Major Groups > Polypores > Stemmed, Pale-Fleshed > Bondarzewia berkeleyi


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Bondarzewia berkeleyi

by Michael Kuo, 3 October 2022

Elias Fries, often seen as the father of mycology, declared Bondarzewia berkeleyi the "most noble of all the polypores known to me" (1851, my translation). Fries was studying an unnamed collection from North Carolina he found in the herbarium of English mycologist Miles Joseph Berkeley, and it was apparently quite a big one. I have seen specimens 2 feet across, and over the years I have been sent photos of specimens that appeared even bigger.

"Berkeley's polypore," as it is sometimes called, is found at the bases of (doomed) hardwoods in eastern North America, where it grows as a parasitic butt rot. Young specimens are nearly white, but the fungus becomes cream-colored to pale yellowish as it matures. A number of individual caps form the large rosette that comprises the mushroom, and an eccentric stem-like structure is usually found hiding below the caps. The pore surface is colored like the cap, and does not bruise appreciably.

Bondarzewia berkeleyi provides great support for the idea that "polypores" are examples of convergent evolution rather than naturally related organisms. DNA studies for the past several decades have been unequivocal: Bondarzewia belongs in the family Russulaceae, more closely related to russulas and milky caps than to other polypore genera (a relationship hinted at by the russula-like spores of Bondarzewia berkeleyi). See What, If Anything, Is a Gilled Mushroom? for more discussion of convergent evolution.

In western North America, Bondarzewia occidentalis (formerly known as Bondarzewia montana and Bondarzewia mesenterica) is a similar species fruiting on the wood of conifers; it has a brown cap surface at maturity.


Ecology: Parasitic on hardwoods (especially oaks), causing a white, stringy butt rot; also saprobic on the deadwood of hardwoods; growing alone or gregariously at the bases of trees; summer and fall; originally described from North Carolina; widely distributed in North America east of the Great Plains; occasionally reported from Mexico. The illustrated and described collections are from Illinois, Indiana, and North Carolina.

Fruiting Body: 20–50 or more cm across; consisting of one to several spiraling caps arising from a single, gnarled stem-like structure.

Individual Caps: 6–25 cm across; kidney-shaped or irregular in outline; loosely convex, flat, or with a central depression; dry; velvety or leathery; sometimes radially wrinkled (but never scaly) or with vague, semi-concentric zones of texture or color; white when young, becoming cream colored to dull yellowish and eventually sometimes brownish; not bruising, or occasionally bruising yellowish on the growing margin.

Pore Surface: Running down the stem; whitish; not bruising, or bruising very faintly yellowish to brownish; pores circular when young, 1–2 per mm—becoming angular and wider with age; tubes shallow, often much less than 1 cm deep.

Stem: 4–10 cm long; 3–5 cm wide; usually somewhat off-center and poorly defined; whitish to dull yellowish; dry; tough.

Flesh: White; thick; not discoloring or bruising.

Odor and Taste: Not distinctive.

Chemical Reactions: KOH negative to orangish on cap surface; negative to dirty yellow on flesh.

Spore Print: White.

Microscopic Features: Spores 6–7.5 µm without ornamentation; globose to subglobose; ornamented with densely packed, amyloid, blunt-tipped spines 1–2 µm long. Basidia 40–50 x 7.5–12 µm; clavate; 4-sterigmate. Cystidia not found. Setae not found. Hyphal system dimitic, with thick-walled and aseptate skeletal hyphae, and thin-walled generative hyphae; clamp connections not found.

REFERENCES: (Fries, 1851) Bondartsev & Singer, 1941. (Overholts, 1953; Smith, Smith & Weber, 1981; Arora, 1986; Gilbertson & Ryvarden, 1986; Phillips, 1991/2005; Lincoff, 1992; Barron, 1999; Larsson et al., 2003; Roody, 2003; Miller & Miller, 2006; Binion et al., 2008; Kuo & Methven, 2010; Kuo & Methven, 2014; Das et al., 2015; Chen et al., 2016; Baroni, 2017; Woehrel & Light, 2017; Elliott & Stephenson, 2018; Sturgeon, 2018; McKnight et al., 2021.) Herb. Kuo 08040305, 06220801, 06221014, 08311302, 07281601, 09292201.

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Bondarzewia berkeleyi

Bondarzewia berkeleyi

Bondarzewia berkeleyi

Bondarzewia berkeleyi

Bondarzewia berkeleyi

Bondarzewia berkeleyi

Bondarzewia berkeleyi

Bondarzewia berkeleyi

Bondarzewia berkeleyi

Bondarzewia berkeleyi

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Kuo, M. (2022, October). Bondarzewia berkeleyi. Retrieved from the MushroomExpert.Com Web site: