Morphological and Molecular Analyses of Rheophytic Rhododendron ripense and Its Allied Dryland Species R. macrosepalum (Ericaceae)

Abstract

The areas along rivers and streams are composed of particular environmental characteristics, and plants growing within this environment, called rheophytes, are subjected to flash floods after heavy rainfall as a strong selective pressure. To identify potential hybridization of the rheophytic Rhododendron ripense Makino and its allied dryland species R. macrosepalum Maxim., we conducted morphological and molecular analyses of these plant species. These analyses revealed a high rate of hybridization and introgression from R. ripense into R. macrosepalum, suggesting that hybrid plants arising from R. ripense and R. macrosepalum may develop broader leaves than R. ripense and may affect the flooding of river waters along the riverside.