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Russula crustosa

[ Basidiomycetes > Russulales > Russulaceae > Russula . . . ]

by Michael Kuo

With its quilted cap, Russula crustosa looks like a pale, brownish yellow version of the green-capped Russula virescens. Close inspection, however, usually reveals a few differences beyond the color of the cap: the patchwork areas of Russula crustosa have sharper edges and are more clearly delineated than those of Russula virescens; there are usually more pleurocystidia in Russula crustosa (in Russula virescens they are scarce or absent); and the tips of the terminal cells in the pileipellis are generally more rounded in Russula crustosa.

Description:

Ecology: Mycorrhizal with oaks and perhaps with other hardwoods; growing alone, scattered, or gregariously; summer; widely distributed east of the Rocky Mountains.

Cap: 5-10 cm; round to convex when young, becoming broadly convex to flat or uplifted, with a shallow depression; dry; soon cracking up into clearly defined patches that have fairly abrupt edges; buff, yellowish brown or faintly olive; the margin lined at maturity; the "skin" peeling about halfway to the center.

Gills: Attached to the stem; close or crowded; some forking; white to creamy.

Stem: 3.5-9 cm long; 1.5-3 cm thick; white; dry; smooth.

Flesh: White; brittle; thick.

Odor and Taste: Odor not distinctive; taste mild.

Chemical Reactions: KOH on cap surface negative. Iron salts on stem surface negative or pink (sometimes slowly and/or faintly).

Spore Print: White to creamy.

Microscopic Features: Spores 6-9 x 5.5-7 µ; elliptical to nearly round; warts extending to about 0.5 µ high; connectors scattered and rare, usually not forming reticula. Pleurocystidia scattered to abundant; mucronate with a lengthened or subglobose extension. Pileipellis a cutis beneath an epithelium-like layer (the patches) of erect, chained elements, with the terminal cell featuring a blunt to somewhat elongated projection with a rounded (only rarely subacute) apex; pileocystidia very long, arising in the cutis, positive in sulphovanillin and refractive-ochraceous in KOH.

REFERENCES: Peck, 1902. (Saccardo, 1891; Burlingham, 1915; Beardslee, 1918; Kauffman, 1918; Kibby & Fatto, 1990; Phillips, 1991/2005; Lincoff, 1992; Barron, 1999; McNeil, 2006; Buyck, 2007; Binion et al., 2008.) Herb. Kuo 06249503, 06220401, 07150702, 06240802.

Russula crustosa appears to be frequently confused with Russula virescens and with what is now called Russula parvovirescens; many of the sources cited above feature one or the other of these decidedly green species as "Russula crustosa," which is consistently brownish yellow or faintly olive.

Further Online Information:

Key to Virescentinae in US at Russulales News
Russula crustosa at Roger's Mushrooms
Russula crustosa at Russulales News

 

Russula crustosa

Russula crustosa

Russula crustosa

Russula crustosa

Russula crustosa
Pleurocystidia

Russula crustosa
Terminal cells in pileipellis

Russula crustosa
Pileocystidium


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Cite this page as:

Kuo, M. (2009, March). Russula crustosa. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/russula_crustosa.html