Herb or scandent, diffused undershrub; leaves alternate or opposite, lanceolate or elliptic-obovate, apex obtuse or mucronate, tapering into a short petiole; flowers in elongated spikes, rachis glandular, striate; bracts-bractioles shorter than calyx, sepals-5, connate into narrow, persistent tube, densely covered with stalked glands; teeth small with membranous margins; petals-5, connate into a short tube, about 4 cm long, limbs spreading, pale blue or violet; stamens-5, free included in corolla tube; oppsite the petals, filaments nearly free, rarely adnate below to the corolla, anthers oblong; disk absent; ovary inferior, narrowed towards apex, 2 celled, ovule 1 in each locule, placenta basal; capsule included 5-valved, membranous, circumciss near the base.