As its name suggests, Birch polypore fungus only grows on Birch trees. The leathery fan shaped fungus has a rounded, coffee-coloured cap that was once used for sharpening tools, hence its other name: the 'Razorstrop fungus'. The birch polypore is, as its name suggests, a bracket fungus which can be seen on many of the Birch trees on the Barff. It is rounded, smooth and leathery, and white or pale brown. It can grow up to 20cm wide and 4cm thick. It grows on ill or aging trees, eventually killing them. It can be seen in the woodland all year-round.