These small-scale forest stands are dominated by Pinus sylvestris, frequently mixed with Quercus petraea agg. The herb layer is sparse and dominated by short acidophilous grasses and herbaceous plants typical of siliceous rock outcrops, whereas ericoid dwarf shrubs are rare. The moss layer is well developed, containing xerophilous species of mosses and lichens. This association is typical of sun-exposed rock outcrops, mainly in the deep river valleys of the Bohemian Massif. Most stands are probably primary relict pine forests, but some may have originated through human impact on dry oak forests.