Birch Polypore (Fomitopsis betulina)

Birch Polypore (Fomitopsis betulina) – photo 3

The Birch Polypore (Fomitopsis betulina) is one of the most familiar fungi in Britain, and you will rarely walk through a birch wood without seeing it. It starts as a pale, rounded knob pushing through the bark, then grows into a smooth, kidney-shaped bracket with a pale brown to greyish-brown top, a thick rolled edge and a white underside of tiny pores. The flesh is white, tough and corky.

It grows only on birch, attacking weakened or dying trees and rotting them long after they fall, and the brackets can be seen all year. You may know it by its older name, Piptoporus betulinus, or as the Razorstrop Fungus, because its leathery skin was once used to sharpen razors. Pieces of it were even carried by Ötzi, the 5,300-year-old Iceman found in the Alps.

The Hoof Fungus (Fomes fomentarius) also grows on birch but is rock-hard, hoof-shaped and banded grey. Young Birch Polypores are not poisonous, but they are tough and bitter.

Spore Print

Season

J

F

M

A

M

J

A

S

O

N

D

Native

non-toxic

Distribution

Widespread and common everywhere

Habitat

Only found on Betula

Etymology

Fomitopsis means 'like Fomes', from the Latin fomes, 'tinder', and the Greek opsis, 'appearance'. betulina is Latin for 'of birch', after its only host.

Associates

Betula

Fruiting Body

Starts cushion-like, a rounded knob pushing out through the bark, before turning more kidney-shaped. The solitary bracket is 15-25 cm across, with a smooth, greyish-brown to pale brown upper surface, a thin skin and a rolled margin.

Cycle	Annual
Colour
Shape	Solitary bracket
Surface	Smooth
Width	15 - 25 cm

Pores

The pores are rounded to angular and small, 3-5 per mm, white to cream on the underside of the bracket. They form a fine, even surface that does not blacken when handled.