Bondarzewia berkeleyi

Scientific name:   Bondarzewia berkeleyi (Fr.) Bond.
& Sing.
Derivation of name:   Bondarzewia is named for A.S.
Bondarzew; berkeleyi is named for British mycologist
M. J. Berkeley (1803-1889).
Synonymy:  Polyporus berkeleyi Fr.
Common names:   Berkeley's polypore.
Phylum:   Basidiomycota
Order:   Russulales
Family:   Bondarzewiaceae
Occurrence on wood substrate: Parasitic and saprophytic;
at the base of oaks and other living deciduous trees,  around
decaying stumps or from buried roots; July through October.
Dimensions:  The entire rosette of overlapping caps may be
a meter or more across. 
Upper surface:  Creamy white to yellowish to tan,
somewhat zonate; dry; hairy or not.      
Pore surface: Whitish, becoming dingy; pores large (0.5-2
mm), portions of the pore surface may appear maze-like.
Edibility: Edible when young, bitter with age.
Comments: Berkeley's polypore causes a butt rot of living
trees. When young, the flesh exudes a white latex. When it
first emerges from the ground it looks like a collection of
thick, irregular knobby fingers. The "fingers" expand into
overlapping shelves.
  
More information at MushroomExpert.com:  

Figure 1. Large specimens of Bondarzewia berkeleyi
growing at the base of a diseased red oak tree in New
Hampshire. Specimens this large are hard to miss even
when passing by in a car. Photo © Gary Emberger.

Figure 2. The same tree as in Figure 1. Berkeley's polypore
is present on both sides of the tree. Photo © Gary Emberger.

Figure 3. The large fruitbody in the foreground of Figure 1.
The overlapping (imbricate) caps of this species may
form very large rosettes. Photo © Gary Emberger.

Figure 4. Another large specimen (observed by car) of
Bondarzewia berkeleyi growing at the base of a living
chestnut oak (Quercus montana) in Pennsylvania.
Photo © Gary Emberger.

Figure 5. This specimen (pictured in Figure 4) measured
60 cm at its widest diameter. Photo © Gary Emberger.

Figure 6. Although it may weigh more than 50 pounds at
maturity, Berkeley's polypore starts out small. Gary
Lincoff describes its first appearance as that of a "huge hand
with chunky fingers reaching out of the ground."
Photo © Leon Shernoff.

Figure 7. These specimens of Polyporus berkeleyi
were placed to greet attendees at the 2008 NEMF
foray on the campus of Connecticut College in New
London, CT. Photo © Gary Emberger.

Figure 8. Doris Fleischer found this large specimen of
Bondarzewia berkeleyi during NEMF foray in 2005.
Photo© Doris Fleischer.

Figure 9. No, Linda Brindle's Prius is not powered by
Berkeley's polypore. She wanted to know what this
huge fungus was and transported it to Messiah College
to see me for an identification. Photo © Gary Emberger.

Figure 10. Note the zonate upper surfaces of these caps.
This is the specimen featured in Figure 8. Photo © Gary
Emberger.

Figure 11. The underside of the specimen in Figure 10.
Note that Bondarzewia berkeleyi forms a rooting stalk
5-10 cm long and 3-5 cm thick. Photo © Gary Emberger.


Figure 12. The developing pore surface of a young specimen.
Note the thick, wavy margins. Photo © Pam Kaminski.

Figure 13. Note the irregular appearance of the pores
particularly near the base of the cap. Photo © Gary
Emberger.

Figure 14. The pores of Bondarzewia berkeleyi are
sometimes quite maze-like. Photo © Gary Emberger.