Perennial herbaceous plant, rhizome lying horizontally underground, robust; stem erect, much-branched, 30-100 cm tall, entire plant 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.
The flowers form small paniculate inflorescences, grouped together, appearing as a large spike-like inflorescence due to very short pedicels and rachis. The bracts are broadly lanceolate to triangular-ovate, measuring 5-12 mm in length. The calyx tube is 5-8 mm long, with 12 longitudinal ribs, slightly covered with coarse hairs, and 6 triangular lobes. The appendages are needle-like, erect, and 1.5-2 mm long. There are 6 petals, either purple or pale purple, obliquely lanceolate-elliptic, with a cuneate base, 7-8 mm long, attached to the upper part of the calyx tube, featuring short claws and slight wrinkles. There are 12 stamens, 6 long and 6 short, extending beyond the calyx tube; the ovary has 2 chambers, with a stylus of varying lengths. The capsule is flattened, roundish.