This is a community of walls and calcareous rock outcrops on dry, sunny or partially shaded sites. Its dominant species, Asplenium ruta-muraria, is well adapted to desiccation. It is accompanied by other small ferns with low cover. The most common habitats are walls containing mortar; they are usually characterized by the occurrence of slightly nitrophilous species. Natural habitats on calcareous rock outcrops contain some species of dry grasslands and Sesleria caerulea mats, while secondary stands in quarries are usually poor in species.