Calcareous or base-rich rock faces and crevices at high altitudes of European mountain ranges in the temperate region. The chasmophytes, dwarf and cushion formed chamaephytes and hemicryptophytes, and numerous fern species and mosses, are very well adapted to the extreme habitat conditions, like strong solar radiation, a low water content, high day/night and seasonal temperature fluctuations, strong winds, and the absence of snow cover protection. The soil is in general very poorly developed, but can accumulate in crevices. Variation in the vascular flora is high across the continent and due to geographical isolation and variety in site conditions numerous relict, endemic, rare and protected species can be found on these cliffs.