This association, dominated by Carex rostrata in the herb layer and Warnstorfia fluitans in the moss layer, occurs in hollows at bog margins (laggs) and on shallow peat. It represents an initial phase of bog development. Water is very acidic and poor in minerals and nutrients. Shallow peat supports the growth of some mineral-demanding species such as Carex rostrata, which root below the peat in the mineral bedrock. This association has been recorded in the Jizerské hory, Krkonoše, Králický Sněžník and Hrubý Jeseník Mountains.