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Suillus sibiricus

[ Basidiomycetes > Boletales > Suillaceae > Suillus . . . ]

by Michael Kuo

Suillus sibiricus was originally described from Siberia by Rolf Singer (1938)--and the name has since been variously applied by mycologists across the globe. In North America, "Suillus sibiricus" usually refers to the western equivalent of Suillus americanus, but it is unclear whether this western mushroom is actually distinct from Suillus americanus, or whether it actually corresponds to Singer's Siberian mushroom.

Both Suillus sibiricus and Suillus americanus are associated with 5-needle pines, and physical differences are not significant. Some authors attempt to separate the two mushrooms on the basis of the width of the stem (to 1.5 cm in Suillus sibiricus, but only to 1 cm in Suillus americanus); others attempt to describe differences in the yellowness of the species. However, Smith, Thiers & Miller (1965) discovered that

    depending on the amount of sunlight and the precipitation the color of individual fruiting bodies varied from one weather period to the next (even in a single day). During sunny weather the colors were bright yellow as in S. americanus . . . During rainy weather the colors became dilute . . . when the weather cleared and the sun came out, the color of the caps again became bright yellow.

If you ask me (you certainly don't have to) the two species, if they are distinct, are so by virtue of their mycorrhizal associations and range, rather than imagined differences in physical features. Suillus americanus associates with Pinus strobus; Suillus sibiricus associates with Pinus monticola and Pinus flexilis. Reports of Suillus sibiricus in eastern North America probably represent Suillus americanus, and rely on a second-hand account from Snell & Dick (1970; "reported from a tamarack bog in Ontario") and a single identification from Smith & Thiers (1971; "known in Michigan from the Yankee Springs Recreation Area in Barry County"), and probably result from over-emphasis of differences in morphological features that are, ultimately, variable (the same applies to reports of Suillus americanus from the Southwest).


Ecology: Mycorrhizal with western white pine (Pinus monticola) and limber pine (Pinus flexilis); growing scattered or gregariously; summer and fall; western North America.

Cap: 3-10 cm; convex becoming broadly convex or flat, sometimes with a broad central bump; sticky to slimy; dull to bright yellow; smooth or, more commonly, with scattered brownish to reddish brown fibers, streaks, scales, or patches; usually with partial veil remnants on the margin.

Pore Surface: Yellow becoming brownish yellow; usually bruising pinkish to cinnamon; pores angular and radially arranged, 1-2 mm across; tubes to 1.5 cm deep.

Stem: 4-11 cm long; up to 1.5 cm thick; equal; dull to bright yellow underneath brown to reddish brown glandular dots; sometimes with a fragile ring; staining reddish to purplish brown with maturity or on handling, especially toward the base.

Flesh: Yellow; not staining on exposure, or staining pinkish to reddish.

Odor and Taste: Not distinctive.

Chemical Reactions: Ammonia red on cap surface; red on flesh. KOH black on cap surface (sometimes after a red flash); black on flesh. Iron salts negative to grayish on cap surface; grayish to greenish on flesh.

Spore Print: Cinnamon brown.

Microscopic Features: Spores 8-12 x 3.5-4.5 µ; smooth; subfusoid.

REFERENCES: (Singer, 1938) Singer, 1945. (Singer, 1945; Smith & Thiers, 1964; Smith, Thiers & Miller, 1965; Smith & Thiers, 1971; Smith, 1975; Thiers, 1975; Smith, Smith & Weber, 1981; Arora, 1986; States, 1990; Phillips, 1991/2005; Both, 1993; Bessette, Roody & Bessette, 2000.) Herb. Kuo 08150717.

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


Suillus sibiricus

Suillus sibiricus

Suillus sibiricus

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Cite this page as:

Kuo, M. (2007, December). Suillus sibiricus. Retrieved from the MushroomExpert.Com Web site: