Major Groups > Polypores > Cryptoporus volvatus


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Cryptoporus volvatus

by Michael Kuo, 24 August 2023

This odd little fungus is pretty much impossible to confuse with anything else. It is a polypore, but you will only know it after inspecting it closely, since the pore surface is cryptically covered by a flap of tissue and the fungus looks rather like a wood-inhabiting puffball. Look for Cryptoporus volvatus on the deadwood of conifers—especially those killed by fire, beetle kill, or disease, in the year after the death of the tree.

Between the pore surface and the covering tissue, spores fall into a chamber and are trapped. If its spore dispersal strategy involved only the "normal" dependence on air currents, Cryptoporus volvatus might have been selected for extinction many moons ago, since the spores cannot fall free of the covering. But Cryptoporus thinks outside the box, and has ingeniously devised an alternative way to disperse spores.

As the fungus matures and spores are released, a tiny trap-door appears on the covering tissue. Wood-boring beetles, in search of food, enter the chamber to feast on the mushroom's tubes and spores—then carry the spores away. When the beetles bore into new wood, Cryptoporus spores are carried along, ready to germinate and take up residence. Additionally, at least one bird (the white-headed woodpecker, Picoides albolarvatus) may help disperse spores by consistently foraging for beetles in Cryptoporus volvatus (Watson & Shaw 2018).


Ecology: Saprobic on the deadwood of conifers, especially pines; growing alone or gregariously, often on trees that were killed by fire, insects, or other causes in the previous year; causing a soft, grayish brown rot in the outer few centimeters of the sapwood; apparently among the first wood-rotting fungi in the line of succession, and rarely found more than a year or two after the tree has died; summer and fall (or over winter in warm climates); originally described from New York (Peck 1875); widely distributed in North America; also reported from South America and eastern Asia. The described and illustrated collection is from California.

Cap: 1.5–5 cm across; 1–3 cm deep; 1–2.5 cm thick; more or less spherical at first, becoming convex and semicircular; sometimes covered with a glossy layer of sap from the host tree; bald; cream colored to yellowish or pale tan.

Pore Surface: Covered by a 1–2.5 mm thick, whitish volva which results from the extension of tissue from the cap margin; pale to dark brown; with 3–5 circular pores per mm; tubes 3–5 mm deep.

Stem: Absent.

Flesh: Whitish, becoming pale brownish with age or when dry; somewhat corky.

Odor: Not distinctive.

Chemical Reactions: KOH dark brown on dried flesh.

Microscopic Features: Spores 11–14 x 4–5.5 µm; elongated-ellipsoid; smooth; hyaline to dull golden in KOH; inamyloid. Basidia 25–30 x 4–8 µm; clavate; 4-sterigmate. Cystidia ("cystidioles") 25–30 x 3–5 µm; lageniform to fusiform; smooth; thin-walled; hyaline in KOH. Hyphal system trimitic. Generative hyphae mostly 3–4 µm wide but occasionally swollen to 11 µm; smooth; thin-walled; hyaline in KOH; clamped at septa.

REFERENCES: (C. H. Peck, 1875) C. L. Shear, 1902. (Murrill, 1903; Zeller, 1915; Overholts, 1953; Harrington, 1980; Smith, Smith & Weber, 1981; Arora, 1986; Gilbertson & Ryvarden, 1986; Lincoff, 1992; Barron, 1999; Kruger, 2002; Roody, 2003; Miller & Miller, 2006; Kuo & Methven, 2010; Justo & Hibbett, 2011; Desjardin, Wood & Stevens, 2015; Evenson, 2015; Cripps, Evenson & Kuo 2016; Siegel & Schwarz, 2016; Binder et al., 2017; Ginns, 2017; Sturgeon, 2018; Watson & Shaw, 2018; Mackinnon & Luter, 2021.) Herb. Kuo 01170511.

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Cryptoporus volvatus

Cryptoporus volvatus

Cryptoporus volvatus

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Kuo, M. (2023, August). Cryptoporus volvatus. Retrieved from the MushroomExpert.Com Web site: