Abstract
The conservation actions of endangered plant species require a clear knowledge of their habitats. Urtica rupestris Guss. (Urticaceae) is a rare endemic plant species occurring on shady cliffs in the southern-eastern part of Sicily. In the last century, the extreme anthropogenic alterations of Hyblaean plateau have caused the continuous and unrestrained fragmentation of natural habitats and consequently the reduction and disappearance of some plant species. A total of 52 vegetation plots, of which 34 are unpublished, were analyzed in order to characterize the floristic composition of the U. rupestris community. All the relevés were classified using classification and ordination methods. The species is mainly linked to shady and wet rock habitats, and only secondarily colonizes the undergrowth shrubs. According to IUCN criteria, we propose a new risk status for this species and the establishment of a new habitat (92/43CEE) for correct long-term conservation. Finally, a new association, Urtico rupestris-Adiantetum capilli-veneris, which falls within the Polysticho setiferi-Phyllitidion scolopendrii alliance (Adiantetea capilli-veneris class), was described. This study can provide useful information for the management and conservation of U. rupestris.