22 Botrychium simplex Hitchc.

This variable species is disjunctly distributed in Europe, Japan and N. America. An especially thinstemmed type, var. tenebrosum (A. A. Eat.) Claus., occurs in eastern N. America and on Greenland. It is also reported from Japan, very rarely in C. Honshu mountains (Ohwi, Fl. Japan 1965, p. 30). The occurrence on NE. Hokkaido (Yezo) is not verified in op. cit. The species belongs to the amphi-atlantic plants (Hultén, Amphi-atl., p. 212 and map 193). Cf. also Meusel et al. 1965, map p. 11.