engleski

Investigation of an oak of unknown origin

An unusual oak of unknown origin growing near Zadar, Croatia is called the Green oak. This tree produces hermaphroditic flowers and flowering is not synchronized with other oaks in the vicinity. The tree has been classified as a putative hybrid between Quercus cerris L. and Q. ilex L., Quercus viridis Trinajstić. However, this classification is probably not accurate, as a hybrid between a species where acorns mature in the second year (Q. cerris) and a species where acorns mature in the first year (Q. ilex) has never been verified. To investigate the origin and taxonomic position of this tree, we conducted comparative investigations in wood and leaf anatomy and morphology of flowers and pollen among the Green oak and specimens of Q. cerris, and Q. ilex using a light microscope combined with digital image analysis and a scanning electron microscopy. The hairs of all three oak species were examined using several histochemical reactions and scanning electrom microscopy, and the DNA content of nuclei was measured. Volatile compounds of the leaves were determined using gas chromatography. The results of these investigations, and the origin of the green oak are discussed.

Quercus; hermaphroditic flowers; hybrid; wood anatomy; leaf anatomy

nije evidentirano