2005 Volume 56 Issue 3 Pages 241-246
Somatic chromosome numbers were counted in seven species and six varieties of Isodon occurring in Japan. All of the taxa had 2n=24 chromosomes, indicating that they are diploid. For all taxa except I. umbrosus var. hakusanensis and I. japonicus, chromosome numbers are reported here for the first time. The results suggest that diversification in Japanese taxa of Isodon has occurred at the diploid level, even though some reticulation had been suggested by a preliminary molecular study.