Perennial herb, rhizome lying horizontally underground, robust; stem erect, much-branched, 30-100 cm tall, entirely greenish, slightly hairy or densely pubescent, branches usually quadrangular. Leaves alternate or in whorls of three, lanceolate or broadly lanceolate, 4-6 (-10) cm long, 8-15 mm wide, apex obtuse or shortly acute, base rounded or cordate, sometimes slightly clasping the stem, entire, without petiole.