Polyporus radicatus

[ Basidiomycetes > Polyporales > Polyporaceae > Polyporus . . . ]

by Michael Kuo

This Midwestern and eastern polypore appears to be terrestrial, but it probably actually fruits from buried wood. It is nearly always solitary, and on casual inspection it looks like anything but a polypore--until you feel its tough consistency and see the underside of the cap, which has a white, Polyporus-ish pore surface.

The distinguishing feature of the species is likely to be snapped off by accident when you pick it: it has a long, rooting stem that extends underground. Above ground, the stem is a dirty yellowish color, but the underground section is black.

Just handle Polyporus radicatus and you will cease wondering about its edibility; its flesh is very tough and corky.

Description:

Ecology: Saprobic on the roots of dead hardwoods (or the dead roots of living hardwoods); causing a white rot; growing alone or scattered; summer through fall; most common in the Mississippi and Ohio valleys, but also reported from eastern North America.

Cap: 3.5-25 cm (but see comments below); broadly convex to flat or shallowly sunken; round in outline; dry; velvety or roughened; yellowish brown to reddish brown.

Pore Surface: White or in age dingy yellowish; running down the stem; 2-3 angular pores per mm; tubes 1-5 mm long.

Stem: Central; 6-15 cm long; .5-2.5 cm wide; more or less equal, or enlarged towards base; dry; dirty yellowish above ground; with a 6-13 cm black "root" extending underground.

Flesh: White; tough.

Spore Print: White.

Microscopic Features: Spores 12-15 x 6-8 µ; smooth; elliptical. Cystidia absent. Clamp connections occasional.

REFERENCES: Schweinitz, 1832. (Overholts, 1953; Smith, Smith & Weber, 1981; Gilbertson & Ryvarden, 1987; Phillips, 1991/2005; Lincoff, 1992; Barron, 1999; Roody, 2003.) Herb. Kuo 07139401, 08230205, 06110303, 08040303.

I have doubts about the possibility of 25-centimeter caps. My dinner plates are this width! I have probably seen Polyporus radicatus 50 times, and I have never seen a cap bigger than about 10 cm. Smith (1981), Phillips (1991), and Lincoff (1992) all cite "3.5-25 cm" as the width of the cap; I suspect that all of these authors are simply quoting Overholts (1953), who either examined some monstrous Polyporus radicatus specimens, or misstated the dimensions.

Further Online Information:

Polyporus radicatus at Roger's Mushrooms

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Cite this page as:

Kuo, M. (2004, November). Polyporus radicatus. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/polyporus_radicatus.html