Stem erect, dichotomously branched, quadrangular, retrorsely aculeolate hairy on angles. Leaves 6 in a whorl, oblanceolate, 10-15 x 2-4 mm, margin minutely scabrid, attenuate, mucronate-cuspidate. Inflorescence dichotomously branched, cyme 1-flowered, peduncle 15-25 mm long. Corolla white. Fruit c. 3 mm broad, densely covered with long hooked bristles.