Taxonomic revision of Epipactis Zinn (Orchidaceae) on the Korean Peninsula.

The genus Epipactis (Orchidaceae) is widely distributed across Europe, Asia, tropical Africa, and North America. In Korea, only Epipactis thunbergii and Epipactis papillosa have traditionally been recognized, and the taxonomy of the genus has not been critically reassessed. Based on examination of protologues, herbarium specimens, and field observations, Epipactis xanthophaea, previously misidentified as E. thunbergii, is confirmed to occur in Korea and is recognized as a distinct species. Accordingly, three species of Epipactis (E. thunbergii, E. xanthophaea, and E. papillosa) are recognized on the Korean Peninsula. Their diagnostic characters and distribution ranges are clarified, and a revised taxonomic treatment is provided.