652 Polygonum amphibium L.

This polymorphic species s. lat. is widely distributed in Eurasia and N. America. The Eurasiatic subsp. amphibium, the E. Asiatic subsp. amurense (Korsh.) Hult. and the N. American subsp. laevimarginatum Hult. (syn.: var. stipu/aceum [Coleman] Fem.) are mapped separately. The European taxon has been introduced into many extra-European countries, also to N. America. This species s. lat. belongs to the circumpolar plants (Hultén, Circumpol. Il, p. 174 and map 166). Cf. also Meusel et al. 1965, map p. 130.