This association is usually dominated by Quercus petraea agg. The shrub layer is sparse and the herb layer is composed of acidotolerant, light-demanding thermophilous species, in some stands also with an admixture of species of mesic forests. A moss layer is often well developed. This vegetation occurs on south-facing slopes of poorly-weathering acidic rocks such as granite, gneiss, shale or volcanic rocks. Soils are usually shallow rankers or cambisols. In the Czech Republic this vegetation occurs mainly on volcanic hills of northern Bohemia and in deep river valleys of central and southern Bohemia and western Moravia.