Herbs or shrubs. Lvs usually opposite, decussate, rarely alternate or whorled, entire or nearly so. Fls 6-merous, zygomorphic, monomorphic, solitary or in racemes, sometimes in verticels; pedicels usually interpetiolar rather than axillary; bracteoles 2 or 0. Calyx tube ± curved, ribbed, usually pouched or spurred at base, often coloured, oblique, usually with an epicalyx tooth between each lobe. Petals 6, rarely fewer or 0, unequal, shortly clawed, inserted near rim of calyx tube. Stamens 6-14, rarely fewer, inserted on upper 1/2 of calyx tube, included or exserted. Disc at base of ovary glandular, asymmetric. Ovary sessile, 2-celled but septum often disappearing early. Ovules 2-many in each cell. Stigma 2-lobed. Capsule enclosed by calyx, dehiscing longitudinally.