SUILLUS CAERULESCENS Smith and Thiers, Contr. Toward a Monogr. of N. Am. Sp. of Suillus p. 36. 1964

Illustrations: See Microfiche No. 40
Smith, A. H., and H. D. Thiers, A Contribution Toward a Monograph of North American Species of Suillus, pl. 10.

Pileus 6-14 cm broad, broadly and shallowly convex when young, becoming plano-convex to plane with age; surface viscid, usually with patches of agglutinated fibrillose tomentum appearing as scattered squamules or streaks, frequently glabrous with age; color uniformly dull reddish to reddish brown ("vinaceous" to "ochraceous-tawny") on the disc and yellowish ("ochraceous-buff") toward the margin, squamules near the margin colored brown ("cinnamon"); margin at times appendiculate with partial-veil remnants. Context 10-20 mm thick, pale yellow ("ivory yellow"), unchanging or becoming dingy pink ("avellaneous"). Taste and odor mild.

Tubes 6-10 mm long, adnate to short decurrent, when young yellow ("primrose yellow" to "sulfur yellow" to "deep colonial buff"), unchanging or darkening slightly with age, staining dingy vinaceous brown ("avellaneous") when bruised; pores 1.5-2 mm long, ▒1 mm wide, yellow ("honey yellow"), very irregularly angular, sometimes radially aligned but not always so, occasionally appearing compound.

Stipe 2.5-8 cm long, 2-3 cm thick at the apex, tapered toward the base or apex, or equal, solid; surface reticulate at the apex, glabrous to punctate above the annulus, glabrous to appressed fibrillose to matted fibrillose below, not glandular dotted, staining brown when handled, concolorous with the tubes above the annulus, becoming duller and often dingy brown below; annulus fibrillose, pallid to white but soon discoloring as the pileus, not strongly gelatinous. Context yellow (like the pileus margin), slowly staining blue in the base when exposed.

Spore print dingy cinnamon. Spores 8-11 X 3-5 Ám, smooth, hyaline to ochraceous in KOH, pale orange buff to cinnamon buff in Melzer's, ellipsoid in face view, obscurely inequilateral in profile, thin-walled.

Basidia 20-30 X 5-8 Ám, four-spored, clavate, yellowish in KOH and Melzer's. Hymenial cystidia of two types, the first 35-70 X 5-8 Ám, cylindric to clavate with brown pigment around base of cluster, with content brown to hyaline in KOH, the other 22-28 X 5-8 Ám, fusoid-ventricose and isolated to scattered, with refractive granules.

Tube trama hyaline, gelatinous, somewhat divergent near the subhymenium, with an obscure to distinct central strand, numerous large contorted laticifers present staining dark brown in KOH. Pileus trama interwoven, homogeneous, occasional laticifers present. Pileus cuticle up to 400 Ám thick, differentiated as an ixotrichodermium with hyphae 8-15 Ám wide, superimposed on a basal layer with mostly unbranched hyphae 3-7 Ám wide, hyaline to pale ochraceous in KOH. Caulocystidia similar to hymenial cystidia. Clamp connections not seen.

Chemical reactions HN03-context and tubes yellow; H2SO4-context yellow, tubes reddish; FeS04-context and tubes gray; guaiac-cuticle, context and tubes blue.

Habit, habitat, and distribution Solitary to gregarious in soil under Douglas fir. Often abundant in the northern coastal forests, but not yet known from the higher elevations or from the more southerly portions of the state. Indications are that, at least in California, Douglas fir is the exclusive mycorrhizal host. Characteristically appearing early in the fall, S. caerulescens persists throughout the fall and winter season.

Material studied Del Norte County: Thiers 17645, 17731. Humboldt County: Thiers 13763, 14092, 14180, 17746, 24134, 24353. Marin County: Madden 625, 695; Thiers 11976, 24643. Mendocino County: Motta 58; Sundberg 68; Thiers 8439, 8751, 9042, 9511, 9630, 10532, 10703, 11054, 14115, 14609, 21519, 23062, 24204. Napa County: Sundberg 84; Thiers 10168, 10803, 11892. Nevada County: Thiers 26906. San Mateo County: Thiers 11820, 11916, 17909, 18176. Santa Cruz County: Largent 363, 389; Thiers 10782, 10793, 12035, 12299, 17937, 18533. Shasta County: Thiers 18207, 21586, 21673. Sonoma County: Thiers 9415, 10235, 12501, 18034. Trinity County: Thiers 10852.

Observations The large size of the cap, the glutinous and streaked pileus surface, which is never very darkly colored, the boletinoid arrangement of the tubes, the white to pallid annulus that is not glutinous, and the blue discoloration developing in the context of the basal part of the stipe are characters that distinguish this bolete. It is most likely to be confused with and certainly appears closely related to S. ponderosus, which, however, has an annulus that is not only glutinous but also colored bright yellow to reddish brown or orange, and a pileus that is typically glabrous and more deeply colored.

Edible, but of inferior quality.

Online edition addendum

Other Descriptions and Photos: The Fungi of California

The Boletes of California
Copyright © 1975 by Dr. Harry D. Thiers
Additional content for the online edition © 1998 by Michael Wood, Fred Stevens, & Michael Boom
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