Annual or pertnnial glabrous herbs with decumbent stems. Leaves entire, all alternate or the lower ones sometimes opposite; stipules small, scarious. Flowers small, in axillary or terminal, dense, cymose inflorescences, minutely bracteate. Calyx persistent, parted into 5 white-margined lobes. Petals 5, free, as long as or longer than calyx. Stamens 5, inserted on the margin of the short perigynous disk. Ovary ovoid, 1-celled, with 1 ovule inserted at the apex of a long funicle; style 3-parted, very short. Fruit an indehiscent, 1-seeded, trigonous nutlet, enclosed in persistent calyx. Seed with membra¬nous coat; embryo annular, surrounding the copious endosperm.