This marsh type is dominated by the tall grass Calamagrostis canescens. It occurs on both mineral and peaty soils in reed vegetation zones around fishponds and in wet meadow and mire complexes. It is inundated for short periods by water up to 20 cm deep. On the shores of fishponds it usually occurs between the zone of tall sedges and adjacent non-flooded areas. Stands of C. canescens may occur naturally as advanced stages of the terrestrialization processes, but they may also develop on drained peatlands. This association is most common in the basins of southern Bohemia, but it also occurs elsewhere in lowland to submontane areas of the Czech Republic.