Betula grossa Sieb. & Zucc.

Pictures 1 & 2 in Japan, Honshu, Kyoto, May 2008 (cultivated)
Picture 3 in Japan, Honshu, Nikko, June 2010 (cultivated)

Description in Abh. Acad. Muench. iv. Abth. III. 228 (1846)