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Lactarius controversus

[ Agaricomycetes > Russulales > Russulaceae > Lactarius . . . ]

by Michael Kuo

This Lactarius is a mycorrhizal partner with aspens and willows across northern and montane North America. I find it under quaking aspen and big-toothed aspen in northern Michigan and Colorado. Distinctive features include the pink gills, the whitish cap that sometimes develops indistinct zones of pale pink or pale purple, the unchanging white milk, and the acrid taste.


Ecology: Mycorrhizal with species of Populus (especially quaking aspen and big-toothed aspen) and Salix; growing alone or gregariously--or sometimes in dense troops; summer and fall; widely distributed in northern and montane North America.

Cap: 7-30 cm; at first convex with an inrolled, slightly hairy margin; becoming flat with a central depression, or vase-shaped, with an even and bald margin; slimy to sticky when fresh, but soon dry; rugged with appressed fibers; whitish overall, but often with faint zones of pinkish or purplish, especially near the margin.

Gills: Attached to the stem or beginning to run down it; thin; close or nearly crowded; sometimes forking near the stem; pinkish to pale pink.

Stem: 2.5-10 cm long; 1.5-4 cm thick; more or less equal, or tapering to the base; sticky when fresh, but soon dry; usually without potholes, but occasionally with a few; bald; eventually becoming hollow; whitish.

Flesh: White; unchanging on exposure; fairly firm.

Milk: White; unchanging on exposure to air; not staining tissues; not staining white paper.

Odor and Taste: Odor not distinctive, or pleasantly fragrant; taste slowly moderately to strongly acrid.

Chemical Reactions: Cap surface negative to pale yellowish with KOH.

Spore Print: Creamy white or pale pinkish.

Microscopic Features: Spores 6-7.5 x 4.5-5 µ; ellipsoid; ornamentation under 0.5 µ high, as amyloid warts and ridges usually forming partial or nearly complete reticula. Pleuromacrocystidia and cheilomacrocystidia scattered; not projecting; inconspicuous; aciculate to fusiform, with apical constrictions; to about 45 µ long. Pileipellis an ixocutis.

REFERENCES: Persoon, 1800 (Fries, 1821; Saccardo, 1887; Kauffman, 1918; Hesler & Smith, 1979; Smith, Smith & Weber, 1979; Arora, 1986; Lincoff, 1992; Evenson, 1997; Methven, 1997; Heilmann-Clausen et al., 2006; McNeil, 2006.) Herb. Kuo 09019501, 09130407, 07250606, 08160710, 09140806.

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Lactarius controversus

Lactarius controversus

Lactarius controversus

Lactarius controversus

Lactarius controversus

Lactarius controversus

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Kuo, M. (2011, March). Lactarius controversus. Retrieved from the MushroomExpert.Com Web site: