108 Potamogeton berchtoldii Fieb.

Syn.: P. pusillus auct., non L.

This variable and widespread, Eurasiatic and N. American species is named P. pusillus (even with L. as author) by several authors (Hultén, Circumpol. I, p. 126 and map 117), Hultén, Atlas 1971, map 105, and Lid Flora 1974, p. 70. Cf. also no. 107 P. pusillus. The distribution is circumpolar (Hultén, Circumpol. I, I. cit.). However, the distribution is uncertain, especially in Asia. A Greenland population has been distinguished as P. pusillus subsp. groenlandicus Böch. but later transferred to another subsection (cf. Hultén, Circumpol. I, p. 126).