Undershrub or shrub, stem often whitish green; branches striated; leaves alternate, elliptic to ovate, acute, abruptly attenuated into a petiole with dilated amplexicaul base, glabrous or puberulous; flowers many in terminal, branched spikes; calyx densely covered with stalked glands, persistent, teeth-5, linear-subulate, very short; corolla tube about 2.5 cm long, white, lobes-5, oblong, apiculate; stamens-5, free, very shortly united at the base of corolla tube, anthers bluish-purple; ovary 2 celled, ovule 1 in each locule, placenta basal; style-1, filiform, glabrous, 5-fid or divided into 5-stigmatose branches; stigma capitate; capsules oblong, acute with 5-furrows, 5-valves, circumciss near the base; calyx persistent and recurved; seeds solitary, black, flattened.