Lactarius scrobiculatus var. canadensis

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

by Michael Kuo

The North American versions of "Lactarius scrobiculatus" are confusing and poorly documented. It may be the case that none of our North American mushrooms is truly identical to the European species named in the 19th Century by Elias Fries. In general, the mushrooms treated by North American authors as "Lactarius scrobiculatus" share the following features:

• A hairy cap margin, at least when young;
• Milk that is white but turns promptly yellow on exposure;
• A stem that has potholes;
• Elliptical spores with amyloid ridges that are less than .5 µ high.

But other features, including taste, cap color, hairiness, and spore print color, vary. Hesler & Smith (1979) question the documentation of Lactarius scrobiculatus proper in North America, and describe Lactarius scrobiculatus var. canadensis from the conifer forests of northern and montane North America. This variant has a whitish to olive buff cap that may become yellowish by maturity, mild or slightly acrid taste, a white or cream colored spore print, and fibrils on the cap that remain into maturity and often darken to brown.

Several field guide authors, including Smith (1975), Arora (1986), and Phillips (1991/2005), describe a western version of Lactarius scrobiculatus that is closer to the European species than Lactarius scrobiculatus var. canadensis. This mushroom is yellow from youth to maturity, and has a strongly acrid taste, a yellow spore print, and, in maturity, less prominent fibrils on the cap surface.

The European species Lactarius scrobiculatus is poisonous; I don't recommend experimenting with North American versions.

Description:

Ecology: Mycorrhizal with conifers; growing alone or gregariously; summer and fall; widely distributed in northern and montane regions of North America.

Cap: 4-10 cm; broadly convex with an inrolled and bearded margin when young; becoming shallowly vase-shaped, with the margin uplifted and smoother; slimy when young, but soon dry; covered with fibers that may darken to brownish, the fibers remaining visible in maturity; whitish at first, becoming olive buff or yellowish in age; without concentric zones of color.

Gills: Beginning to run down the stem; crowded; often forking near the stem; whitish; bruising or staining yellowish to pale brownish.

Stem: 3-11 cm long; 1-3 cm thick; equal; with many glazed, yellowish or brownish potholes; whitish; bruising and discoloring yellowish or brownish.

Flesh: Whitish; firm.

Milk: White, promptly turning yellow on exposure to air; scanty.

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

Spore Print: White or creamy.

Microscopic Features: Spores 7-9 x 5.5-7 µ; elliptical; ornamentation with prominences about 0.5 µ high; connecting lines amyloid, sometimes forming a partial reticulum.

REFERENCES: (Smith, 1960) Hesler & Smith, 1979. (Coker, 1918; Kauffman, 1918; Smith, 1975; Hesler & Smith, 1979; Smith, Smith & Weber, 1979; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Methven, 1997; Barron, 1999; McNeil, 2006; Miller & Miller, 2006.) Herb. Kuo 09120405.

Further Online Information:

Lactarius scrobiculatus var. canadensis in Hesler & Smith (1979)
Lactarius scrobiculatus at Roger's Mushrooms

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Cite this page as:

Kuo, M. (2004, September). Lactarius scrobiculatus var. canadensis. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/lactarius_scrobiculatus.html