Sp. Pl. 1: 12. 1753.
Introduced; B.C., Ont., Que., Calif., Conn., Ill., Maine, Mass., Md., Mich., Mo., N.J., N.Y., Nev., Ohio, Pa., Va., W.Va., Wis., Eurasia, Africa, introduced also in s South America.
Subspecies 3 (1 in the flora).
Subspecies abscondita M. A. Fischer is found from eastern Turkey to western Iran, while the native range of subsp. muscosa (Korshinsky) Elenevsky extends from eastern Iran to southern China.