The alliance Geranion sanguinei includes thermophilous herbaceous vegetation dominated by broad-leaved herbs in which species of dry grasslands and of the understorey of open oak forests grow together. This vegetation is mostly found in ecotonal situations where dry grasslands border thermophilous oak forests or xeric shrub vegetation; it may also develop from a dry grassland after abandonment. It may be either a part of natural zonation in forest-steppe vegetation complexes or vegetation developed in human-created ecotones. The Geranion sanguinei fringe vegetation is mainly found in warm areas of northern, central and eastern Bohemia and southern Moravia.