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Lactarius montanus

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

by Michael Kuo

This mushroom is the western North American version of the eastern Lactarius uvidus. It associates with conifers and willows in wet montane ecosystems, and features a stockier stem and a drier cap surface than the eastern North American species. Like its eastern counterpart it has a cap that turns green when a drop of KOH is applied, and copious white milk that stains tissues lilac purple.

Lactarius uvidus var. montanus is a former name.


Ecology: Mycorrhizal with conifers and with willows, in wet montane ecosystems; summer and fall; Rocky Mountains, Cascade Mountains, and the Sierra Nevada.

Cap: 3-11 cm; convex with an incurved margin when young, becoming flat or shallowly depressed; sticky when very fresh but soon dry; bald; finely rugged; brownish lilac to lilac brown or brownish purple or purplish gray; without concentric zones of color, or occasionally with faint zones.

Gills: Broadly attached to the stem or beginning to run down it; close; whitish to creamy; stained lilac to purple (eventually brownish) by the milk where damaged.

Stem: 3-10 cm long; 1-3 cm thick; club-shaped, becoming more or less equal with maturity; dry or slightly sticky when fresh; without potholes; whitish to purplish buff; often stained yellow in places, especially near the base; bruising and discoloring lilac to purple.

Flesh: White; staining lilac when sliced.

Milk: White; copious; staining tissues lilac to purple.

Odor and Taste: Odor fragrant or not distinctive; taste not distinctive, or faintly resinous.

Spore Print: Yellowish.

Chemical Reactions: KOH green on cap surface.

Microscopic Features: Spores 8-12 x 6-9 µ; broadly ellipsoid; ornamentation mostly under 0.5 µ high; connectors sometimes forming partial reticula. Macropleurocystidia up to about 100 x 10 µ; fusiform; pinched one or more times near the apex. Pileipellis an ixocutis.

REFERENCES: (Hesler & Smith, 1979) Montoya & Bandala, 2003. (States, 1990; Evenson, 1997; Methven, 1997.) Herb. Kuo 08160708. Herb. DBG: RMNP 2008-055, 2008-056, 2008-059, 2008-067.

This site contains no information about the edibility or toxicity of mushrooms.


Lactarius montanus

Lactarius montanus

Lactarius montanus

Lactarius montanus

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