Russula amoenolens & Russula cerolens

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by Michael Kuo

Identification of precise species in Russula is often speculative, and it can become awfully difficult to draw definitive lines within some groups of mushrooms. The brown, acrid members of the Foetid Russula Group form one such cluster of species. Their waxy benzaldehyde odor, somewhat reminiscent of maraschino cherries, separates them from Russula sororia, and their brown colors separate them from the paler, straw yellow Russula pectinatoides (which is also somewhat more fragile, and usually less acrid). But distinguishing between species within the group is nearly an exercise in futility, in my opinion, with or without a microscope.

Russula amoenolens is the principal "species" in the group; in theory, it has a moderately waxy-acrid taste, light yellowish brown colors, and a stem that bruises or discolors yellowish brown (if at all). Russula cerolens, by "contrast," has darker brown colors, strongly acrid taste, and a stem that discolors reddish brown. Microscopic characters do not differ enough to help in separating these species and, frustratingly, "intermediates" abound (and, as long as I'm piling on the bad news, the maraschino odor is about the only thing separating this group from the Russula sororia group).

The acrid taste and funky odors make these mushrooms inedible.

Description:

Ecology: Mycorrhizal with conifers (Russula amoenolens is occasionally associated with hardwoods); growing alone, scattered, or gregariously; often found in grassy woodland areas; summer and fall (winter on the West Coast); widely distributed.

Cap: 4-10 cm across; convex, becoming broadly convex or flat, sometimes with a shallow central depression; sticky when fresh, but often dry when collected; light yellowish brown (Russula amoenolens) to dark yellowish brown or dark brown (Russula cerolens); the margin lined and pimpled at maturity; the skin peeling away easily at the margin, sometimes beyond halfway to the center.

Gills: Attached to the stem; close, crowded, or nearly distant; whitish to yellowish or pale orangish; often discoloring yellowish brown to brownish.

Stem: 3-7 cm long and up to 2.5 cm thick; white, discoloring brownish to yellowish brown (Russula amoenolens) or reddish brown (Russula cerolens); dry; more or less smooth.

Flesh: Whitish; unchanging.

Taste: Moderately to strongly acrid; odor waxy and reminiscent of maraschino cherries, almonds, or benzaldehyde.

Spore Print: Pale orange yellow.

Microscopic Features: 5.5-9 x 4.5-7 µ; broadly elliptical or, occasionally, nearly round; with spines up to 1 µ high, generally with few connecting lines, but sometimes with a few scattered connectors.

REFERENCES: R. amoenolens: Romagnesi, 1952. R. cerolens: Shaffer, 1972. (Shaffer, 1972; Weber & Smith, 1985; Kibby & Fatto, 1990; Phillips, 1991/2005; Roody, 2003.) Herb. Kuo 08050402, 01160504.

Further Online Information:

Russula amoenolens at MykoWeb
Russula amoenolens at Roger's Mushrooms

Russula cerolens

Russula amoenolens

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