Major Groups > Polypores > Ischnoderma resinosum


Ischnoderma resinosum

[ Basidiomycetes > Polyporales > Hapalopilaceae > Ischnoderma . . . ]

by Michael Kuo

This attractive and widely distributed polypore is easy to recognize--with close inspection. The young mushrooms are thick, soft, and fleshy--much softer than you might expect in a polypore, especially if, from a distance, you thought you were looking at Ganoderma applanatum. The young pore surface is whitish, but it turns brown very quickly when bruised. Ischnoderma resinosum has a tendency to grow not only on the sides of dead logs, but also on their undersides, where it produces a capless version (or extension) of itself that consists primarily of a pore surface (see the illustrations). As Ischnoderma resinosum matures, it becomes very tough and leathery, and much more "polyporeish."

Polyporus resinosus is a former name.

"Ischnoderma benzoinus" is recognized as a separate, conifers-only species by some authors (especially in Europe), who separate it from a hardwoods-only Ischnoderma resinosum on the basis of its putatively darker flesh. Culture studies refute this separation, however, and the reigning authoritative source on North American polypores (Gilbertson & Ryvarden, 1986) synonymizes the two species--as did the previous North American polypore "Bible" (Overholts, 1953).


Ecology: Saprobic on the deadwood of hardwoods and conifers; annual; causing a whitish to yellowish rot that separates the annual rings in the wood and often smells of anise; appearing on recently fallen wood and on wood that has been down for many years, but not typically on well rotted wood; growing alone, gregariously, or in overlapping clusters; usually appearing in fall; very widely distributed in North America.

Cap: Usually present and well developed, but sometimes present merely as a folded-over edge above a spreading pore surface, and occasionally almost entirely absent; up to 20 cm across and 12 cm deep; irregularly bracket-shaped or kidney-shaped; broadly convex; when young quite thick and fleshy, with a pale brownish, finely velvety surface and a thick white margin that can be adorned with water droplets in wet weather; in maturity dark brown, sometimes with zones of color, fairly smooth, dry, and tough.

Pore Surface: When young whitish, soft, promptly bruising brown; in maturity pale brown and hard; with 4-6 angular or round pores per mm; tubes to 1 cm deep.

Stem: Absent.

Flesh: Whitish and soft at first; darkening to brownish or cinnamon brown, and becoming tougher with maturity.

Odor and Taste: Not distinctive.

Chemical Reactions: All parts grayish to blackish with KOH.

Spore Print: White.

Microscopic Features: Spores 5-7 x 1.5-2 µ; smooth; cylindrical; inamyloid. Cystidia absent. Hyphal system dimitic, with clamp connections.

REFERENCES: (Schrader, 1794) Karsten, 1879. (Fries, 1821; Saccardo, 1888; Overholts, 1953; Smith, Smith & Weber, 1981; Gilbertson & Ryvarden, 1986; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Horn, Kay & Abel, 1993; Barron, 1999; Roody, 2003; McNeil, 2006; Kuo, 2007; Binion et al., 2008; Trudell & Ammirati, 2009.) Herb. Kuo 09220407, 10070401.

This website contains no information about the edibility or toxicity of mushrooms.


Ischnoderma resinosum

Ischnoderma resinosum

Ischnoderma resinosum

Ischnoderma resinosum

Ischnoderma resinosum

Ischnoderma resinosum

Ischnoderma resinosum

Ischnoderma resinosum

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Cite this page as:

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