Scientific name: Irpiciporus pachyodon (Pers.) Kotl. &
Pouzar
Derivation of name: Pachyodon means "with thick teeth."
Synonyms: Spongipellis pachyodon (Per.) Kotl. &
Pouzar; Hydnum pachyodon Pers.; Irpex mollis Berk
& M.A. Curtis; Sarcodontia pachyodon (Pers.) Spirin
Common name(s): Spongy toothed polypore, marshmallow
polypore.
Phylum: Basidiomycota
Order: Polyporales
Family: Polyporaceae
Occurrence on wood substrate: Parasitic and saprobic;
effused-reflexed, spreading, single or overlapping caps on
fallen logs and living hardwoods, particularly oak; from July
through October, overwinters.
Dimensions: Individual caps 2.5 to 5 cm wide and long with
individual caps and effused portions fusing to form larger
sheets 20 cm or more wide. Context up to 1 cm thick.
Description: Stalkless caps are white to ochraceous; finely
tomentose to glabrous; white to ochre tubes initially poroid
but eroding to form flattened and cylindrical teeth 0.5 to 1.5
cm in lengh; teeth often decurrent onto effused portions.
Edibility: Inedible.
Comments: As reflected in the order name, Polyporales,
Irpiciporus pachyodon is actually a poroid fungus. Several
other poroid fungi (see Poroid Group A key) have pores
which break down to form teeth. This parasite causes a
white heart-rot of living
broadleafed trees, particularly oak.
More Information at MushroomExpert.com
![](../images/Spongipellis%20pachyodon%20habit%20MR.jpg)
Figure 1. Irpiciporus pachyodon in the field.
Photo © Mike Romankiewicz.
![](../images/Spongipellis%20pachyodon%20closer%20MR.jpg)
Figure 2.
Individual caps and effused portions of
Irpiciporus pachyodon may fuse together to form large
sheetlike fruit bodies. Photo © Mike Romankiewicz.
![](../images/Spongipellis-pachyodon-habitGE.jpg)
Figure
3. Spongy toothed polypore parasitizing a white oak
tree (Quercus alba) in
New Hampshire.
Photo © Gary Emberger.
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![](../images/Spongipellis-pachyodon-habitcloseupGE.jpg)
Figure 4.
The many teeth of Irpiciporus pachyodon resemble
stalactites found in caves.
Photo © Gary Emberger.
Figure 5. Azonate caps of
Irpiciporus pachyodon.
Photo © Gary Emberger.
![](../images/Spongipellis-pachyodon-context2GE.jpg)
Figure 6. The white flesh of the cap is evident in this
sectioned specimen. Photo © Gary Emberger.
![](../images/Spongipellis%20pachyodon%20habit%20GE.jpg)
Figure 7. Effused-reflexed fruit body of Irpiciporus
pachyodon. The teeth are decurrent onto the effused
portion of the fruit body. Photo is of a dried herbarium
specimen.
Photo © Gary Emberger.
![](../images/Spongipellis%20pachyodon%20teeth%20GE.jpg)
Figure 8. The
teeth of Irpiciporus pachyodon are
flattened and may be quite long, up
to 1.5 cm
in length.
Photo is of the specimen in Figure 7, sectioned.
Photo © Gary Emberger.
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