Abstract
Species identification within the species complex of Q. pubescens is a well-known taxonomic challenge among European botanists. Some of the specific pubescent oak binomials currently accepted in various European floras and checklists were originally described in Sicily and southern Calabria. As a consequence, several species belonging to the pubescent oaks group (Q. pubescens, Q. amplifolia, Q. congesta, Q. dalechampii, Q. leptobalana and Q. virgiliana) are reported in the taxonomic and phytosociological literature. To verify whether it was possible to associate a diverse set of morphological characters with each of these different taxa, thirteen natural populations of pubescent oak from Sicily and southern Calabria were sampled. A total of 391 trees, 3,887 leaves and 1,047 fruits were collected. Overall, 28 morphological characters of oak leaves and fruits were statistically analysed using univariate and multivariate procedures. The results showed that neither the groups of morphological diversity identified by cluster analysis, nor those obtained by our expert identification through the use of analytical keys, matched with the current taxonomical frameworks as proposed by the most recent floras and checklists. Nearly all of the morphological characters considered displayed a more or less continuous trend of variation, both within and among populations. In the light of these findings it seems unlikely that more than one biological species of pubescent oak occurs in Sicily and southern Calabria.
Highlights
The majority of Southern European forest communities are characterized by the dominance of species belonging to the genus Quercus L
This was followed by the variability observed among the leaves of the tree specimens belonging to the same population (9.37%–46.73%) and by that observed among the leaves of the specimens belonging to different populations (0.83%–17.72%; Online Resource 3)
By making a pairwise comparison between the different partitions obtained by the cluster analyses on the basis of the presence of the tree specimens in the two groups and regardless of the order of the groups, an agreement always higher than 80%, was found (Online Resource 4f,g)
Summary
The majority of Southern European forest communities are characterized by the dominance of species belonging to the genus Quercus L. The genus includes about 435 species throughout the world, but this figure is probably an underestimate (Denk et al 2017). The most recent classifications based on molecular studies (Manos et al 2008; Denk and Grimm 2010; Hubert et al 2014; Denk et al 2017; Hipp et al 2019) have supported the hypothesis that the genus Quercus is divided into two monophyletic groups, which correspond to two different subgenera: subgen. Quercus, the latter composed of five sections. The European white oaks belong to the section Quercus and originated from two waves of Palaeogene radiation from north America across both the northAtlantic land bridge and the Bering land bridge (Denk et al 2017)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
