Major Groups > Boletes > Suillus > Suillus americanus


Suillus americanus

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

by Michael Kuo

"He lay flat on the brown, pine-needled floor of the forest, his chin folded on his arms, and high overhead the wind blew in the tops of the pine trees."

It's a good thing that Robert Jordan, the main character in Hemingway's For Whom the Bell Tolls, was in Spain for this first sentence of the novel. Because, if he were in eastern North America just after a late-summer rain, he would probably not have been able to see the bridge he was supposed to blow up, due to the hundreds of slimy yellow mushrooms growing among the pine trees.

Suillus americanus--sometimes called the "Chicken Fat Mushroom," and for good reason--can turn a forest of eastern white pine trees into a swamp of yellow slime. It can even turn your yard into a swamp of yellow slime, if there's a white pine tree within earshot. Distinguishing features include the yellow cap with reddish brown fibers and scales, and the thin stem, which bears glandular dots and a ring or ring zone.

The western species Suillus sibiricus is virtually identical; it grows under western five-needle pines.


Ecology: Mycorrhizal with eastern white pine; typically growing gregariously; summer and fall; widely distributed east of the Rocky Mountains (reported from the Southwest but possibly confused with Suillus sibiricus--assuming the two species are indeed distinct).

Cap: 3-10 cm; convex with an inrolled margin when young, but soon broadly convex to wavy to, well, rather shapeless; white to yellow brown veil tissue hanging from the margin; slimy; bright yellow, sometimes dingy yellow; frequently with reddish brown patches and markings.

Pore Surface: Yellow, darker with age; bruising reddish brown; pores angular and vaguely radially arranged (but not boletinoid), 1-2 mm across; tubes 7-10 mm deep.

Stem: 3-10 cm long; up to about 1 cm thick; frequently crooked or bent; with reddish brown glandular dots; occasionally with a ring or ring zone, but usually bare; frequently bruising reddish brown.

Flesh: Yellow throughout, staining purplish brown.

Odor and Taste: Not distinctive.

Chemical Reactions: Ammonia on cap surface with a pink flash, then red, then black; on flesh brown or black. KOH on cap surface black; on flesh dark brown. Iron salts on flesh olive.

Spore Print: Cinnamon to brown.

Microscopic Features: Spores 8-12 x 3-4 µ; smooth; fusoid.

REFERENCES: (Peck, 1887) Snell, 1944. (Coker & Beers, 1943; Smith & Thiers, 1964; Snell & Dick, 1970; Smith & Thiers, 1971; Grund & Harrison, 1976; Smith, Smith & Weber, 1981; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Both, 1993; Bessette, Roody & Bessette, 2000; Roody, 2003; McNeil, 2006; Miller & Miller, 2006; Kuo, 2007.) Herb. Kuo 09259402, 09019517, 09100101, 10030401.

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


Suillus americanus

Suillus americanus

Suillus americanus

Suillus americanus

Suillus americanus

Suillus americanus

Suillus americanus
A demonstration of how far from the host tree mycorrhizal mushrooms can appear; Suillus americanus grew in the flagged location, 44 feet from an eastern white pine.

© MushroomExpert.Com

Cite this page as:

Kuo, M. (2004, November). Suillus americanus. Retrieved from the MushroomExpert.Com Web site: