A fen's a type of wetland fed by surface and/or groundwater. Fens are characterized by their water chemistry, which's neutral or alkaline. Fens are different from bogs, which are acidic, fed primarily by rainwater (ombrotrophic) and often dominated by Sphagnum mosses. Derivation The word "fen"'s derived from Old English fenn and's considered to have proto-Germanic origins, since it's cognates in Gothic (fani), Old Frisian (fenne), Dutch (veen) and German (Fenn(e), Venn, Vehn, Feen, Fehn). Fen v… (More on Fen)