Annual, erect or ascending, glabrous herb; branches elongate, internodes long, stem 4-5 angled; leaves opposite, linear-lanceolate, glabrous; flowers purple-rose-coloured, in 12-15 cm long, terminal or axillary, elongated spikes; bracts linear, obtuse, glabrous; bracteoles similar to bracts, linear-oblong, glabrous, scarious margins, usually as long as calyx; sepals-4, linear, tip obtuse, equal, glabrous, hardly broader than bracts; corolla small, violet with purplish blotches, 2-lipped, tube short or equal to limbs, upper lip entire, 2-lobbed, lower 3-lobed, imbricate in bud; stamens-2, scarsely exserted, anthers 2-celled, oblong, filaments dilated, hairy at the base; ovary glabrous, style hairy below; capsules small, 4-seeded, ellipsoid; seeds much larger, ovoid, compressed, smooth, concentrically tuberculate or rugose.