Annual or perennial, erect, nearly glabrous undershrub; stem swollen at the nodes; leaves opposite, ovate or lanceolate, acuminate or subobtuse, tapering at the base into a short petiole, dark-green above, paler beneath, entire, rather coriaceous; flowers in dense, terminal spikes; bracts large, foliaceons, abovate-rhomboid, acute or subacuminate, pubescent, palegreen margin more or less toothed, bracteoles 2, linear, small; calyx 5-partite, linear, narrow, equal or unequal, connate below; corolla bilabiate, upper lip narrow, shortly 2- fid, lower 3- lobed, lobes imbricate in bud, tube long, slender; stamens 2, adnate to the top of corolla tube, anthers 2 celled, cells parallel, subequal, muticous; ovary glabrous or hairy, 2-locular, ovules 2 in each, style filiform, stigma very shortly bifid, capsule ovoid, compressed, long stalked, puberulous; seeds 4 or 2, compressed, orbicular.