Cymbalario-Asplenion is an alliance of wall vegetation of central and western Europe, which combines species of Asplenietea trichomanis (e.g., small ferns) with diagnostic species of the Cymbalario-Parietarietea. However, the latter are mostly aliens of Mediterranean and Middle Eastern origin that are common on both rocks and walls in their primary range but are confined to walls in their secondary range in the north-west. Accompanying species include those of European or Eurasian distribution, often with a ruderal life strategy. This species composition places Cymbalario-Asplenion in a transitional position between the classes Asplenietea trichomanis and Cymbalario-Parietarietea.