Taxonomic study of the genus Quercus L. sect. Quercus in the Zagros forests of Iran.

The genus Quercus L. (Fagaceae) is one of the most diversified groups of temperate trees with more than 500 species distributed worldwide. Quercus section Quercus, the white oaks, has the greatest number of species and has the widest distribution occurring in Asia, Europe, North Africa, and North and Central America. Oak species with lobed leaves in the Zagros forests belong to the sect. Quercus. In previous regional taxonomic accounts, Djavanchir and Menitsky identified six and two taxa of sect. Quercus in Zagros forests, respectively. We studied a great number of specimens of white oaks from the Zagros forests and assigned them to previously described taxa. Then we compared them to digital images of type specimens provided by the Royal Botanic Garden Edinburgh and National Botanic Garden of Belgium. Twenty-three qualitative and quantitative characters of leaves and acorns were examined. Cluster Analysis (CA) of data showed that morphology of leaves, micro-morphology of foliar trichomes in combination with acorn morphology are valuable in species distinction. In addition, our results showed that foliar trichomes have little value in separation of taxa at species level, whereas leaf shape proved to be a better tool for discrimination of species. According to the observations and our findings, the following taxa of white oaks with lobate leaves exist in the Zagros forests: Quercus robur L. subsp. pedunculiflora (K. Koch) Menitsky, Q. robur L. subsp. robur, Q. petraea subsp. pinnatiloba (K. Koch) Menitsky and Q. infectoria subsp. veneris (A. Kern.) Meikle. Q. robur L. subsp. robur and Q. petraea subsp. pinnatiloba (K. Koch) Menitsky are reported as new records for the flora of Iran.