Leucopaxillus albissimus

[ Basidiomycetes > Agaricales > Tricholomataceae > Leucopaxillus . . . ]

by Michael Kuo

Leucopaxillus albissimus is a medium-sized to large decomposer of conifer debris with highly variable cap colors--ranging from the "whitest" white referred to by the species name "albissimus," to buff, pinkish, pale brownish, or pale tan. Its whitish to pale yellowish gills, like the gills in most species of Leucopaxillus, can be separated from the cap as a layer (slide the tip of your thumb near the apex of the stem), and copious white mycelium extends from the stem base. Under the microscope, the amyloid, spiny spores are usually longer than 5.5 µ.

Many varieties and forms of Leucopaxillus albissimus have been described on the basis of tastes, colors, and geography. At least one of these taxa (Leucopaxillus paradoxus) is considered a separate species by some mycologists--and if you are in western North America, compare Leucopaxillus albissimus with "Leucopaxillus albiformis," which has a stocky, roughened-scaly stem that is distinctively swollen, with a tapering bottom portion. Hardwood litter-decomposing versions of Leucopaxillus albissimus have been recorded, but these are rare and, at least in eastern North America, may better correspond to Leucopaxillus laterarius.

Leucopaxillus albissimus is probably not poisonous, but most forms smell terrible and many are bitter or otherwise foul tasting--and beginners could easily confuse it with potentially deadly species of Clitocybe. I do not recommend experimenting.

Description:

Ecology: Saprobic, decomposing the litter of conifers; growing scattered, gregariously, or in arcs or fairy rings; widely distributed in North America; summer and fall (over winter in warmer climates).

Cap: 3-20 cm; convex with an inrolled margin when young, becoming broadly convex, flat, or shallowly depressed; dry; smooth or very finely velvety (like kid leather); white, pinkish, buff, pale brownish, or pale tan; often darker with age and/or darker toward the center; the margin sometimes broadly lined at maturity.

Gills: Attached to the stem or running down it; close; separable from the cap as a layer; whitish to dirty yellowish when mature; sometimes forking.

Stem: 3-8 cm long; up to 3 cm thick; not infrequently slightly off-center; when young often slightly swollen near the base but by maturity usually more or less equal; smooth or very finely hairy but not roughened-scaly; whitish; with prominent and copious basal mycelium.

Flesh: White; thick; hard; not changing on exposure.

Odor and Taste: Odor not distinctive or (more commonly) mealy to foul; taste mild, mealy, unpleasant, or bitter.

Spore Print: White.

Chemical Reactions: Cap surface negative to pale olive with KOH.

Microscopic Features: Spores 5-8 x 4.5-5 µ (including ornamentation); more or less elliptical; spiny with warts up to .4 µ; amyloid. Cheilocystidia scattered; long-cylindric; to about 35 µ. Pleurocystidia absent.

Leucopaxillus cerealis is the proper name for Leucopaxillus albissimus, according to most European treatments, the Index Fungorum, and Singer (1986)--the mycologist who transferred Peck's species to Leucopaxillus in the first place. I am only retaining "albissimus" to avoid confusion, since the name is used throughout North American treatments.

REFERENCES: (Peck, 1873) Singer, 1939. (Kauffman, 1918; Singer & Smith, 1943; Smith, Smith & Weber, 1979; Arora, 1986; States, 1990; Phillips, 1991/2005; Lincoff, 1992; Evenson, 1997; Miller & Miller, 2006.) Herb. Kuo 09200602, 09200603, 08160701.

Further Online Information:

Leucopaxillus albissimus at Roger's Mushrooms

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Cite this page as:

Kuo, M. (2007, February). Leucopaxillus albissimus. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/leucopaxillus_albissimus.html