Fomitopsis betulina

September 20, 2021

Good evening friends,

This week’s mushroom is Fomitopsis betulina, formerly known as Piptoporous betulinus and commonly known as the Birch polypore. This was a fun find last Thursday; not only had I not seen this mushroom in the park before, but this is also just the second sighting of it in Manhattan per iNaturalist. The only reason I found this mushroom was because we were on a rowboat removing trash and fishing line from the banks of the 59th St Pond when we came upon two fallen gray birch trees (Betula populifolia) that were only accessible from the water. The pictures aren’t great since I took them while standing in a rowboat (and my phone’s camera already leaves quite a bit to be desired when I have both feet on the ground). I could write all day about this mushroom but for the sake of brevity I’ll try to keep it reasonable.


F. betulina grows spring through fall and the conks (another term for the fruiting body) can be found on the tree year-round. It is found wherever birch trees are found (predominantly North America, Europe, and Asia) and grows exclusively on birches. It is saprobic (consumes the dead organic material) on birches and is also thought to be parasitic in instances when the tree becomes weakened by drought, disease, fire, or other natural causes. It is a brown rot fungus which means it prefers to consume the cellulose in the plant cell walls. Saprobic fungi can be classified as either brown rot or white rot fungi depending on which of the major components of the plant cell walls (the lignin or the cellulose) they’re more inclined to consume. Brown rot fungi have an appetite for cellulose and don’t care much for the lignin while white rot fungi have a hankering for lignin and are not as inclined to the cellulose. We have covered these distinctions before but I still have trouble remembering brown rot = cellulose chewer and white rot = lignin lover.

Fun Facts

Ötzi the Iceman is a mummified human found in the Ötztal Alps (between Austria and Italy) that lived ~5,300 years ago. His body was well preserved (he died from an arrow injury to his shoulder so it’s suspected that he was murdered) and all of his possessions were also intact. Among his possessions were two mushrooms, one of which was – you guessed it – Fomitopsis betulina. It’s suspected that he used this mushroom to fight off parasitic worms found in his intestines. The mushroom contains agaric acid, a strong purgative, which he probably used to help rid himself of the worms. The mushroom also contains resins and antimicrobial compounds which could’ve acted against the worms directly as a more localized treatment to complement the general purgative properties.

Medicinal Properties

As previously touched on, this mushroom contains a variety of anti-inflammatory, anti-carcinogenic, immune-boosting, and pro-digestive properties. Since we know Ötzi possessed the mushroom, we can say that it is one of humanity’s longest used medicinal mushrooms. One compound in the mushroom is betulinic acid, obtained from the birch tree, which is known to create apoptosis (cell death) in cancer cells. A topical application of this mushroom is to simply use it as a natural bandage to stop bleeding and ward off infection – another use that could’ve been employed by Ötzi. The mushroom can be consumed in teas, tinctures, or extracts. There are a variety of benefits to some of the researched compounds in this mushroom and if you’re curious you can learn more in the 4th, 5th, and 6th references.

One last note: While this mushroom had not been seen to this point in Central Park, per iNaturalist and Gary Lincoff’s website (, we have been planting birches in the natural areas quite heavily over the past few years so I only anticipate this mushroom to become more prevalent.

There’s a full moon tonight and the equinox is on Wednesday,

General References

Otzi References