A Fen is a marsh or moor – the word in Old English is fenn: mud, dirt, moor, marsh – and the word has its origins in proto-Germanic.
The Fens are an area in eastern England; originally wetlands, much of the area was drained for use as agricultural land. Parts of the Fens are now being restored. Dye-plants like woad, weld (gaude), meadowsweet, fennel and the evocatively named purple loosestrife grow in the Fens.
Beauty product junkies who like Borghese Active Mud- fango is the Italian and Spanish word for mud, and has the same origins.
(Image: Venitian ceiling, detail. Chris Reddaway)