RESOLVING THE TAXONOMIC STATUS OF THE MYSTERIOUS „GREEN OAK“ (QUERCUS × VIRIDIS TRINAJSTIĆ) FROM CROATIA BASED ON PHYLOGENETIC ANALYSIS

Abstract

Te “green oak” is a well-known specifc individual oak tree of unknown origin growing near Zadar in Croatia. Depending on the authors, it was described either as a hybrid taxon between Quercus cerris L. and Q. ilex L. (named Q. × viridis Trinajstić) or alternatively as a presumed hybrid between Q. cerris and Q. suber L. To fnally resolve the origin of this taxon, we performed molecular analyses and investigated the phylogenetic relationships between the “green oak” and other closely related oak taxa from the surrounding area, including all putative parental species. A total of 16 individuals representing nine Quercus L. taxa were investigated based on both plastid (trnK-matK and trnH-psbA) and nuclear (5.8S + ITS2) DNA sequence variation. Placement of the green oak in the phylogenetic relationships between the studied oak taxa does not support Q. ilex as one of its parental species but rather indicates that this taxon is in fact Q. crenata Lam., reafrming previous alternative hypothesis that the green oak is a hybrid between Q. cerris and Q. suber. We therefore confrm the presence of Q. crenata in the Croatian flora and based on historical literature survey, we explore and discuss the implication of its occurrence and possible hybridogenic origin in the Croatian territory