The genera Diplarche and Menziesia have been shown to be nested in Rhododendron based upon cladistic analyses of DNA data. Morphologically, the differences between Diplarche and Menziesia are not so great that their inclusion in Rhododendron is inappropriate and the species of these two genera are formally transferred to Rhododendron. The following new names are proposed: Rhododendron benhallii, R. chamberlainii, R. goyozanense, R. × kamatae, R. katsumatae, R. kroniae, R. menziesii, R. menziesii subsp. glabellum, R. multiflorum, R. multiflorum forma bicolor, R. multiflorum forma brevicalyx, R. multiflorum var. purpureum, R. pentandrum, R. pilosum, R. sophistarum, R. yakushimense.