Birch Polypore

A very typical looking Birch Polypore conk photographed a few days ago in the Forest of Preuilly.

Birch Polypore Fomitopsis betulina (Fr. Polypore du bouleau) is one of the many fungi that feeds off wood. Like other polypores it forms a fleshy leathery 'horse's hoof' fruiting body known as a conk. The upper surface can be white, brown or grey and is a bit suede like. The underside has fine pores with white spores. The flesh is white. It only attacks birch trees, almost always those which are old or already weakened. If you see a bracket fungus on a birch tree here it will very likely be Fomitopsis betulina. The birch trees that are attacked may have been stressed by a loss of light as other trees grow up around them, or by drought or fire. The fruiting bodies can appear singly or in groups. Nevertheless the Birch Polypore is unlikely to kill the tree very quickly, if at all ultimately. This species is much less aggressive than other polypores, but like them, it causes white rot.

 

The underside of a large conk which I found on the ground several days after first photographing it. The birch tree host had been blown over by the wind.

The fruiting body can be up to 20 cm across and 6 cm thick. It smells and tastes a bit sour. You can safely do a taste and spit test as the mushroom is not toxic, but its cork like consistency means that it is not considered edible. Detached from the tree and held in the hand they are heavier than you would expect.

 

A series of Birch Polypore conks all the way up a dying birch trunk.

Like other polypore species it has been used by humans from prehistoric times up until the 20th century as a firelighter. It has also been used to treat parasitic intestinal worms, and has anti-inflammatory and antibiotic properties. Ötzi, the 5300 year old mummy found in an Alpine glacier, was carrying Birch Polypore, possibly for its medicinal properties.

Underside.