Major Groups > Polypores > Ischnoderma benzoinum


Ischnoderma benzoinum

[ Basidiomycota > Polyporales > Fomitopsidaceae > Ischnoderma . . . ]

by Michael Kuo

This is the conifer-associated version of Ischnoderma resinosum, and it is very similar. Like its hardwood-associated relative, Ischnoderma benzoinum is an annual polypore with a brown-bruising pore surface and a cap that features zones of brown shades. However, Ischnoderma benzoinum is usually a bit thinner than Ischnoderma resinosum, and its flesh is a bit darker. According to Pouzar (1990) the definitive morphological difference between the two species is the color of the tubes when the fruiting bodies are mature; in Ischoderma benzoinum the mature tubes are brown, while mature tubes in Ischnoderma resinosum are creamy to slightly brownish.

North American mycologists generally treat the two species as synonyms. I am not aware (as of this writing) of any contemporary study that has attempted to answer the question with molecular evidence.


Ecology: Saprobic on the deadwood of conifers; annual; causing a white rot; growing alone, gregariously, or in overlapping clusters; usually appearing in fall; North American distribution uncertain because it is usually treated as Ischnoderma resinosum. The illustrated and described collections are from Ohio and Pennsylvania.

Cap: 4–15 cm across; 4–6 cm deep; fan-shaped; broadly convex; dry; finely velvety; with zones of brown and dark brown, and a paler margin—or uniformly brown overall, especially when mature.

Pore Surface: Creamy; bruising brown; in maturity dark brown and hard; with 3–4 round pores per mm; tubes 2–4 mm deep.

Stem: Absent.

Flesh: Pale tan; stringy.

Odor and Taste: Not distinctive.

Chemical Reactions: KOH black on cap surface and flesh.

Spore Print: White.

Microscopic Features: Spores 5–7 x 1–2 µm; allantoid; smooth; hyaline in KOH; inamyloid. Cystidia not found. Hyphal system dimitic; generative hyphae of tube trama 2–5 µm wide, smooth, thin-walled, hyaline to ochraceous in KOH, with clamp connections at septa; skeletal hyphae 4–7 µm wide, with walls 1 µm thick.

REFERENCES: (Wahlenberg, 1826) Karsten, 1879. (Phillips, 1981; Breitenbach & Kränzlin, 1986; Pouzar, 1990; Buczacki et al., 2012; Vesterholt, 2018; Læssøe & Petersen, 2019.) Herb. Kuo 09191501.

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Ischnoderma benzoinum

Ischnoderma benzoinum

Ischnoderma benzoinum

Ischnoderma benzoinum

Ischnoderma benzoinum

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Kuo, M. (2019, December). Ischnoderma benzoinum. Retrieved from the MushroomExpert.Com Web site: