Perennial or shrubby herbs without cystoliths. Leaves opposite or in whorls, with scattered peltate subsessile orange glands beneath. Flowers one per bract, alternate, in terminal lax or dense racemoid cymes, pedicellate; bracts fused to the pedicel, persistent, 3-veined from base; bracteoles similar to the larger sepals, inserted on base of calyx and covering the lateral sepals. Calyx deeply divided into 5 unequal sepals, two lateral small, hyaline, 1-veined, dorsal and two ventral herbaceous, 3-veined. Corolla 2-lipped; tube linear, broadening gradually upwards or abruptly campanulate; upper lip flat or ± hooded, entire or emarginate, lower deeply 3-lobed with two narrow lateral lobes and broad rounded central lobe with 2–4 bosses at base. Stamens 4, didynamous, inserted deep in the tube, included or shortly exserted; filaments linear; anthers 2-thecous, thecae elliptic, with small apiculus at base, divergent, inserted at same height on a broad connective; staminode absent. Ovary 2-locular, with 6–8 ovules per locule; style linear; stigma deeply 2-lobed with 2 linear lobes, or lower lobe reduced, the upper lobe bifid. Capsule sessile, oblong-triangular, obtuse, glabrous, apical part sterile and ± recurved when mature; retinaculae papilliform, unindurated. Seed black, ovoid, flattened, rugose, with a hilar excavation.