Abstract. Claessens, J. & Kleynen, J.- Some thoughts about polymorphy in the genus Epipactis [Natural. belges 80 (Orchid. 12) (1999): 333-342]. The genus Epipactis is wellknown for its polymorphism. In this paper the authors give examples to illustrate the great plasticity of the genus. In their view polymorphism is inextricably bound up with most representants of the genus Epipactis, a fact that should be taken into consideration before describing new ĮspeciesČ. Starting from this assumption, the authors come to several conclusions. After having studied many populations of small-leaved E. helleborine, they conclude that those populations represent ecotypes of E. helleborine. In many cases the normal form of E. helleborine grew nearby. Therefore all ecotypes should be regarded as subspecies, thus following Klein's concept of E. helleborine subsp. orbicularis. After having studied E. leutei for several years, the authors come to the conclusion that there are no significant differences between E. helleborine and E. leutei; therefore E. leutei is regarded as being a synonyme of E. helleborine. The morphology of the column and the mode of pollination are not absolute discriminative characters, since transitional forms can often be found. Deviant forms, like those showing the presence of a viscidium in E. albensis, are discussed, but they are considered to fall within the variability of the species. As a consequence E. mecsekensis is regarded as a synonyme of E. albensis, and E. flaminia as a synonyme of E. greuteri. E. confusa has always provided much confusion, the cause of which is discussed. Recent Danish research shows that E. phyllanthes and E. confusa are conspecific, the name E. phyllanthes having priority. Due to an unlucky choice of the type specimen, there has long been much confusion about the true nature of E. leptochila. Nowadays there exists a great number of publications illustrating the polymorphy of this species. The recently described E. komoricensis represents probably one of the many variations of E. leptochila.
Key-Words: Epipactis, E. helleborine subsp. orbicularis, E. albensis, E. greuteri, E. flaminia, E. leutei, E. mecsekensis, E. phyllanthes, E. confusa, E. leptochila, E. komoricensis.