An erect, glabrous, ± glaucous annual herb not usually exceeding 15 cm in height. Leaves sessile. Stem-leaves few, alternate or subopposite; upper leaves all opposite. Leaf-blades all linear, 0.5-2.5 cm x 0.5-1 mm, subacute or obtuse, entire. Branching repeatedly dichotomous in the upper ½ or 2/3 of the plant, at some nodes occasionally trichotomous, with the cyathia solitary in the forks of the dichotomies; axillary shoots also present, sometimes arising from the cotyledonar axils. Glands minute, transversely ovate, dark purple. Fruits ovoid-trilobate, 2.5 x 2.2 mm, smooth. Styles free, 0.5 mm long, bifld, stigmas thickened upwards. Seeds cylindric, hexagonal, 2 x 1 mm, longitudinally sulcate, transversely rugulose, pale grey, with a stipitate, discoid caruncle.