Annual, erect to spreading to scrambling herb, usually 20-80 cm long. Stem stout, quadrangular, angles retrorsely and strongly scabrid. Leaves 6-8 in whorl, sessile, linear, lanceolate, oblanceolate or spathulate, cuspidate, margin and dorsal midrib retrosely aculeolate, margin revolute, 10-50 x 2.5-8 mm. Cymes axillary mostly 3-flowered, rarely 1-flowered, lateral flowers usually functionally male. Peduncle 5-40 mm long, retrorsely aculeate, pedicel 1-10 mm long, incurved after anthesis. Corolla white, glabrous, segments ovate, acute, c. 1 mm long. Fruit globose-ellipsoid 3-5 mm, granulate or minutely tuberculate, mericarps mostly 2.