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  • Writer's pictureTom Holley

13 | Photographing Mushrooms: 08 - Birch Polypore // Fomitopsis Betulina

Number 08 - Formitopsis Betulina otherwise known as the Polypore Birch fungus which primarily grows on Birch trees. This a fleshy bracket fungus spawning annually on living/dying & dead hosts as a parasite & saprobe which is widespread in the northern hemisphere. The Formitopsis is a genus of over 40 species of bracket fungi in the Fomitopsidaceae family; belonging to the antrodia clade, containing around70% brown-rot fungi. My pictures were taken from a few of the 46 different specimens, so please note can differ in appearance to what you may find/ stage of life.


Cap: Close to spherical in immaturity, but develops a "kidney" or semi-circular shape in maturity as they begin to flatten (see figure 01). Glabrous when young, margin inrolled/round on upper surface (see figure 02). Can be very misinterpreted in young age; & doesn't reflect the typical birch polypore in, say a fully matured. Underside reflects darker colours as it's progresses throughout it's life, particualrly working inward from under the margin on the pores. Atop the cap, generally whiteish-pale grey turning "coffee" to a brownish look. Green is very apparent when aged, 3 specimens I find all had varying greenish coverings were had all recently died so this is evident.



(Figure 01) Kidney/Semi-circular shaped body develops by maturity

(Figure 02) Inrolled margin

Spores/Print: White from early life into maturity developing very fine white pores (3-4 per 1mm - see figure 03). Yellow-brownish in age. Depressed from margin. Young specimens may lack spores, pore layer not yet formed. Cylindrical to ellipsoidal; 4-6 x 1.3-2μm; smooth. Release spores in late summer/early autumn.



(Figure 03) Pores

Stipe: No real stem. If present are quite lateral. (see figures 04 & 05)



(Figure 04) Lateral stipe's can be present; see figure 05

(Figure 05) No stipe present on specimen/host

Flesh: Firm/white


Skirt: Absent/ N.A


Size/Height: Cap: 6-30cm diameter/Width: 8cm. Stem: N/A


Season: All year; these fungus' can live for up to a year, which is why they are known to eventually grind it's host down to death. I witnessed 46 specimens living on 7 branches/trunks, they will simply replace the fruiting with another inc. living on dead wood.


Habitat/Ecological role: Birch Trees. Can live in living or dead wood; particularly dying Birch, you will often see snapped trunks or branches as a result. All specimens I personally photographed were on Silver Birches (Betula Pendula). They are parasitic fungi when on a living host; as it is not a mutualistic relationship. Once on dead wood become a saprobe & so therefore is able to grow annually until it's host has rotted.



Macroscape


Distribution: Can be solely however can be seen pictured imitating steps up a trunk; with the matured shelf appearance. So can appear in quite vigorous numbers.


Edible: Yes! Take with a pinch of salt, because it depends on the bearer of the mushroom, you read or hear from different people differing views, so it's really a personal preference. Taste/Odour: Very mushroomy taste but can be bitter specially in matured. Said that younger specimens are nicer as tender/odour: mushroomy.


Medicinal: Anti-Inflammatory, consumed as a tea or eaten (fried), young specimens are said to taste nice as tender too, older quite bitter. I guess the positive is as they are seen all year, & grow in large numbers, you can obviously experiment. Has other huge purposes such Anti-viral, Antibiotic, Anti-septic & many more! Check this link for more information: https://whisperingearth.co.uk/2015/02/15/birch-polypore-medicine-ancient-and-modern/


Confusion Species: I have to say, not many mushrooms lack a confusion considering the high number of, however the Fomitopsis Betulina grows restricted singly to Birch trees & specific colouring especially in maturity is difficult to confuse.


Etymology: The synonym of which Piptoporus Betulinus, the former pipt to "fall" easily detached because of the eventual size; therefore weight, & porus meaning "pores." Betulinas on the otherhand is the specific epithet "of Birch Trees."


Other Notes: As well as medicinal purposes dating some 5300 years ago, the Formitopsis Betulina is also known as a Razor Strop fungus, as people were known to sharpen there knives with these mushrooms.


Pictures taken: 21st January / 23rd January 2022


Reference List:

Mushroom Pocket Guide



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