Erect, usually much branched perennial to 1 m, the principal internodes usually less than 2 cm; lvs subsessile, lanceolate to oblong or oblanceolate, 6-15(-20) mm wide, gradually acute, with 2 or 3 conspicuous lateral veins on each side; fls solitary in the crowded upper axils, 3-15 mm apart at maturity, white or nearly so, 4-5 mm; cal-lobes nearly as long as the cor; nutlets ovoid, 3-3.5 mm, white to pale brown, shining, smooth or sparsely pitted; 2n=28. Native of Eurasia, intr. as a weed of waste places from Que. to Minn., s. to N.J. and Ill. May-Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.