Usually ascending annual. Stems with a stripe of hairs at young tips, ± glabrous or evenly moderately hairy below, branched or not from base, up to 40-(50) cm long. Lvs opposite, ± glabrous above and below, or sparsely hairy near base, shortly petiolate, serrate, elliptic-oblong, acute to obtuse, asymmetric at base, (8)-10-30 mm long, often with a reddish purple spot about midvein; stipules triangular, serrate, at least partly fused, 1-2 mm long. Cyathia solitary at nodes or in small axillary leafy clusters along branches; subtending lvs similar to stem lvs. Glands ovate, with large white or pink petaloid appendages. Capsules smooth, glabrous, grooved, with sharp keels. Seeds rugulose, 4-angled, dark brown to black, c. 1.2 mm long.