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Lactarius rubrilacteus

[ Basidiomycota > Russulales > Russulaceae > Lactarius . . . ]

by Michael Kuo

This western North American species of Lactarius features a brownish orange cap, scanty red to purplish red milk, gills that are dull orange from the beginning, and green-staining surfaces. It is associated with Douglas-fir and various pines from the Rocky Mountains westward. Lactarius deliciosus var. areolatus can appear very similar; it is also orangish, it bruises green, and its milk is scanty. However, its milk is orange, rather than purplish red--and it lacks pleuromacrocystidia.


Ecology: Mycorrhizal with Douglas-fir and with pines; growing alone or gregariously; summer and fall in the Rocky Mountains; fall and winter along the West Coast; distributed from the Rocky Mountains westward. The illustrated and described collection is from California.

Cap: 4-9 cm; convex at first, with an inrolled margin; becoming broadly convex to centrally depressed, with an uplifted margin, or shallowly vase-shaped; sticky when fresh; bald, but finely rugged; brownish orange, with slightly paler zones; staining dirty green.

Gills: Beginning to run down the stem; close; short-gills frequent; pale dirty orangish, becoming darker orange with age; staining and bruising dirty green.

Stem: 2-4 cm long; 1-2 cm thick; tapered to the base; bald; without potholes; dry; dull orangish; staining dirty green; basal mycelium whitish.

Flesh: Whitish; fairly firm; staining pink to purplish when sliced.

Milk: Very scant; red to purplish red; staining surfaces red to purplish red.

Odor and Taste: Odor not distinctive; taste slightly acrid, or not distinctive.

Chemical Reactions: KOH negative on cap surface.

Spore Print: Pale yellow.

Microscopic Features: Spores 8-10 x 5.5-6.5 µ; ellipsoid; ornamentation consisting of amyloid warts and ridges extending about 0.5 µ high, forming partial reticula. Hymenial macrocystidia to about 70 µ long; subfusiform. Pileipellis an ixocutis.

REFERENCES: Hesler & Smith, 1979. (Smith, Smith & Weber, 1979; Arora, 1986; States, 1990; Phillips, 1991/2005; Methven, 1997; Miller & Miller, 2006; Nuytinck et al., 2006; Nuytinck et al., 2007; Trudell & Ammirati, 2009.) Herb. Kuo 01151502.

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Lactarius rubrilacteus

Lactarius rubrilacteus

Lactarius rubrilacteus

Lactarius rubrilacteus

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Kuo, M. (2015, May). Lactarius rubrilacteus. Retrieved from the MushroomExpert.Com Web site: