Lactarius argillaceifolius

[ Basidiomycetes > Russulales > Russulaceae > Lactarius . . . ]

by Michael Kuo

This milky cap is common and widely distributed, but can be frustratingly difficult to identify with certainty, since a number of lilac drab species (including Lactarius uvidus) are fairly common in North America. The defining features of Lactarius argillaceifolius are:

• The color of the gills: creamy when young; later dingy cinnamon.
• The drab lilac color of the cap.
• The off-white (rather than pure white) color of the milk.
• The brownish (rather than purplish) staining of the cap and gills by the milk.

As with many species of Lactarius, the staining can take quite some time to develop; be sure to wait at least 30 minutes before making a decision.

Lactarius argillaceifolius is widely distributed in North America and has several varieties--principally, variety argillaceifolius (described below) and variety megacarpus, distinguished by cap size, spore ornamentation, gill color, and West-Coast distribution (see the right-hand column).

Lactarius argillaceifolius is potentially poisonous; do not consider it for the table.

Description:

Ecology: Mycorrhizal with oaks; growing alone or gregariously; spring, summer and fall; widely distributed east of the Rocky Mountains.

Cap: 4-15 cm; convex becoming flat or shallowly vase-shaped; drab cinnamon to drab lilac brown; evenly colored (without zones); sticky to slimy.

Gills: More or less crowded; cream colored when young; staining slowly brown where cut; dingy clay color to cinnamon in age.

Stem: 6-9 cm long; 1.5-3.5 cm thick; tapering to base; pale or brownish in age; dry or slightly slimy; smooth.

Flesh: White, discoloring faintly tan.

Milk: Whitish cream, not changing; staining gills brownish.

Odor and Taste: Odor not distinctive to mildly fragrant; taste mild to slowly acrid.

Spore Print: Pinkish buff.

Chemical Reactions: KOH on cap surface erasing pigments to pale orange.

Microscopic Features: Spores 8-10 x 7-8 µ; broadly elliptical; ornamentation with prominences 0.5-1 µ high; amyloid connecting ridges scattered, sometimes forming broken reticula.

REFERENCES: Hesler & Smith, 1979. (Hesler & Smith, 1979; Smith, Smith & Weber, 1979; Weber & Smith, 1985; Arora, 1986; Canduso, Genari & Ayala, 1994; Methven, 1997.) Herb. Kuo 06119505, 09020101, 05300403, 01150505, 07100702.

Further Online Information:

L. argillaceifolius var. argillaceifolius in Hesler & Smith (1979)
L. argillaceifolius var. megacarpus in Hesler & Smith (1979)
L. argillaceifolius var. dissimilis in Hesler & Smith (1979)
Lactarius argillaceifolius var. megacarpus at MykoWeb

Differs from var. argillaceifolius as follows:

Cite this page as:

Kuo, M. (2007, September). Lactarius argillaceifolius. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/lactarius_argillaceifolius.html