Cytogeography of glechoma Hederacea subsp. grandis (Labiatae) in Japan

Abstract

In this study, we examined the chromosomal number for Glechoma hederacea subsp. grandis in a total of 1,030 specimens collected from different distribution areas in Japan. We found that G. hederacea subsp. grandis could be categorized into 3 cytotypes with 2n=36 (tetraploid), 2n=45 (pentaploid) and 2n=54 (hexaploid) chromosomes. Tetraploid plants were found throughout different areas in Japan; however, hexaploid plants were mainly distributed in central Honshu, Shikoku and Kyushu. Likewise, pentaploid plant distribution was found to overlap with hexaploid plant distribution areas. The pentaploid plant group appeared only in regions common to both tetraploid and hexaploid plants. All 3 cytotypes were found to have karyotypes which could be represented by the following equations: A) 6M+4m+18sm+8st for tetraploids, B) 6M+15m+19sm+5st for pentaploids, and C) 6M+26m+20sm+2st for hexaploids. Pentaploid specimen karyotypes had half the tetraploid and half the hexaploid chromosomal set, indicating that this specimen was a hybrid between tetraploid and hexaploid plants. © 2010 The Japan Mendel Society.