Inonotus obliquus

Scientific name:  Inonotus obliquus (Ach. ex Pers.) Pilat.
Derivation of nameObliquus means "slanted" or
SynonymsBoletus obliquus Ach. ex Pers., Polyporus
(Ach. ex Pers.) Fr.; Poria obliqua (Ach. ex Pers.)
P. Karst  
Common name(s): Clinker polypore, birch conk, birch
canker polypore, chaga. 
Phylum:   Basidiomycota
Order:   Hymenochaetales
Family:   Hymenochaetaceae
Occurrence on wood substrate:  Parasitic; sterile conks
made of fungus tissue forming almost exclusively on trunks
of living birch (Betula) species; conks found year-round. 
Dimensions:  The sterile, black clinker- or cinder-like knobs
or conks can be quite large, 10-40 cm across and irregular in
Description:  Resembling charred wood or a canker-like
growth, the outer surface of the sterile conk is dark brown to
black, hard, and deeply fissured. Internally, the tissue is corky
and yellow to yellow-brown.
Edibility: Used to make a tea called chaga.
Comments:  In addition to the sterile conk, the species forms
an effused, poroid fruiting body beneath the bark or outer
layers of wood on snags or fallen trunks.. This fertile portion
is apparently difficult to find and will not be described further.
Chaga tea is prepared from the sterile conk and used

More information at


Figure 1. Inonotus obliquus on paper birch (Betula
papyrifera). Photo © Greg Marley.

Figure 2. Inonotus obliquus on yellow birch (Betula
alleghaniensis). Photo © Gary Emberger.

Figure 3. A rather elongate specimen. Photo © John
Plischke III.

Figure 4. Rick Van de Poll refers to conks shaped like
this as "pig snout specials." Photo © Rick Van de Poll.

Figure 5. The dark, cracked outer surface of the sterile conk.
Photo © Gary Emberger.

Figure 6. Internally, the clinker polypore is yellowish to
yellow-brown. Photo© Gary Emberger.

Figure 7. Section throrugh Inonotus obliquus showing
attachment to the wood. Detaching the clinker polypore
often requires a hatchet or hammer.
Photo © John Plischke III.

Figure 8. Tea preparation involves breaking chaga into small
pieces. Photo © John Plischke III.

Figure 9. A coffee grinder can be used to prepare a fine
powder used to make chaga tea. Photo © John Plischke III.


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This page © 2008 by Gary Emberger, Messiah College