I giardini storici di Perugia come biorisorsa urbana.

The aim of this study is to conduct a census and to catalogue the Historical Gardens of Perugia with the purpose to evaluate their floral composition with relation to their uses and to estimate the potential distribution of various exotic species. The analysis of the results demonstrated a remarkable variability of the examined areas, both in geographical terms and in functional ones. The soils can be divided into those ones which still belong to the pedological type (even if altered by an anthropic influence) and those plant substrata which were obtained by man through the mixture of mineral and organic materials. From the floral point of view, in most cases the exotic component is the most representative, because of the garden’s purpose, mainly ornamental. The cultivated species which grow spontaneously prevail over the non-spontaneous ones. Because of the considerable presence of highly invasive species, it seems appropriate to make a careful evaluation also in terms of green pollution and landscape transformation. It is desirable to organize a promotional activity with thematic visits to divulge the knowledge on green environment and promote the safeguard of biodiversity.