617 Populus tremula L.

This Eurasiatic species s. str. (subsp. tremula) and its Asiatic subsp. davidiana (Dode) Hult. partly overlap each other. Further, the closely related N. American P. tremuloides Michx, the Japanese P. sieboldii Miq. and the C. Asiatic P. rotundifolia Griff. are mapped. P. tremula and tremuloides have together a circumpolar distribution (Hultén, Circumpol. II, p. 180 and map 172). Cf. also Meusel et al. 1965, map p. 112.