Morphology and Flower Pigments of Wild Evergreen Azaleas (Rhododendron sataense Nakai) in Southern Kyushu

Abstract

The origin of flower color variation in Rhododendron sataense Nakai, one of the most colorful wild azaleas in southern Kyusyu, was investigated.
The range of flower color variations and two other morphological characteristics, flower size and petal blotch, of R. sataense were almost the same as those of R. obtusum Planch. The latter whose natural habitat is in the Kirishima Mountains, and is thought to be an interspecific hybrid between R. kiusianum Makino and R. kaempferi Planch. Constitutions of flavonols in the petals, however, were quite different between the two species; R. sataense does not contain methylated flavonols, whereas the R. obtusum in a high percentage of the population.
We conclude, therefore, that the origin of flower color variations in R. sataense on Takakuma Mountains is not the result of the natural hybridization between R. kiusianum and R. kaempferi, although natural hybrids have been found on the Kirishima Mountains.