Herbs with opposite, decussate, rarely whorled leaves. Inflorescence spicate, rarely pseudumbellate or fascicled, terminal, rarely axillary. Flowers bisexual, small or moderate in size, bracteate. Calyx tubular, 5-ribbed, unequally shortly 5-toothed, not enlarging in fruit. Corolla salver-shaped, 5-lobed, somewhat bilabiate and lobes subequal, oblong to obovate. Stamens usually 4, didynamous, not exserted; anthers ovate, connective with or without a glandular appendage. Carpels 2, syncarpous; ovary entire to 4-lobed, 4-loculed with 1 ovule in each locule; style reaching the level of stamens. Fruit schizocarpic, enclose ed within the calyx, separating into four, 1-seeded nutlets; seeds oblong, angular.
About 250 species, chiefly American; represented here by 4 species.