The Vascular Flora of Italian Volcanic Lake Calderas: A Comprehensive Floristic Study

A comprehensive floristic study on the vascular flora of the 11 Italian volcanic lake calderas is presented. Despite encompassing one of the Mediterranean’s major freshwater systems, floristic research in these areas has proved fragmented and often outdated. By integrating literature data with original data from new floristic surveys, a total of 1182 spontaneous plant taxa were recorded, including 152 alien plants. Six taxa represent regional novelties and 102 are new for the study area, while 48 taxa reported before 1950 were not confirmed locally. From a conservation perspective, 27 taxa of national interest were reported, including two species classified as Critically Endangered (Isoëtes sabatina, Vicia incisa) and four Endangered (Carex vulpina, Baldellia ranunculoides, Hippuris vulgaris, Hydrocotyle vulgaris) according to IUCN criteria, along with 50 taxa listed on regional red lists. Floristic richness varies notably, from 124 taxa in the caldera of Lake Giulianello to 756 in Lake Bracciano, reflecting differences in caldera size, degree of anthropogenic impact and availability of previous botanical data. These results significantly enrich the floristic knowledge of the calderas of Italian volcanic lakes and may represent a solid reference for future naturalistic research in these areas.