Endemic dwarf birch Betula apoiensis (Betulaceae) is a hybrid that originated from Betula ermanii and Betula ovalifolia

Betula apoiensis (Betulaceae), a tetraploid endemic to Mount Apoi in Hokkaido, is endangered in Japan. To reveal the origin of this species, the internal transcribed spacers and 5.8S gene of nuclear ribosomal DNA (ITS + 5.8S) and a microsatellite with its flanking region of nuclear DNA (Bp09) were sequenced and their haplotypes were determined for 12 Betula species in the Sakhalin, Hokkaido and Honshu Islands. The most parsimonious trees of ITS...