Birch polypore (fomitopsis betulina)
When it comes to foraging mushrooms the first thing most of us think about is food. The delicious umami and earthy flavours of certain mushrooms ripe for the picking in your local woodland entices many the outdoor enthusiast to learn more about the world of fungi. However, the mushroom that is the star of this article makes for terrible eating unless you enjoy tucking into a plate of polystyrene. Instead, where the birch polypore’s value lies is in its many multifaceted uses and easy identifiability to any resourceful bush crafter looking to expand their knowledge and repertoire of natural resources.
The birch polypore (Fomitopsis Betulina) also known as the birch bracket, and the razor strop mushroom is both common and abundant. The birch polypore mushroom is a parasite of birch trees, it is necrotrophic which means that is kills and feeds on the wood of the tree. The mushroom plays a crucial role in the breakdown of fallen branches and dead trees, it can be found any place that birch trees are common. This makes the mushroom both easy to find and identify.
Birch polypore are bracket fungi, a large group of mushrooms characterised by their shape and habit of growing on the side of wood and trees like shelves. The shape of this specific mushroom is reminiscent of a cockle shell sloping down from where it emerges from the tree to a flat underside, this is generally the shape the mushroom takes though it can vary greatly with sometimes a wavier edge especially when it grows large. The size of the mushroom can reach up to a foot in extreme cases but is more commonly between 10 and 20cm.
The colour of the mushroom is a light brown around the colour of a milky coffee or the crust of a farmhouse loaf excluding its underside which is an eggshell white - cream colour. Around the lip of the mushroom the surface is sometimes cracked or slightly scaly and the white underside is porous, bearing the filaments which emit the mushrooms spores. When cut into the interior is entirely white, the fibrous filaments of the underside are a slightly duller off white whilst the main flesh of the mushroom is a brighter white and the texture of rubber. When cut the mushroom does not stain which helps distinguish it from other bracket fungi such as the artist’s bracket.
So, if it can’t be eaten why is this mushroom so useful? Firstly, in truth the only reason this mushroom isn’t considered edible is because of its unappealing texture, in fact the mushroom contains several beneficial chemicals with medicinal uses. When dried the mushroom is often brewed into tea or soaked in alcohol to create tinctures. Agaric acid found in the mushroom is known to kill the parasite whipworm, it was for the medical use that the mushroom was likely used by Ötzi the iceman a 5.25-thousand-year-old mummy found in the Ötzal Alps.
Ötzi lived in the copper age of Europe and was found carrying dried birch polypore beads on a string further autopsy showed that Ötzi was suffering from a whipworm infection when he died of an unrelated injury. Birch polypore also contain the compounds which may benefit in the treatment of TB, diabetes, migraines, hypertension, convulsions, malaria, and cancer. They may also help with bacterial and viral infections including antibiotic resistant MRSA.
Whilst teas and tinctures of the mushroom may be used medicinally it can also be taken as a sort of natural multivitamin being rich in a number of essential nutrients. Other than consuming the mushroom the birch polypore holds one more application in the filed of medicine as a field dressing for wounds. If you find yourself with a small cut in the woods the white flesh of the polypore can be cut into a strip and wrapped around the cut as a makeshift plaster which dries hard keeping the cut clean of dirt whilst protecting it from infection with its antimicrobial properties and numbing the pain as a mild anaesthetic.
If this wasn’t enough there are two more practical uses of the mushroom. One is alluded to in an alternative name for Fomitopsis Betulina, razor strop mushroom. The rubbery velvet textured white flesh of the mushroom has long been used by barbers to strop their razor blades giving them a perfectly honed edge. Stropping is a method of removing rolls from a cutting edge, essentially dragging a blade across a surface and using the resistance to straighten the blades rolled edge.
The final use of the birch polypore is as a tinder for fires. When dried the mushroom can be processed to catch a spark and can hold an ember for an extended period of time allowing for fires to be transported or new sparks to be nurtured into flame. Whilst its not as effective as other mushrooms on birch like the tinder fungus or the famous chaga fungus it can make an effective fire lighting tool with minimal processing requirements.
Whilst it wont be gracing your plate any time soon perhaps the birch polypore could end up being a useful tool to you at some point, whether your camping and want a health kick or doing some wood carving and looking for a handy knife strop. So keep an eye out when you next take a walk in the woods for this charismatic mushroom with a rich history of human use.
BIBLIOGRAPHY.
1. Capasso, L., 1998. 5300 years ago, the Ice Man used natural laxatives and antibiotics. The Lancet, 352(9143), p.1864.
2. The Wildlife Trust, 2022. Birch polypore / The Wildlife Trust. The Wildlife Trust. Available at: https://www.wildlifetrusts.org/wildlife-explorer/fungi/birch-polypore. (Accessed 10/12/2022).
3. Phillips, R., Kibby, G., Foy, N. and Homola, R.L., 2005. Mushrooms and other fungi of North America (Vol. 2). Buffalo, NY: Firefly Books.
4. Roberts, P. and Evans, S., 2014. The book of fungi: a life-size guide to six hundred species from around the world. University of Chicago Press.