Fens — a specific type of wetland — are one of the more unusual habitats in Iowa, with roughly 300 known fens scattered throughout the state.
At first sight, a fen resembles that part of the pasture that is perpetually flooded and well-loved. Water soaked ground, the grasses and flowers present in fens are concentrated in sporadic earthy mounds surrounded by puddles of water.
Found mostly in northwest and north central Iowa and fed by groundwater, instead of rain or other sources.
Unevenly rising hummocky mounds of dirt are a classic characteristic of a fen landscape, and can be bouncy, giving the feeling of walking on a waterbed. The water chemistry of fens is special, limiting the occurrence of certain plants while others flourish and can be found only in a fen environment.
Iowa Natural Heritage Foundation