Reappraisal ofDiplolabellum coreanum (orchidaceae) as inferred from molecular data

The taxonomic treatment of a monotypic genus, Diplolabellum , has been disputed by various authors. Maekawa (1935) described the genus on the basis of Oreorchis coreana IFinet. Because distribution of its plants is very limited, i.e., to Jeju Island of the South Korean Peninsula, it has not been well studied. To reappraise the phylogenetic relationship of Diplolabellum coreanum Finet, we obtained ITS, matK, trnT-trnL , and trnL-trnF sequences from several species of Oreorchis and related genera. Sequence analysis showed that D. coreanum is closely related to one group of Oreorchis that consists of O. patens Lindle and O. fargesii Finet. Therefore, our molecular data support treating the species as O. coreana rather than as D. coreanum , even though the latter genus is distinct from Oreorchis in morphological characters such as callus, pedicel, column, and caudicle.