Major Groups > Polypores > Inonotus quercustris


Inonotus quercustris

[ Basidiomycetes > Hymenochaetales > Hymenochaetaceae > Inonotus . . . ]

by Michael Kuo

Originally described as a parasite on urban water oaks in Baton Rouge, Inonotus quercustris has since been documented in Texas and Argentina--and now, apparently, from the Mingo National Wildlife Refuge in southern Missouri. The Mingo swamps are a bit out of place; they represent a Gulf-Coast ecosystem far north of the Gulf Coast, and several otherwise-southern species are found there. In the Mingo refuge Inonotus quercustris attacks living red oaks (including water oak and willow oak), and the large polypores appear high on the trees.

Aside from its ecology, the species is characterized by its large, soft fruiting bodies with velvety, yellow to rusty brown caps; a yellowish-then-brownish pore surface; watery flesh that is streaked and reminiscent of the flesh of Fistulina hepatica; and microscopic features (including ellipsoid spores and impressive setal hyphae).

The Mingo collections agree with previous descriptions of Inonotus quercustris with the exception of spore dimensions, which are somewhat smaller (see below).


Ecology: Parasitic on living oaks (especially water oak); causing a white heart rot; annual; growing alone, gregariously, or in shelving clusters; usually found high on the tree (often out of reach); appearing year-round; to be expected along the Gulf Coast.

Cap: Up to 40 cm across and 20 cm deep; semicircular to fan-shaped; planoconvex or flat; velvety to finely hairy or, in age, nearly bald; yellow to orangish yellow, becoming rusty brown with age; the margin thick and soft when young.

Pore Surface: Bright yellow to creamy when young, becoming yellowish brown; bruising brown when young; with 3-5 angular pores per mm; tubes to 3 cm deep.

Stem: Absent.

Flesh: Reddish brown; soft and watery at first, becoming tougher with age; faintly zoned or streaked (when young specimens are sliced the flesh is reminiscent of the flesh in Fistulina hepatica).

Odor and Taste: Odor not distinctive; taste tangy or sour.

Chemical Reactions: Flesh and cap surface red to maroon, then quickly black with KOH.

Spore Print: Not documented; probably yellowish to brownish.

Microscopic Features: Spores 9-10 x 6-8 µ (Louisiana; Blackwell & Gilbertson), 7-10 x 5-7 µ (Argentina; Gottlieb et al.), or 5.5-7 x 4-5.5 µ (Missouri); smooth; ellipsoid; pale yellowish to brownish in KOH; inamyloid. Hymenial setae absent. Setal hyphae (tramal setae) dark reddish brown; thick-walled; long, with a tapered, fusoid end; to over 200 µ long and 10 µ wide. Hyphal system monomitic. Clamp connections absent.

REFERENCES: Blackwell & Gilbertson, 1985. (Gilbertson & Ryvarden, 1986; Metzler & Metzler, 1992; Gottlieb et al., 2006.) Herb. Kuo 09180403, 09240508.

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Inonotus quercustris

Inonotus quercustris

Inonotus quercustris

Inonotus quercustris

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Kuo, M. (2010, March). Inonotus quercustris. Retrieved from the MushroomExpert.Com Web site: