Betula ermanii Cham.

in Japan, Honshu, Mt. Fuji, May 2008 (pictures 1 to 13)
in South Korea, Jeju island, Hallasan, September 2011 (pictures 14 to 19)
in Japan, Honshu, Gomi Pond, June 2010 (pictures 20 to 25)
in Japan, Honshu, Mt. Higashitate, June 2010 (pictures 26 & 27)

Description in Linnaea 6: 537, t. 6. fig. D. 1831