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Russula species 01

by Michael Kuo, 26 September 2024

I find this beautiful russula every year in the Midwest's oak-hickory forests, in July and August. The striking rose pink cap color is consistent from year to year, as are the other features separating this apparently unnamed species: yellowish orange mature gills and spore print, mild taste, a white stem—and, under the microscope, spores with fairly isolated warts and an absence of pileocystidia.

In North American literature I find no good matches for this russula. Murrill's Russula cremeirubra comes close, but should have a creamy cap with pale red shades, along with pale yellow gills and spore print (additionally it was described in association with live oaks in Florida). In Europe, Russula velenovsky and, especially, Russula laeta are similar oak-loving species that differ in the shades of red on their caps; also it is highly unlikely that a temperate-zone mycorrhizal species would occur on both continents.

Description:

Ecology: Mycorrhizal with oaks and/or hickories in oak-hickory forests; growing gregariously; July and August; distribution uncertain. The illustrated and described collections are from Illinois.

Cap: 3.5–9 cm; convex, becoming broadly convex or nearly flat, with a shallow central depression; bald; sticky when young but soon dry; bright rose pink ("carnation pink"); the skin peeling about halfway to the center; the margin becoming widely lined.

Gills: Attached to the stem; close or, in age, nearly distant; short-gills absent or few; white when young, becoming dull medium yellow-orange; not staining.

Stem: 3–6 cm long; 1–2 cm thick; tapered to base; dry; bald; white; not bruising; becoming cavernous near the base; basal mycelium white.

Flesh: White; not changing when sliced.

Odor and Taste: Not distinctive.

Chemical Reactions: KOH on cap surface erasing pigments. Iron salts on stem surface negative or slightly pinkish.

Spore Print: Yellow-orange.

Microscopic Features: Spores 6–9 x 6–8 µm; broadly ellipsoid or subglobose; ornamentation as mostly isolated amyloid spines 0.5–1 µm high, with occasional connecting lines, not forming reticula. Basidia 38–42 x 9–11 µm; clavate; 4-sterigmate. Pleurocystidia 40–70 x 8–12 µm; widely lageniform; smooth; thick- or thin-walled; hyaline in KOH. Pileipellis a turf of mostly upright elements 2–3 µm wide, smooth or slightly encrusted, hyaline in KOH; terminal cells cylindric with subacute or merely rounded apices; pileocystidia not found.

REFERENCES: (Burlingham, 1915; Kibby & Fatto, 1990; Knudsen et al., 2018; Læssøe & Petersen, 2019.) Herb. Kuo 07282202, 08012401.

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Spore print

Spores

Pleurocystidia

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Kuo, M. (2024, September). Russula species 01. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/russula_species_01.html