The origin and presence of M. ‘‘integrifolia’’ in
both hemispheres remain unresolved; on the basis
of chloroplast DNA, Druehl and Saunders (1992)
suggested that M. ‘‘pyrifera’’ and M. ‘‘integrifolia’’
were either separated prior to trans-hemispheric dis-
persal or diverged subsequent to dispersal through
the equator during the Pleistocene glaciations. Dru-
ehl and Saunders (1992) revealed low sequence
divergence between M. ‘‘pyrifera’’ and M. ‘‘integrifolia’’
from the Northern Hemisphere (0.08%), but sam-
ples of M. ‘‘integrifolia’’ between hemispheres had
higher divergence (0.3%).