- where a cow can break a leg
Poor fens have a habitat with soil that is poor in both lime and nutrients. A poor fen is therefore only habitat to a few plant species.
Many areas of poor fens have a peat base which binds precipitation and retains moisture. The raised bog that is found in Vejen Mose is a special kind of poor fen that is exclusively fed by rainfall.
In particularly lime deficient and nutrient-poor areas, plants can have difficulty in obtaining nutrients through their roots. Among others, the carnivorous sundew plant grows, which captures insects in the leaves' sticky dew drops.
The plant's name alludes to the fact that animals often broke their legs when they grazed in areas with bog asphodel. In those days, it was blamed on the fact that the cows ate the plant. Today we know that it is due to calcium deficiency in poor fens.
White balls of wool
With its white wool balls, cotton grass shows up in poor fens. The tufts resemble cotton, and attempts were previously made to make yarn from cotton grass. Unfortunately, the fibres are quite short and inelastic, so it never became a success.
Threatened by overgrowth
Poor fens are threatened by overgrowth of the grass species of purple moor grass and birch and willow scrub. Grazing with cattle can be a solution, but the most swampy marshlands are hard for grazing. Burning or peeling the purple moor grass would be the most effective nature conservation in such cases.