Plants herbaceous, mound-forming, perennial, 10-40 cm tall; root stock woody, branched. Stems many, erect to ascending, glabrous to sparsely pubescent, hairs minute; nodes swollen. Leaves opposite, linear, 7-30 mm long, 1-2 mm wide, reduced in size upwards, usually congested basally, surfaces glabrous, margins more or less sparsely ciliate, midrib thick, tip acute.