Piptoporus betulinus

Scientific name:   Piptoporus betulinus (Bull.: Fr.) Karst
Derivation of name:   Piptoporus means "a polypore that
falls off"; betulinus means "inhabiting birch (Betula) trees."
Synonymy:   Polyporus betulinus Bull.: Fr.
Common names: Birch polypore. 
Phylum:   Basidiomycota
Order:   Polyporales
Family:   Fomitopsidaceae
Occurrence on wood substrate:  Parasitic and saprobic;
solitary or grouped on living or dead birch (Betula spp.) trees,
also on stumps and logs; year-round. 
Dimensions:  Caps 2.5-25 cm wide and 1-7.5 cm thick;
stipes (if present) are lateral, thick and up to 6 cm long.  
Upper surface: Whitish to pale gray-brown with darker
brown streaks; smooth and glabrous when young; margin
rounded and inrolled.
Pore surface: White at first, yellowish-brown in age;
depressed from the margin; pores 3-4 per mm..
Edibility: Apparently edible when young and tender and not
too bitter.
Comments: At the following website read about Oetzi, the
5000 year old "Ice man." He had among his possessions
pieces of this fungus which might have been used for
medicinal purposes.

More information at MushroomExpert.com:

Figure 1. Fruitbodies of Piptoporus betulinus growing from
a birch tree in New Hampshire. Photo © Gary Emberger.


Figure 2. Sooner or later, standing trees parasitized or
decomposed by the birch polypore will start to fall apart.
Photo © Gary Emberger.

Figure 3. Lateral stipe, smooth and hairless cap of the birch
polypore. Photo © Gary Emberger.

Figure 4. A collection of Piptoporus betulinus found
during the 2003 North American Mycological Association
meetings at Campus Notre Dame de Foy, Saint-Augustin
de DesMaures, Canada in 2003. The species is reported
to reach its best development in cooler climates. Photo ©
Gary Emberger.

Figure 5. Young specimens such as this one may appear
to lack pores. It's not that the pores are too small to see
but rather that the pore layer has not yet formed.
Photo © Gary Emberger.

Figure 6. The thick, rounded and inrolled margin of the
birch polypore is distinctive. It projects downward beyond
the level of the pore surface resulting in the pore surface
appearing sunken or depressed. Photo © Gary Emberger.


Figure 7. This particularly large specimen is about 25 cm
wide. Its single point of attachment to the substrate is visible
right above cm markings 10-15. Photo © Gary Emberger.


Figure 8. The top surface of the specimen shown in Figure 5.
Photo © Gary Emberger.