Abstract. Delforge, P. - Contribution to the knowledge of the Orchids of Croatia. Results of five years of prospecting [Natural. belges 87 (Orchid. 19) (2006): 141-200]. Research in Croatia in May and June 2002, April 2003, March, April, May, and June 2004, July 2005, and July 2006, sometimes in collaboration with local specialists, has revealed 80 species and 27 interspecific hybrids. After a short presentation of the past and present studies about Croatian orchids, discussions are made for critical and most interesting taxa observed. Epipactis helleborine var. orbicularis (K. Richter) Vermeulen (non E. distans Arvet-Touvet) has been found in the Plitvicka Jezera Nacionalni Park (County of Zadar, near the Bosnian border), as well as E. leptochila var. dinarica and E. leptochila var. neglecta. E. pseudopurpurata, mentioned in this area, is identified here with E. purpurata; consequently, E. pseudopurpurata does not belong to the Croatian flora. The presence of E. exilis, E. greuteri, E. leptochila var. leptochila, E. leptochila var. neglecta, E. muelleri, E. purpurata, E. rivularis is confirmed for the Mt. Medvednica (Central Croatia, Zagreb), that of E. placentina for the region of Sinj, Central Dalmatia. Epipactis brestina Kranjcev nom. nud., Epipactis istriaca Kranjcev nom. nud., Epipactis luteoviridis Kranjcev nom. nud. appear to be synonyms of E. muelleri, Epipactis zagrabiensis Kranjcev nom. nud., synonym of E. exilis. In the genus Ophrys, the presence in Southern Dalmatia of Ophrys neglecta, generally mentioned as O. tenthredinifera, is confirmed and, consequently, O. tenthredinifera does not belong to the Croatian flora. The presence of O. untchjii and O. tetraloniae is confirmed in Central Dalmatia where the latter has been mentionned also as O. annae, O. gracilis or O. serotina, species that do not belong to the Croatian flora. O. liburnica is a well delimited species of the O.exaltata species group; it is widely distributed from Istria to Dubrovnik and on the islands; it is frequently mistaken for O. sphegodes, O. classica or O. archipelagi; O. classica does not belong to the Croatian flora. Hybrids of O. liburnica with different species of the O. sphegodes species complex are rather frequent. They are diversely identified, sometimes to species that do not belong to the Croatian flora, as O. amanensis, O. arachnitiformis, O. biscutella, O. brutia, O. cephalonica, O. cilentana, O. epirotica, O. herae, O. montis-leonis, O. panormitana, O. passionis, and O. spruneri. They have been also recently published under various invalid names. As a result, Epipactis brestina Kranjcev nom. nud., Epipactis istriaca Kranjcev nom. nud., Epipactis luteoviridis Kranjcev nom. nud., Epipactis pseudopurpurata, Epipactis zagrabiensis Kranjcev nom. nud., Ophrys amanensis, Ophrys annae, Ophrys arachnitiformis, Ophrys biscutella, Ophrys blacatina Kranjcev nom. nud., Ophrys brutia, Ophrys cattaniae Kranjcev nom. nud., Ophrys cephalonica, Ophrys cilentana, Ophrys classica, Ophrys classica subsp. lastobona Kranjcev nom. nud., Ophrys croatica Kranjcev nom. nud., Ophrys dalmatina Kranjcev nom. nud., Ophrys epirotica, Ophrys gracilis, Ophrys herae, Ophrys horvati Kranjcev nom. nud., Ophrys korculana Kranjcev nom. nud., Ophrys largopetala Kranjcev nom. nud., Ophrys montis-leonis, Ophrys panormitana, Ophrys passionis, Ophrys serotina, Ophrys pseudohittitica Kranjcev nom. nud., Ophrys rilicica Kranjcev nom. nud., Ophrys salotinica Kranjcev nom. nud., Ophrys scolopax, Ophrys spalatina Kranjcev nom. nud., Ophrys sphegodes subsp. adamovici Kranjcev nom. nud., Ophrys spruneri, and Ophrys tenthredinifera would be deleted from the list of the Orchidaceae of the Flora Croatica. A detailed list of the 80 species, 27 interspecific hybrids, and 536 localities prospected as well as 4 distribution maps are provided.

Key-Words. Orchidaceae; flora of Croatia.