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Russula cremoricolor

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

by Michael Kuo

Russula cremoricolor is a winter regular in the mixed forests of coastal California. It features a white spore print, acrid taste, and a cap that is either creamy yellowish to whitish or bright red--a relatively recent idea supported by DNA evidence (Redecker and collaborators, 2001), though collectors in the area have long noted the extensive similarities between the cream and red forms (e.g. Arora, 1986). The red form has previously been labeled "Russula emetica" and "Russula silvicola"; see the comments below for more information.

Microscopic features for Russula cremoricolor include spores with fairly isolated warts, and abundant pileocystidia.


Ecology: Mycorrhizal; found in mixed forests; typically growing gregariously but sometimes growing alone or scattered; late fall through spring; California and the Pacific Northwest.

Cap: 3-10 cm; convex when young, becoming broadly convex to flat, sometimes with a shallow depression; sticky when wet; fairly smooth; bright red or creamy yellowish to nearly white; the margin usually somewhat lined at maturity; the skin peeling fairly easily, about halfway to the center.

Gills: Attached to the stem; close or nearly distant; white, sometimes becoming creamy with maturity.

Stem: 2-10 cm long; 1-2.5 cm thick; white; dry; fairly smooth.

Flesh: White; unchanging when sliced.

Odor and Taste: Odor not distinctive; taste immediately strongly acrid.

Spore Print: White.

Chemical Reactions: Iron salts on stem surface negative to pinkish.

Microscopic Features: Spores 7.5-10.5 x 6-8.5 µ; with mostly isolated warts extending .3-1 µ high; connectors scattered, not usually creating reticulated areas. Pileipellis a cutis embedded in a gelatinous matrix; pileocystidia abundant, cylindric to subclavate or subfusiform, to 150 x 10 µ, ochraceous-refractive in KOH and positive in sulphovanillin.

REFERENCES: Earle, 1902. (Saccardo, 1905; Burlingham, 1915; Arora, 1986; Thiers, 1997b; Redecker et al., 2001; Roberts, 2008.) Herb. Kuo 02200301, 01110603.

For many years the red form of Russula cremoricolor was identified as Russula emetica--a European species that North American authors have traditionally assumed to be present on our continent. Shaffer (1975) described it from North America as a species limited to habitat in sphagnum, possessing multi-septate pileocystidia; he created Russula silvicola for eastern North American collections from different habitats, featuring non-septate or sparsely septate pileocystidia. West Coast collectors subsequently began to apply the name Russula silvicola to the red form of Russula cremoricolor. Thus it would be inaccurate to reduce Russula silvicola to synonymy with Russula cremoricolor (which is the older of the two names), since Shaffer's eastern species name was probably misapplied to West Coast material. Redecker and collaborators (2001) did not compare any of their California collections with eastern collections, nor with the type collection of Russula silvicola, from Cheboygan County, Michigan.

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Russula cremoricolor

Russula cremoricolor

Russula cremoricolor

Russula cremoricolor

Russula cremoricolor

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Kuo, M. (2009, March). Russula cremoricolor. Retrieved from the MushroomExpert.Com Web site: