Characteristics of dorsal leaf surface in the species of subgenus Rhododendron section Tsutsusi in Japan

摘要

Samples of dorsal [abaxial] leaf surfaces taken from 16 species of the subgenus Rhododendron section Tsutsusi were examined to establish distinctive characters indicative of the presence of Ryukyu azalea genes in Kurume azalea hybrids family. The Suzuki Universal Micro-Printing method was used to prepare microscope slides for examination with a light microscope, equipped with differential interference contrast optics. Specific characteristics of the epidermal cells, cuticular topography, and stomata and the existence of trichomes were studied. Eight groups of the 16 species could be characterized by dorsal leaf features alone. Because the frequencies and sizes of stomata overlapped among species, they were useless as taxonomic characters. Based onthese data, R. macrosepalum [R. linearifolium] and R. mucronatum var. ripense, which are original species of Ryukyu azalea, are clearly distinguishable from R. kaempferi, R. kiusianum and R. kiusianum var. sataense, which are generally considered to bethe original species of the Kurume azalea hybrids family.