Fomitopsis spraguei

Scientific name:  Fomitopsis spraguei (Berk. & M.A.
Curtis) Gilb. & Ryvarden
Derivation of nameSpraguei indicates this fungus species
was named after C. J. Sprague. 
SynonymsPolyporus spraguei Berk. & M.A. Curtis;
Tyromyces spraguei (Berk. & M.A. Curtis) Murrill  
Common name(s): None. 
Phylum:   Basidiomycota
Order:   Polyporales
Family:   Fomitopsidaceae
Occurrence on wood substrate: Saprobic and parasitic;
sessile to effused-reflexed on dead wood and at the bases of
living hardwoods, particularly oak; year-round.  
Dimensions: Caps up to 15 cm wide.   
Upper surface:  Caps white to ochraceous to gray; margin
may be somewhat reddish on fresh, growing specimens;
margins of young specimens develop a green color upon
handling; azonate; smooth or slightly grooved, glabrous to
Pore surface: White to cream-colored to pale brown; pores
3-6 per mm.
Edibility: Inedible. 
Comments: Young specimens exude watery drops from the
margin and upper surface. The green discoloration of the
margins is a useful marker for this species, helping to
distinguish it from similar species otherwise differentiated
only by microscopic characters.  

Figure 1. The grayish cap of this young Fomitopsis
specimen is exuding drops of water. Photo
© Cathy Cholmeley-Jones.

Figure 2. Water drops exuding from the pore surfaces as
well as the upper surfaces of these young specimens. Note
the pale reddish coloration at the margin. Photo © Rick
Van de Poll.

Figure 3. The cap of Fomitopsis spraguei is sometimes
described as having the appearance of stone or marble.
Photo © Gary Emberger.

Figure 4. Top surface of a specimen collected during a
NEMF foray. Photo © Gary Emberger.

Figure 5. Bottom surface of specimen in Figure 4.
Photo © Gary Emberger.

Figure 6. Pores (3-6 per mm) visible on the white pore
surface of Fomitopsis spraguei. Photo © Gary

Figure 7. This sectioned cap reveals that the thick context
(flesh) above the pore layer has the same marble-like
appearence as the cap. Photo © Gary Emberger.

Figure 8. The margins on these fresh specimens have
discolored green where they were handled.
Photo © Gary Emberger.

Figure 9. Young speciemen collected at a NEMF foray.
Note the green discoloration where handled.
Photo © Gary Emberger.


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