Erect, annual, glabrous herbs; stems reddish green; leaves linear-lanceolate, narrowed to the base; petiole short; flowers very shortly pedicelled, yellow, axillary, solitary or paired, tetramerous; calyx tube scarcely produced above the ovary, teeth 3-5, linear, acute, persistent; petals-4, yellow, small, elliptic; stamens as many as calyx lobes, rarely more; filaments slender; ovary 4-5 celled; ovules many in 2 or more rows; style slender; stigma capitate; capsules linear-oblong, thin walled, 4-angled or terete, pale brown; seeds many, multiseriate in each cells, free, brown, without coma, ellipsoid or rounded.