Cryptoporus volvatus

[ Basidiomycetes > Polyporales > Polyporaceae > Cryptoporus . . . ]

by Michael Kuo

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-rotting puffball.

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.

Cryptoporus volvatus is too tough to consider for the table--unless you are a wood-boring beetle, in which case you might also want to consider the table for the table.

Description:

Ecology: Saprobic on the dead wood of conifers; growing alone or gregariously, often on trees that were killed by fire, insects, or other causes in the previous year; summer and fall (and winter in coastal California); widely distributed in North America; 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. "On Douglas-fir, C. volvatus is often associated with old bark beetle galleries and can be used as an indicator of bark beetle kill" (Canadian Forest Service, 2003; link below).

Fruitbody: Up to 5 cm across; more or less spherical in appearance; smooth or with a lacquered gloss; yellowish, cream colored, or tan.

Pore Surface: Covered by a "volva" which results from the extension of tissue from the cap margin; pale to dark brown; pores circular, 4-5 per mm; tubes to 6 mm deep.

Flesh: White; somewhat corky.

Spore Print: Pinkish.

Microscopic Features: Spores 12-17 x 4-5 µ; smooth; cylindric.

REFERENCES: (Peck, 1877) Shear, 1902. (Overholts, 1953; Smith, Smith & Weber, 1981; Arora, 1986; Gilbertson & Ryvarden, 1986; Lincoff, 1992; Evenson, 1997; Barron, 1999; Roody, 2003.) Herb. Kuo 01170511.

Further Online Information:

Cryptoporus volvatus at MykoWeb
Grey-Brown Sap Rot at Tree Diseases of BC

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