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Paxillus vernalis

[ Basidiomycetes > Boletales > Paxillaceae > Paxillus . . . ]

by Michael Kuo

Paxillus vernalis can fruit in stunning numbers under quaking aspen and paper birch in late summer and fall across northern and montane North America. On casual observation, one is likely to mistake it for a Lactarius--but it does not produce milk when sliced. In fact, close examination reveals several things that are not at all Lactarius-like: the gills separate from the cap in a layer (almost like the separable tube layers in boletes), and they are oddly pore-like and convoluted where they meet the stem. Finally, the spore print is brown, rather than pale.

The better known and more widely distributed Paxillus involutus is practically identical; it features a skinnier stem (usually under 2 cm wide) and grows under a wide variety of trees.

Description:

Ecology: Mycorrhizal with quaking aspen or paper birch; apparently also capable of existing as a saprobe on wood and woody debris; growing scattered or gregariously; late summer and fall; fairly widely distributed in boreal and montane North America.

Cap: 6-20 cm; convex to broadly convex with a strongly inrolled, cottony margin, becoming flat; the margin remaining inrolled; sticky or dry; smooth, somewhat roughened, or finely hairy; brownish yellow, becoming pale rusty brown.

Gills: Running down the stem; crowded; often becoming convoluted or pore-like at the stem; yellowish to pale cinnamon or pale olive; bruising brown to reddish brown.

Stem: 3-9 cm long; 2.5-5 cm thick; thick and sturdy; dry; smooth or finely hairy; colored like the cap or paler; bruising brownish to reddish brown.

Flesh: Thick and firm; yellowish; discoloring reddish to brownish when exposed.

Odor and Taste: Taste acidic; odor not distinctive or somewhat fragrant.

Spore Print: Brown to dark brown.

Microscopic Features: Spores 7.5-10 x 5-6 µ; smooth; elliptical. Pleuro- and cheilocystidia fusoid to fusoid-ventriose; 40-70 µ long; with brownish contents. Clamp connections present.

REFERENCES: Watling, 1969. (Smith, Smith & Weber, 1979; Evenson, 1997; Jarosch & Bresinski, 1999; McNeil, 2006; Miller & Miller, 2006.) Herb. Kuo 08150304.

 

Paxillus vernalis

Paxillus vernalis

Paxillus vernalis

Paxillus vernalis



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Kuo, M. (2007, March). Paxillus vernalis. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/paxillus_vernalis.html