Draft of Suillus pungens Thiers & A.H. Sm. for 2008/2009 EOL University Species Pages Initiative by Tom Bruns

Title: Draft For 2008/2009 Eol University Species Pages Initiative By Tom Bruns (Public)
Name: Suillus pungens Thiers & A.H. Sm.
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 Draft For 2008/2009 Eol University Species Pages Initiative By Tom Bruns (Public) [Edit]

Description status: Unreviewed

General Description:

Suillus pungens produces moderate-sized mushrooms, often in abundant troops under pines. Young mushrooms exhibit a distinctive array of colors. The youngest, immature mushrooms are pure white, but the pileus soon exhibits olivaceous or gray tones often in irregular slimy patches. As the pileus matures (and as it is exposed to light) it often develops orangish steaks and eventually becomes a yellowish-brown color typical of many species in the genus. The stipe is white, exhibits no ring (annulus), and is covered by fine glandular dots. The later are initially cinnamon colored, but become black with age and often bleed together to make small streaks. The name “pungens” refers to the the supposedly pungent odor, but this does not seems to be detected by everyone.

Diagnostic Description:

The detailed description of the species provided below is from Mykoweb Boletes of California section: and was originally derived from Thiers 1975^1^ book California Mushrooms.

Pileus 4-14 cm broad when expanded, obtusely convex to convex when young, becoming broadly convex to plano-convex with age; surface viscid to glutinous during all stages of development, glabrous but sometimes appearing obscurely streaked from gluten when older; color when young white to olive (“deep grayish olive” to “grayish olive” to “citrine drab”) with splotches or irregularly shaped areas colored pale olive (“pale olive-buff” to “olive-buff”), frequently strongly variegated with a mixture of light and dark colors, when older unchanging or becoming reddish brown (“ochraceous-tawny”), sometimes a mixture of all the pigments mentioned above; margin incurved and with a cottony roll of white tissue when young, becoming naked and merely decurved with age. Context 1-2 cm thick, white and unchanging in young basidiocarps, frequently changing to yellow (“pinard yellow”) when older. Taste harsh, subnauseous, and weakly acid; odor strong, pungent.

Tubes up to 1 cm in length, adnate when young, becoming decurrent to subdecurrent with age; color when young whitish to pale buff (“cartridge buff”) with conspicuous whitish droplets that become brown to ochraceous when dried, with age changing to near yellow (“colonial buff”) and finally to dark yellow (“honey yellow”); pores 1-1.5 mm broad, not radially arranged, unchanging when bruised, angular.

Stipe 3-7 cm long, 1-2 cm thick at the apex, equal to tapering at the base to sometimes subventricose, solid; surface dry, glabrous, strongly punctate, glandulae large, irregular in outline, reddish at first then becoming brownish, background whitish to more or less concolorous with the tubes when young, becoming yellow (“pinard yellow” to “massicot yellow”) with age, unchanging when bruised; no annulus. Context white, unchanging when exposed.

Spore print brown. Spores 9.5-10 X 2.8-3.5 µm, hyaline in KOH, smooth, thin-walled, ellipsoid to subcylindric in face view, inequilateral in profile.

Basidia 33-36 X 8-10 µm, hyaline, clavate, contents granulose in KOH, four-spored. Hymenial cystidia 43-79 X 7-10 µm, rare to scattered, abundant on the pores, typically occurring in massive clusters, dark brown in KOH, cylindric to subclavate, incrusted, occasionally hyaline, thin-walled.

Tube trama hyaline, divergent to subparallel, hyphae 3-5 µm wide. Pileus trama interwoven, homogeneous. Pileus cuticle differentiated as an ixotrichodermium, staining brown in KOH, hyphae 4-5 µm wide. Stipe cuticle with clusters of cystidia similar to those found in the hymenium. Clamp connections absent.

Chemical reactions KOH-context vinaceous, tubes red, pileus cuticle black, stipe cuticle pale vinaceous; NH4OH-context very pale vinaceous, tubes bright red; FeSO4-context gray, tubes dark gray to black, stipe cuticle light gray.

Habit, habitat, and distribution Solitary to gregarious in humus under Monterey pine. This is often the most abundant Suillus in the San Francisco Bay Area, and although it is usually found under Monterey pine, a few collections have been made under knobcone pine. The type collection was made on the campus of San Francisco State University in San Francisco, where it occurs in abundance during the fall and winter seasons. It is one of the few species of Suillus that continues to fruit sporadically throughout the year.

Observations This species is distinctively characterized by the very noticeable color changes occurring in the pileus as it develops. In most instances the young pilei are pure white, as development continues they next become dark gray, and finally at maturity they typically change to rust brown in color. The tubes, when young, are almost white but become yellow with age. If the humidity is high, there is usually an abundance of whitish droplets on the hymenophore, at least during the young stages. The ring of cottony veil tissue on the margin of the pileus is very pronounced during the younger stages but, as is often the case in the genus Suillus, it disappears with age. Suillus pungens has been misidentified as S. placidus because of the white color of the young basidiocarps and the droplets of exudate. The pallid to white colors, the cottony roll of veil tissue, and the unpleasant taste and odor distinguish it from S. granulatus and S. albidipes.

Edible, but not choice.


S. pungens is known only from California, where it is the most common species of Suillus in urban settings with Monterey pine. It is also abundant in native forests of Monterey and Bishop pine from approximately Mendocino south, and on Santa Cruz and Santa Rosa islands in the Bishop Pine Forests. Its spores have been found in the Eastern Sierra Nevada through sequence analysis of seedling bioassays^2^ and the species has been seen fruiting in the Sierra Nevada with Lodgepole and Ponderosa pine, but it does not appear to be common in these habitats.


It is an ectomycorrhizal associate of two and three-needle pines, and is especially common with Monterey and Bishop pine. Individual mycelia of S. pungens are known to be large, obtaining sizes of greater than 300 square meters 3, and presumably get that way though vegetative growth. Following disturbance, however, it colonizes primarily by spore^4^, and the effectiveness of it spore dispersal and colonization are likely to be the underlying cause of its abundance in urban settings.

Look Alikes:

At maturity many Suillus species in the “granulatus” group can easily be confused. In California all identifications of S. granulatus are probably this species, as no sequence-confirmed cases of the S. granulatus are known from the region.


Like other Suillus species it is an edible mushroom, but this species is not considered to be choice.


1 Thiers, H.D. 1975. California Mushrooms. New York: Hafner Press, division of Macmillan Publishing Co. 261.
2 Rusca, T.A., P.G. Kennedy, and T.D. Bruns. 2006. The effect of different pine hosts on the sampling of Rhizopogon spore banks in five Eastern Sierra Nevada forests. New Phytol.
170 : 551–560.
3 Bonello, P., T.D. Bruns, and M. Gardes. 1998. Genetic structure of a natural population of the ectomycorrhizal fungus Suillus pungens. New Phytol., 138: p. 533-542.
4 Bruns, T.D., J. Tan, M.I. Bidartondo, T.I. Szaro, and D. Redecker. 2002. Survival of Suillus pungens and Amanita francheti ectomycorrhizal genets was rare or absent after a stand-replacing wildfire. New Phytol. 155: 517-523

Description author: Tom Bruns (Request Authorship Credit)