Russula uncialis

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by Michael Kuo

Red species of Russula are confoundingly difficult to separate from one another, but Russula uncialis has enough distinguishing features to make it identifiable--perhaps even without microscopic analysis. To wit, these features are:

• Small to medium size (the cap is usually about an inch or two wide), and fragile stature.
• Pure white spore print and gills.
• Mild taste and nondescript odor.
• A dull pinkish red cap that is not mottled but sometimes has a darker center.
• A stem that is often flushed with the cap color.
• Habitat under hardwoods in eastern North America.

If you have matched all of these features, the odds are high that your mushroom is Russula uncialis; microscopic details (see below) will help confirm your identification.

Description:

Ecology: Mycorrhizal with hardwoods, especially oaks (but I have collected it in a lawn under shagbark hickory with no other trees nearby); growing alone or gregariously; often in grassy areas, and frequently found in lawns; summer and fall; eastern North America.

Cap: 2-6 cm; convex, becoming broadly convex to flat with a shallow depression; rather thin and fragile; sticky when wet and fresh, but soon dry; smooth or finely dusted; dull pinkish red to blood red or rose red; evenly colored, but often with a slightly darker center; the margin becoming lined at maturity; the skin peeling fairly easily, often more than halfway to the center.

Gills: Attached to the stem; close; a few forked near the stem; white; unchanging.

Stem: 1-5 cm long; up to 1 cm thick; more or less equal; smooth; white, often flushed with the cap color.

Flesh: White; unchanging on exposure.

Odor and Taste: Odor not distinctive; taste mild.

Spore Print: White.

Chemical Reactions: KOH on cap surface negative to yellowish or yellow; iron salts negative on stem surface.

Microscopic Features: Spores 7-9 x 5.5-7 µ; broadly elliptical; with warts projecting under 1 µ; connecting lines scattered and sparse, not forming reticula. Pileipellis a hyaline cutis with hyphal ends rounded to subacute or elongated-fusoid; pileocystidia absent.

REFERENCES: Peck, 1887. (Burlingham, 1915; Beardslee, 1918; Kauffman, 1918; Kibby & Fatto, 1990.) Herb. Kuo 06140304, 07120806.

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