Contribution to the vascular flora of the Castelli Romani Regional Park (Rome, Central Italy) with recent observations and early herbarium surveys

We report the results of a floristic survey carried out in the Castelli Romani Regional Park (Rome, Central Italy) during the years 2003-2008, supplemented with data derived from recent literature. The Park includes part of Colli Albani, four SCIs and a SPA. The purpose of this study was to assess the actual floristic value of an area close to the city of Rome, yet still at medium floristic knowledge. The area has peculiar features in terms of lithomorphology (volcanic rocks, volcanic lakes), soils (andisoils, brown soils), and phytoclimate (Mediterranean Transitional Region, Temperate Region). The floristic list is composed of 796 units belonging to 783 species, 420 genera, and 102 families. One species, Sechium edule (Jacq.) Sw., is new to Lazio Region. The woody flora reaches 12.06%, while, as for the herbaceous flora, Hemicryptophytes slightly prevail over Therophytes. As regards chorotypes, together with a considerable number of Mediterranean s. l. and of European species, there are many species with wide distribution area, testifying a longlasting and deep urban impact which started many decades ago. The flora of the Park is similar enough, both in structural and geographical terms, to the flora of the volcanic district of Vico (northern Lazio Region); a detailed comparison concerning aquatic and hygrophilous flora between the two areas pointed out similar sets of rhizophyte species, whereas in the lakes of Albano and Nemi helophyte belt and wet meadows are lacking. Quite few species that are rare or extremely rare to Lazio Region or included in the Regional Red Lists of the Italian Plants were recorded. Nevertheless, some of them have a high biogeographical value (e.g., Vicia sativa subsp. incisa, Adenocarpus samniticus) or are typical of rare environments (Potamogeton sp. pl.). A test study limited to Lycopodiophyta, Ferns and allies, and Orchidaceae was carried out on ancient herbarium specimens kept in the Herbarium RO, showing that 21 units are today no longer recorded.