Meripilus sumstinei

Scientific name:   Meripilus sumstinei (Murrill) M. J.
Larsen and Lombard
Derivation of name:   Meri- means "part" or "division"
and pil- means "cap." The genus name may refer to the
structure of the fungus having numerous caps fanning out
and dividing from a common base. sumstinei honors David
Ross Sumstine (1870-1965), a Pennsylvania public
school administrator, Lutheran minister, and amateur
mycologist.
Synonymy:  Meripilus giganteus (Pers.) P. Karst.,
Polyporus giganteus Fr.
Common names:   Black-staining polypore.
Phylum:   Basidiomycota
Order:   Polyporales
Family:  Meripilaceae
Occurrence on wood substrate:  Parasitic and saprobic; on
ground (from roots) around stumps or living deciduous trees,
especially oak; July through November.  
Dimensions:  Individual caps (fronds) 5-20 cm wide, forming
large dense clusters attached to a short, thick common stalk;
stalks (when present) 1-3 cm long and up to 11 cm thick.   
Upper surface: Grayish to yellowish-tan, becoming smoky
and dark with age; radially wrinkled; finely hairy; bruising
black along the margins where handled or in age. 
Pore surface: White; bruising black; pores 4-7 per mm.
Comments: Clusters of Meripilus sumstinei may attain
diameters of 40 cm or more.

More information at MushroomExpert.com:   
    

Figure 1. Terestrial rosette of Meripilus sumstinei at the
base of a tree trunk. Photo © Tom Schulein.

Figure 2. The many dead roots associated with this large
oak tree stump may continue supporting the growth of
numbers of specimens of Meripilus sumstinei for many
years. Photo © Gary Emberger.

Figure 3. Black-staining polypore may be saprophytic,
living on dead wood (this view) or parasitic (see Figure
5). Photo © Gary Emberger.

Figure 4. The white pore surface visible under one frond
contrasts nicely with the darker colors of the upper cap
surface. Photo © Cathy Cholmeley-Jones.

Figure 5. The rosettes in the foreground, parasitizing
the roots, are some distance from the trunk of the
host tree. Photo © Gary Emberger.

Figure 6. Note the blackish bruising on some of the fronds
(caps) of this specimen. Photo © Gary Emberger.

Figure 7. A specimen collected at a NEMF foray. Older
specimens become darker with age. Photo © Gary
Emberger.

Figure 8. The cap surfaces turn black where touched.
Photo © Gary Emberger.


Figure 9. The pores of Black-staining polypore are very
small, giving the pore surface a uniformly white, almost
"pore-less" appearance. Where touched, the pores stain
black. Photo © Gary Emberger.