Preliminary Study on Taxonomic Review Using Histological Sections of Some Iberian Species from the Genus <i>Quercus</i> L. (Fagaceae)

Abstract

The taxonomy of the genus Quercus is the subject of ongoing scientific interest at the present time. Classically the scanning electron microscope is and has been used for the study of leaf surfaces, particularly to characterise the trichomes, stomata and epicuticular waxes. In the present work, in addition to using the SEM, histological sections from a group of taxa from the northern Iberian Peninsula are studied under the optical microscope. Specifically, the study concerns the leaves of Quercus robur subsp. robur , Q. orocantabrica , Q. petraea and Q. pyrenaica , and of possible hybrids between Q. orocantabrica and Q. petraea and between Q. orocantabrica and Q. pyrenaica . The results highlight histological differences between Q. robur and Q. orocantabrica , and also differentiate the morphological characteristics of Q. petraea and Q. pyrenaica . Similarities can also be observed between Q. petraea and its possible hybrid with Q. orocantabrica , and between Q. pyrenaica and its hybrid with Q. orocantabrica . The aspects observed under the optical microscope complement the observations obtained by means of the scanning electron microscope, and as a consequence of this, two new nothospecies are described: Q. xpuentei ( Q. orocantabrica × Q. petraea ) and Q. xpenasii ( Q. orocantabrica × Q. pyrenaica ).