Erect, strict, glabrous annuals. Leaves simple, alternate, erose. Flowers hermaphrodite, very small, sessile, clustered in the axils or short axillay cymes, branches ± spinulose; bracts and bracteoles absent. Perianth segments 5, subacute, green. Stamens 1-3; filaments dilated below. Ovary depressed with short style and 2 subulate stigmas; ovule erect. Fruit (utricle) disciform, depressed, circumscissile. Seed horizontal with black, shining testa, exalbuminous; embryo annular.