Home / Polypores, brackets & crusts / TM0062
Birch polypore
Fomitopsis betulina or Fomes fomentarius Genus
Angles captured. Three frames of the brackets on the log, then two showing the underside — the frames that make the identification.
Morphology
Two hoof-like to kidney-shaped brackets, 10–15 cm across, thick and firmly rubbery. Upper surface smooth, pale grey-buff, finely cracked, with a blunt inrolled margin. The underside is a startling matte black against a pale rim — a dark, finely pored surface set within the incurved white margin.
Habitat & substrate
On a fallen paper birch, growing directly from the trunk. Host-specific.
Lookalikes & what rules them out
Two birch classics collide here. Fomitopsis betulina is annual: kidney-shaped, smooth grey-brown above, pale rubbery flesh, pores white browning with age. Fomes fomentarius is perennial: hoof-shaped, grey, hard-crusted and cracked, with grey-brown pores. These brackets are thick, rounded and deeply crazed, and the pore surface is dark — several characters leaning Fomes.
To confirm this identification
Section one bracket top to bottom. Stacked tube layers = Fomes fomentarius; a single tube layer over pale rubbery flesh = Fomitopsis betulina.
Notes
One of only two species-level identifications in this volume, and it is the underside frames that earned it. The black pore surface is unusual enough to be worth returning to. Corrected. Published at High with nothing to confirm, while the same entry flagged the black pore surface as unusual. Those two statements could not both stand; the anomaly was evidence, and it now has the identification in question.
Found at Elm St area, Leominster, MA on Thursday, 6 August 2026 at 12:02. See the full walk for that day's weather and everything else recorded.
Others in this group
Perennial polypore on an oak trunkGanoderma sp. · Oct 10Moderate
Small zoned bracketTrametes or Stereum · Jul 31Moderate
Cinnabar polypore on oakPycnoporus cinnabarinus (= Trametes cinnabarina) · Aug 1High
Zoned brackets on rockTrametes or Stereum · Aug 6Moderate
Cinnabar polypore on a stickPycnoporus cinnabarinus (= Trametes cinnabarina) · Aug 6High
Bracket colony among fernsTrametes or Stereum · Aug 8Low–moderate
Turkey tail on the fallen logTrametes versicolor · Aug 8Moderate–high
Bracket colony on the rock ledgeTrametes or Stereum · Aug 8Low–moderate