What You Should Know
Polyporus brumalis is a small, dark brown polypore that distinguishes itself from similar species by having a stem that does not become black, a smooth (rather than hairy) cap margin, and tiny circular pores. It fruits on the deadwood of hardwoods and has a special affinity for birch. The tough fruiting bodies are persistent and can be found year-round, but it tends to come up fresh in fall and spring.
The pores of these thin-capped polypores cannot be detached from the upper layer of the cap.
Other names: Winter Polypore.
Polyporus brumalis Mushroom Identification
Saprobic on decaying wood of hardwoods and especially frequent on dead birch wood; growing alone or gregariously; fall and spring, but found nearly year-round; widely distributed in North America.
2–8 cm; broadly convex with a tucked-under margin at first; becoming flat, or shallowly depressed; round in outline; dry; bald or very finely hairy; dark yellowish-brown to dark brown.
Running slightly down the stem; white; not bruising; with 2–3 round pores per mm; tubes to 3 mm deep.
Central or somewhat off-center; 2–4 cm long; 2–5 mm wide; equal; dry; bald or finely hairy; whitish to grayish or pale brownish; tough.
Whitish; thin; very tough.
Spores 6–7 x 1–1.5 µm; cylindric; smooth; hyaline in KOH. Hymenial cystidia not found. Hyphal system dimitic. Clamp connections are present.
Polyporus ciliatus is very similar but has much smaller, more densely packed pores.
Polyporus brumalis Health Benefits
An extract of culture mycelia was able to inhibit the growth of Sarcoma 180 solid cancer in mice by 90% (Ohtsuka et al., 1973).
Using the streak-plate method (a test for antibacterial activity), this species did not inhibit the growth of Staphylococcus aureus nor Escherichia coli on either thiamine peptone medium or malt agar (Robbins et al., 1945).
Polyporus brumalis Taxonomy and Etymology
The Winter Polypore was described scientifically in 1794 by Christiaan Hendrik Persoon, who created its basionym when he gave it the scientific binomial name Boletus brumalis.
In 1821 the Swedish mycologist Elias Magnus Fries transferred this species to its current genus, at which point its currently-accepted scientific name Polyporus brumalis was established.
Synonyms of Polyporus brumalis include Boletus fuscidulus Schrad., Boletus brumalis Pers., and Polyporus fuscidulus Schrad.) Fr., Lentinus brumalis (Pers.) Zmitr.
The generic name Polyporus means 'having many pores', and fungi in this genus do indeed have tubes terminating in pores rather than gills or any other kind of hymenial surface.
The specific epithet brumalis means 'of winter' and is another reference to the emergence of this species mainly in the cooler months of the year.
The fruitbodies of this tough little polypore are very slow to rot. As a result, you can expect to find Winter Polypores all through summer, albeit with darkened pore surfaces and no longer producing spores.
Polyporus brumalis Video
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