kenta watanabe

Heterostyly is a genetically controlled floral polymorphism that promote outbreeding. Although many studies on heterostyly have been done in Japan, there have been no comprehensive analysis nor review. Here I present the list of heterostyly in the native flora of Japan through reviewing references. By using this list, I tested the difference in occurrence of heterostylous species among subgroups of islands. Then I also tested the difference in growth forms and a dispersal mode between northern and southern part of Japanese islands. Finally, I briefly reviewed studies on heterostyly in Japan, special emphasis on maintenance and breakdown of heterostyly in the wild population.
After the examination of the literature and screening process, 36 heterostylous species were recognized in Japan (0.72％), which is slightly lower than the world estimate (1%, Renner 2014). There was no significant difference of occurrence among three geographical areas. More woody and zoochory (dispersal by animals) species in the southern islands compared to temperate islands. This is the first report of the species-based estimate of the proportion of heterostyly in Japan.