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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, entice many outdoor enthusiasts to learn more about the world of fungi. However, the mushroom featured in this article makes for terrible eating unless you enjoy tucking into a plate of polystyrene. Instead, the birch polypore’s value lies in its many practical uses and its easy identifiability, making it a favourite among resourceful bushcrafters looking to expand their knowledge and repertoire of natural materials.
The birch polypore (Fomitopsis betulina), also known as the birch bracket or razor strop mushroom, is both common and abundant. It is a parasite of birch trees and is necrotrophic, meaning it kills and feeds on the tree's wood. The mushroom plays a crucial role in breaking down fallen branches and dead trunks and can be found wherever birch trees are prevalent. This makes it both easy to locate and simple to identify.
Birch polypores are bracket fungi, a large group of mushrooms characterised by their shelf-like growth on the sides of trees and wood. The shape of this particular mushroom resembles a cockle shell, sloping down from where it emerges from the tree to a flat underside. This is its typical form, though it can vary, sometimes developing a wavier edge, especially when it grows large. The mushroom can reach up to a foot across in extreme cases, but more commonly measures between 10 and 20 centimetres.
Its colour is a light brown, similar to milky coffee or the crust of a farmhouse loaf, excluding the underside, which is an eggshell white to cream shade. Around the lip, the surface is sometimes cracked or slightly scaly, and the white underside is porous, bearing the filaments that release the mushroom’s spores. When sliced open, the interior is entirely white. The fibrous filaments of the underside are a slightly duller off-white, while the main flesh is a brighter white with a rubbery texture. Notably, the mushroom does not stain when cut, which helps distinguish it from other bracket fungi such as the artist’s bracket.
So, if it cannot be eaten, why is this mushroom so useful? In truth, the only reason it is not considered edible is its unappealing texture. In fact, the mushroom contains several beneficial chemicals with medicinal properties. When dried, it 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 likely for this medicinal use that Ötzi the Iceman, a 5,250-year-old mummy found in the Ötztal Alps, carried the mushroom.
Ötzi lived during the Copper Age in Europe and was found with dried birch polypore beads strung together around his neck. Further autopsy revealed that he was suffering from a whipworm infection at the time of his death, which was caused by an unrelated injury. Birch polypore also contains compounds that may be beneficial in the treatment of tuberculosis, diabetes, migraines, hypertension, convulsions, malaria, and cancer. It may also help with bacterial and viral infections, including antibiotic-resistant MRSA.
While teas and tinctures made from the mushroom may be used medicinally, it can also be taken as a kind of natural multivitamin, being rich in a number of essential nutrients. Beyond consumption, birch polypore has another application in medicine as a wound dressing. If you find yourself with a small cut in the woods, the white flesh of the polypore can be sliced into a strip and wrapped around the wound as a makeshift plaster. It dries hard, keeping the cut clean and protected from dirt, while its antimicrobial properties help prevent infection, and its mild anaesthetic effect numbs the pain.
If that were not enough, there are two more practical uses for the mushroom. One is hinted at in one of its alternative names, razor strop mushroom. The rubbery, velvet-textured white flesh 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 blade’s rolled edge.
The final use of birch polypore is as tinder for fires. When dried, the mushroom can be processed to catch a spark and hold an ember for an extended period, allowing fires to be transported or new sparks to be nurtured into flame. While it is not as effective as other birch-associated fungi, such as tinder fungus or the famous chaga, it can still serve as an efficient fire-lighting tool with minimal processing.
Although it will not be gracing your plate any time soon, the birch polypore could prove useful, whether you are camping and want a health boost or carving wood and need a handy knife strop. So, keep an eye out next time you take a walk in the woods for this charismatic mushroom with a rich history of human use.
BIBLIOGRAPHY.
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.
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