Peduncles sessile-glandular. Phyllaries usually sessile-gland-ular, rarely tomentose, the longer 10-15 mm. 2n = 36. Flowering Jul-Sep. Mostly wet, disturbed sites, oil-seed or irrigated crops, roadside ditches, along streams, wetlands; 0-2200. m; introduced; Alta., B.C., Man., N.B., N.S., Ont., P.E.I., Que., Sask., Yukon; Calif., Colo., Conn., Del., Idaho, Ill., Ind., Iowa, Kans., Maine, Md., Mass., Mich., Minn., Miss., Mont., Nebr., Nev., N.J., N.Y., N.C., N.Dak., Ohio, Oreg., Pa., S.Dak., Tenn., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Europe; widely introduced elsewhere. Subspecies uliginosus is considered a noxious weed in Alaska, Idaho, Illinois, Iowa, Maryland, Minnesota, North Carolina, North Dakota, South Dakota, and Wyoming.