Annual or perennial, erect, dichotomously branched, very slender, pubescent herb; rootstocks woody; leaves linear, flat, opposite, sometimes pseudo-whorled; stipules lanceolate, 1-nerved, very acute, scarious; flowers many, white with pinkish tinge, crowned on branches forming large, capitate cymes; pedicels short pubescent; bracts lanceolate, scarious or membranous, bifid at apex; sepals 5, scarious, white or often colored, linear-lanceolate, very acute, silvery, much exceeding the petals and capsules not keeled often veined with red; petals 5, red-pink, ovate or orbicular, 2-toothed, membranous; stamens-5, sub-perigynous, free or cohering together and with the petals into a tube; ovary 1-celled, style slender or 3-fid, ovules many; capsules 3-valved, globose, entire, brown, shiny; seeds obovoid, compressed, light brown.