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 Polyporus 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.

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

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

Figure 4. Another specimen at the base of a tree.
Photo © Larry Grand.

Figure 5. 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.

Figure 6. Doris Fleischer found this large specimen of
Bondarzewia berkeleyi during NEMF foray in 2005.
Photo© Doris Fleischer.

Figure 7. 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

Figure 8. Note the zonate upper surfaces of these caps. This
is the specimen featured in Figure 2.

Figure 9. The underside of the specimen in Figure 5. Note
that Bondarzewia berkeleyi forms a rooting stalk 5-10 cm
long and 3-5 cm thick.


Figure 10. The developing pore surface of a young specimen.
Note the thick, wavy margins. Photo © Pam Kaminski.

Figure 11. Note the irregular appearance of the pores
particularly near the base of the cap.

Figure 12. The pores of Bondarzewia berkeleyi are sometimes
quite maze-like.