Public Description of Ischnoderma resinosum (Schrad.) P. Karst.

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Name: Ischnoderma resinosum (Schrad.) P. Karst.
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 Draft For 2008/2009 Eol University Species Pages Initiative By Justin Beams (Private)

Description status: Approved
 (Latest review: 2010-04-11 23:20:12 AEST (+1000) by nathan)

Taxonomic Classification:

Domain: Eukarya
Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Polyporales
Family: Fomitopsidaceae

General Description:

Ischnoderma resinosum (Fr.) Karst. is a polypore common in the North American hardwood forests. It is easily identifiable upon a detailed inspection. When fresh, it is a characteristically soft polypore with a notably velvet like texture on the top portion of its cap. The vast majority of specimens are fan shaped on decaying hardwoods with caps that can range from 3-10”. The velvety top surface has notable zones/rings that radiate outward from the point of attachment. Young specimens are distinctly moist and will seep water when crushed. Distinct from other polypores, Ischnoderma resinosum is very fleshy especially when young. The spore bearing underside is white but quickly turns brown and bruises with slight pressure. As the specimen becomes larger and ages, it quickly becomes tough with a leather like texture similar to other polypores.
Common name: Resinous Polypore

Diagnostic Description:

Identification of this species is easy with close examination. The fungus grows a shelf like cap similar to many other polypores. The top surface is brown to dark brown with traces of dark orange. The underside is a very clean white bruising easily to dark tan/brown when contacted with mild pressure. Ischnoderma resinosum spores leave an off whitish print. The spores are hyaline and cylindric/sausage like with sizes ranging from 4.5-7 × 1.5-2.5μm. The cap will slowly turn a dark gray/black with application of 3% KOH.


Ischnoderma resinosum is found in moderate hardwood forests throughout North America. It grows primarily on fallen hardwoods. It is generally not found on heavily decayed logs.


Ischnoderma resinosum is restricted to growing on dead hardwoods. Generally this species favors 1-2 year old logs as opposed to freshly fallen trees.

Look Alikes:

Ischnoderma resinosum is commonly mistaken in Europe with Ischnoderma benzoinus, which is found to grow on conifers. The two are separated by many mycologists with Ischnoderma resinosum’s significantly darker flesh on the top of the fruiting body.


Ischnoderma resinosum currently has no practical industrial use. However it is an important part in the decay of many dead hardwoods, especially ~2 years after their death. It is considered to be inedible by many. However, the younger specimens can be consumed and are enjoyed by some people. For human consumption the younger fungi are chosen simply due to their softer texture.


Bessette, A., Bessette, A., & Fischer, D. (1997). Mushrooms of northeastern north america. Hong Kong: PrintNet.

Kuo, M. (2004, October). Ischnoderma resinosum. Retrieved from the MushroomExpert.Com Web site:


Common name: Resinous Polypore

Description authors: Tom Volk, Justin Beams (Request Authorship Credit)
Description editor: Nathan Wilson