|Major Groups > Polypores > Phaeolus schweinitzii|
by Michael Kuo
This mushroom is a classic "butt rot" fungus, attacking trees through their roots and producing decay in the root system and the heartwood of the lower portion of the tree (up to about 10 or 20 feet above ground). The result is a weakened, or even hollow, tree base--which makes the tree more susceptible to windthrow, especially if other agents (beetles, for example) have combined destructive forces with the fungus.
Phaeolus schweinitzii is partial to conifers, and is usually found near the base of the tree's trunk, appearing terrestrial. It has a velvety, brown to olive cap and, when young, a strikingly yellow or orange, brown-bruising pore surface and margin. The pores are angular and fairly large, and the fairly thin, flexible flesh is brown to reddish brown. With age the mushroom's colors are more boring and brown, but the pore surface usually retains a greenish hue. Microscopic features (see below) are distinctive.
Old specimens of Phaeolus schweinitzii can cause confusion, since they are often no longer velvety and lack any hints of the interesting yellow and orange shades they displayed in their youth. Even the pore surface turns entirely brown, and no longer bruises.
Ecology: Parasitic on the roots and heartwood of living conifers and saprobic on dead wood; causing a brown to reddish brown cubical rot; annual; "especially common in old-growth timber with basal fire scars" (Gilbertson & Ryvarden, 1987); common on Douglas-fir in the West, white pine in eastern North America, and loblolly pine in the South; widely distributed throughout North America where conifers are present.
Cap: Usually with loosely arranged, large lobes arising from a single stem-like structure that emerges from the ground, but occasionally in fused, shelving brackets attached to the base of the tree; up to 35 cm across; velvety to hairy when young, becoming bald in old age; roughening and developing more or less concentric grooves; bright yellow or orange at first, becoming brown to olive brown from the center to the margin with age; with concentric zones of color and texture; often when found more or less brown with a yellow to olive margin.
Pore Surface: Orange to bright yellow when young, becoming greenish yellow, then brownish, and eventually reddish brown; bruising promptly dark brown to black; with 1-2 angular or almost slot-like pores per mm; tubes to 1.5 cm deep.
Stem: Usually present as a more or less central structure up to about 6 cm long and 4 cm thick; brown and velvety below the pore surface, which extends onto the stem surface.
Flesh: Yellowish brown becoming rusty brown; fairly soft when young, becoming stringy and leathery; often appearing zoned.
Odor: Sweetly fragrant, or not distinctive.
Chemical Reactions: KOH black on flesh and cap surface, often with a cherry red intermediate stage (especially with younger specimens).
Spore Print: Whitish to yellowish.
Microscopic Features: Spores 6-9 x 2.5-5 µ; smooth; broadly elliptical; inamyloid; hyaline in KOH. Setae absent. Cystidia occasional to abundant; cylindric-flexuous, with subclavate to clavate or somewhat irregular apices; brown in KOH; 20-90 x 7-13 µ. Hyphal system monomitic; contextual hyphae thin-walled, simple-septate, branching, brown in KOH, 3-17 µ wide.
REFERENCES: (Fries, 1821) Patouillard, 1900. (Saccardo, 1888; Overholts, 1953; Smith, Smith & Weber, 1981; Arora, 1986; Gilbertson & Ryvarden, 1987; States, 1990; Phillips, 1991/2005; Lincoff, 1992; Metzler & Metzler, 1992; Evenson, 1997; Barron, 1999; Roody, 2003; McNeil, 2006; Miller & Miller, 2006; Trudell & Ammirati, 2009.) Herb. Kuo 01120611, 01140603, 01150603, 08250602, 09060803.
Further Online Information:
Cite this page as:
Kuo, M. (2010, February). Phaeolus schweinitzii. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/phaeolus_schweinitzii.html