Russula ochroleucoides

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

by Michael Kuo

This beautiful yellow Russula was originally described by Kauffman, in 1918, on the basis of collections made under oaks and maples in Michigan. The range of the species has since been expanded to include oak and beech forests throughout most of eastern North America. Russula ochroleucoides has a white (or very faintly yellowish) stem, which helps to separate it from Russula flavida, which is also yellow and also appears in oak forests, but features a very yellow stem. The yellow Russula claroflava grows in northern conifer bogs and birch bogs, and features flesh and surfaces that bruise slowly gray.

Description:

Ecology: Mycorrhizal with oaks and with beech; growing alone, scattered, or gregariously; June to October; widely distributed in eastern North America.

Cap: 4-12 cm; convex, becoming broadly convex to flat, or with a shallow depression; dry (one of the illustrated collections was made immediately after a rain, causing the mushrooms to appear slimy); finely velvety, more or less smooth, or developing a network of cracks and fissures; medium yellow to pale yellow; the margin at most vaguely lined; the skin not peeling away easily.

Gills: Attached to the stem; close; whitish, sometimes developing brownish spots and discolorations.

Stem: 3.5-8 cm long; 1-3.5 cm thick; more or less equal; hollowing somewhat with maturity; sometimes finely dusted or hairy; white, but sometimes pale yellowish near the base; occasionally discoloring brownish in places.

Flesh: White; unchanging on exposure.

Odor and Taste: Odor not distinctive, or faintly fragrant; taste mild or, more commonly, slowly somewhat bitter or acrid.

Chemical Reactions: KOH on cap surface negative. Iron salts negative or slowly pink on stem surface.

Spore Print: White or creamy.

Microscopic Features: Spores 7-9 x 5.5-8 µ; broadly elliptical; with warts that usually project less than 1 µ but occasionally reach 1.2 µ; connectors usually forming partially reticulate areas. Pileipellis a cutis underneath a turf-like layer of erect elements, hyaline in KOH, with rounded to subacute apices; some elements with thick walls; pileocystidia up to about 140 x 8 µ, clavate to cylindric, positive in sulphovanillin and with refractive-ochraceous contents in KOH.

REFERENCES: Kauffman, 1918. (Kauffman, 1918; Bills, 1984; Kibby & Fatto, 1990; Phillips, 1991/2005; Roody, 2003; McNeil, 2006.) Herb. Kuo 07140404, 07250402, 07180709, 07010803, 07210801.

"Russula ochraleucoides" (with an "a") is a misspelling originally made by Kauffman; later mycologists corrected his Latin.

Further Online Information:

Russula ochroleucoides at Roger's Mushrooms
Russula ochroleucoides at Russulales News

Iron salts

Spores

Pileocystidia

Thick-walled pileipellis elements

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