The Castanea which belong to the Fagaceae or Copuliferae family which also contains Lithocarpus, Northofagus and Quercus was nominated in 1753 by Carl Nilsson Linneaus as Fagus Castanea, this emphasizing the beech relationship. In 1768 Philip Miller interpreted the tree as an independent genus reclassifying it with the current binomial. The genus with its species has spread over three main areas, represented by Europe and the Mediterranean countries, Asia and North America. Present chestnut biodiversity displays a high genetic variability, due to its adaptation capacity to quite different pedoclimatic conditions. In Europe, Castanea sativa Mill. diffusion is attributable to both its adaptation capacity and man’s intervention and especially to the work of Roman and Greek civilizations and to monastic orders during the Middle Ages. The overlapping of these elements has made reconstruction of genus origin and diffusion quite difficult and has originated a large number of forms difficult to characterize. The intuitive process according to which the selected plants were characterised according to their most conspicuous features, by utilizing the so called “vernacular” names, further contributed to increase synonyms and therefore varietal confusion. For the characterization of the cultivated varieties of Castanea sativa Mill. two main methods have been utilized; the morphological method was started as back as the XVII century, while the molecular techniques have been adopted of the beginning of the XXI century. Recent genetic developments and use of molecular markers has further helped to clarify and develop models of species diffusion and to understand the effects of man’s intervention. In this review is presented the state of the art of traditional and molecular chestnut varietal classification, with emphasis on its limits and peculiarities by comparing research methodologies and results obtained. A classification history and different approaches to varietal characterisation during centuries emerged from this analysis. The earliest classification were mostly based on mainly botanical characters; later agronomical characters were included, with the aim of distinguishing an individual from another in the same species as agricultural varieties. By the beginning of 2000 it was possible to introduce the molecular characterisation which has dramatically increased the potential in both varietal classification and in the studies on the genus origin. Scientists today agree on the assumption that the combination of morphological and molecular techniques is essential for a proper and complete characterisation of chestnut germplasm.
Keywords: European chestnut, chestnut descriptors, morphological characterization, molecular markers, SSR markers