In the broad concept of alliances of acidophilous oak forests that we accept here, Quercion roboris is the only alliance of the class Quercetea robori-petraeae in the Czech Republic. It includes species-poor forests of Quercus petraea agg. or Q. robur, in places mixed with Betula pendula or Pinus sylvestris on both dry and wet acidic soils. The moss layer is better developed than in most other deciduous forest types.