Rupicolous communities, colonizing in particular deep cracks and ledges of calcaro-siliceous rocky slopes or cliffs, with, notably, Festuca heteropachys, Artemisia campestris, Aster linosyris, Lychnis viscaria, Potentilla rupestris. The range of these formations is centered on the Hercynian ranges of middle Germany (notably Rhine, Nahe, Moselle, Mainz valleys and Hartz periphery), extending west to Alsace and to extremely rare and isolated outposts in Ardenne valleys of Luxembourg, Belgium and France, where they are represented by Festuca heteropachys or Potentilla rupestris grasslands.