|Major Groups > Boletes > Suillus > Suillus placidus|
by Michael Kuo
This easily identified Suillus features a bald white cap and a slender stem that develops conspicuous glandular dots and smears that contrast with the stem surface. It is apparently exclusively associated with eastern white pine, and can be found throughout the range of the host tree (northeastern North America, south through the Appalachians). Pale or faded specimens of Suillus granulatus can be very similar but usually have stems that develop yellow shades and are slightly more thick, proportionally.
Boletus albus Peck (1872) is probably the same mushroom, according to Snell (1933, 1970).
Thanks to Susan Moody for collecting, documenting, and preserving Suillus placidus for study; her collection is deposited in The Herbarium of Michael Kuo.
Ecology: Mycorrhizal with Pinus strobus (eastern white pine); growing alone, scattered, or gregariously; summer and fall; fairly widely distributed in northeastern North America, west to the Dakotas and southward with the Appalachian Mountains--corresponding with the natural range of the host tree (see the map on the linked page); also found in Europe where Pinus strobus has been introduced. The illustrated and described collection is from Minnesota.
Cap: 4-9 cm; convex becoming broadly convex or nearly flat; sticky when fresh; white when young, darkening slightly with maturity to yellowish white or nearly yellowish; bald or nearly so; in age the gluten sometimes drying brownish.
Pore Surface: White when very young, becoming dull yellow; not bruising; pores becoming angular, about 1-2 per mm; tubes to 1 cm deep.
Stem: 4-9 cm long; 5-12 mm thick; more or less equal above a somewhat tapered base; sticky when fresh; whitish underneath conspicuous, large glandular dots and smears that are initially pinkish but soon darken to reddish brown or brown; without a ring; basal mycelium white.
Flesh: Whitish to yellowish; often staining slowly pinkish to reddish when sliced, especially in the stem base.
Odor and Taste: Not distinctive.
Chemical Reactions: Ammonia on cap surface pink, then black to dull red or purple; on flesh pink to red, becoming purplish or grayish. KOH on cap surface pink, becoming black or purple; on flesh pink.
Spore Print: Cinnamon brown.
Microscopic Features: Spores 7-9 x 2-3 µ; smooth; subfusiform; hyaline to yellowish in KOH. Pleurocystidia cylindric to clavate; to about 65 µ long. Cheilocystidia conspicuous; bundled; to about 80 x 8 µ; clavate to capitate; smooth or sometimes somewhat encrusted near the base; pinkish red to reddish brown in KOH. Caulocystidia capitate to swollen-capitate. Pileipellis an ixocutis.
REFERENCES: (Bonorden, 1861) Singer, 1945. (Saccardo, 1888; Snell, 1933; Coker & Beers, 1943; Smith & Thiers, 1964; Snell & Dick, 1970; Smith & Thiers, 1971; Grund & Harrison, 1976; Smith, Smith & Weber, 1981; Weber & Smith, 1985; Breitenbach & Kränzlin, 1991; Phillips, 1991/2005; Lincoff, 1992; Both, 1993; Barron, 1999; Bessette, Roody & Bessette, 2000; McNeil, 2006.) Herb. Kuo 09121403.
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Cite this page as:
Kuo, M. (2014, November). Suillus placidus. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/suillus_placidus.html