Perennial; stems slender, 2-6 dm, minutely and sparsely retrorse- scabrous on the angles, not bearded; lvs in whorls of 2-6, linear to narrowly oblanceolate, 5-15 mm, blunt, antrorsely ±scabrous on the margins; infls many-fld, repeatedly forked, the short slender pedicels mostly ascending at anthesis, widely spreading or somewhat reflexed in fr; cor white, acutely 4-lobed, 4 mm wide; fr smooth, 2 mm; 2n=24, 48. Wet soil; Nf. and Que. to Conn. and N.J., and also in Europe. June-Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.