 1—4 cm long; stipules absent. Inflorescence consisting of cymes, together resembling a terminal or axillary, slender raceme or panicle, 3—6 cm long, in fruit over 10 cm long; bracts minute, lanceolate, aristate, 1—2 mm long. Flowers small, bisexual; pedicel 1—1.5 mm long; calyx campanulate, 1.5—2 mm long, in fruit 3—3.5 mm long, slightly inflated at the base, 5-toothed, teeth short, the distal one broad, obtuse, abruptly acuminate, the other 4 much smaller, triangular, acute, pubescent; corolla funnel-shaped, 2—2.5 mm long, tube 1.8 mm long, 2-lipped, upper lip broad, entire, reflexed, lower lip 3-lobed, 2 lateral teeth cuspidate, a few short hairs outside, pale lilac, purple or flesh-coloured, sometimes white; stamens 4, didynamous, included, filaments inserted on the corolla tube, glabrous, anthers 1-celled; disk symmetrical; ovary superior, glabrous, style with short, 2-lobed stigma. Fruit consisting of 4 dry, 1-seeded schizocarpous nutlets, broadly ellipsoid, compressed, 0.5 mm long, smooth, dull brown. Seedling with epigeal germination; cotyledons petiolate, blade broadly ovate, base obtuse, apex emarginate, margin with sparse minute bristles; hypocotyl elongate, bristly in rows, epicotyl up to 1 mm long, 4-angular, bristly.

As a sedative (crushed leaves)

PROSEA (Plant Resources of South-East Asia) Foundation

Used to relieve painful sprains and limbs (crushed leaves); for epilepsy, palpitations of the heart, neuralgia, nervous headaches, nervousness after childbirth, rheumatism and convulsions (decoction of leaves); chewed against cough, or cooked with food to reduce flatulence (roots); for parturition in the case of delayed birth (infusion of fruit); the leaf-sap is squeezed into the nostrils of children to cause sneezing, in order to cure headache.