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."


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.

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).

Further Online Information:

Ischnoderma resinosum at Roger's 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: