Birch Polypore - Fomitopsis betulina

At A Glance:

Birch Polypore - Fomitopsis betulina

Other names: Razor Strop Fungus, Piptoporus betulinus, Boletus suberosus

Season: Summer, Autumn

Edibility: Edible, Medicinal

Fungi Type: Fungi With Pores, Saprobic, Parasitic

Frequency: Very Common

Habitat: Deciduous woodland

Average width and height: w: 10 - 300mm h: 20 - 100mm

Key Features:

• Grows on birch
• Off-white to buff colour
• Smooth surface
• White to off-white underneath
• Grows horizontal

The Birch Polypore is one of my all time favourites. It has an incredibly rich and fascinating history, very beneficial medicinal properties and an array of uses. The ongoing research makes for interesting reading!

Habitat/Season

Habitat: Deciduous woodland and almost anywhere where birch trees are.

Season: Jul, Aug, Sep, Oct, Nov

As the name implies, these grow almost exclusively on on birch. They are parasitic and saprobic, so are most commonly found on dying or dead birch trees.

Whilst these can be found all year round, they have a annual growth cycle starting in summer and continuing through until late autumn. After their season, these toughen up and begin decaying. You can often see several on one tree, and sometimes with the old decaying ones from last season. See the photos!

Cap/Flesh/Fruiting Body

Average size: 10 - 300mm
Shape: ovoid, flat
Colour: off-white, light grey, browning, white underneath

The size can vary greatly, as seen in the featured image (this one measured about 30cm across!), but almost always starts very spherical and small, like a ’nub’, before maturing and flattening out. The top surface is smooth, off-white to light grey before browning a little with age, and the underside is white. The old specimens will become discoloured with all sorts and the underside will look rotten - because it is.

When cut, the flesh is white and dense, and the surface ‘skin’ can be peeled away.

Pores/Spore

Density: dense
Colour: white
Spore print: white
Spore shape: ellipsoidal, smooth

The underside is white and contains very densely packed tubes - the pores are visible only right up close. The tubes often turn a buff shade when older.

Possible Confusions

This species is in my list of top fungi for beginners because it is very easy to identify.

Edibility/Taste/Smell

These smell lovely and mushroomy, and are an edible species. The flavour has a bitterness to it and is better used dried and powdered. I’ve found the bitterness varies between each one, so I always taste a little of it after drying and before blitzing.

Medicinal Uses

There’s an awful lot of facts and info to go through and reference - stay tuned.

Notes

Etymology: Previously called Piptoporus betulinus., pipt = to fall, porus = pores, betulinus = ‘of birch trees’

Once used to strop barbers razors. As someone who believes a sharp knife is a safe knife, I can confirm using this to strop a blade really is effective.

Ötzi the Iceman - two pieces found with him. Believed to have been used for it’s medicinal properties.

References

Mushrooms and other fungi of Great Britain & Europe - Roger Phillips

Mushrooms and Toadstools of Britain and Ireland - Blacks Nature Guides