SUILLUS BOREALIS Smith, Thiers, and Miller, Lloydia 28:123. 1965

Pileus 7-11 cm broad when mature, convex when young, becoming broadly convex to plano-convex to plane or shallowly depressed at maturity, often with undulating or highly irregular outlines when very old; surface very viscid to glutinous, glabrous, but some pilei appearing streaked from gluten; color brown ("orange-cinnamon" to "vinaceous-cinnamon" to "cinnamon"), sometimes dark brown ("Mikado brown" to "Verona brown") on the disc, fading to pale brown ("light pinkish cinnamon" to "pinkish buff") on the margin; margin strongly incurved, typically strongly appendiculate when young, but glabrous in some pilei when older, sterile. Context 1-2 cm thick, when young whitish, becoming yellow with age, changing to yellow when exposed in young basidiocarps. Taste and odor mild.

Tubes up to I cm long, shorter near the margin, adnate to broadly and shallowly depressed, yellow ("old gold"), unchanging when exposed; pores ▒1 mm broad, angular, concolorous, unchanging when bruised.

Stipe 2-4 cm long, 1.5-2 cm thick at the apex, equal, solid to stuffed; surface dry, glandulae not strongly apparent when young but becoming so with maturity; color white when young, becoming reddish brown ("tawny" to "ochraceous-tawny"), frequently bright yellow at the apex, sometimes staining pale brown at the base; no annulus. Context white to yellow, unchanging when exposed.

Spore print brown. Spores 6-8.5 X 3-5 Ám, hyaline in KOH, yellowish in Melzer's, subellipsoid to subcylindric, smooth, thin-walled.

Basidia 25-31 X 8-11 Ám, clavate, four-spored, hyaline. Hymenial cystidia rare to absent on sides of tubes, abundant to crowded on the pores, dark brown in KOH and Melzer's, heavily incrusted, occasional hyaline clusters with only the base discoloring in KOH; individual cystidia 30-54 X 7-13 Ám, cylindric to clavate, thin-walled.

Tube trama strongly divergent from a distinct mediostratum, subgelatinous in KOH, hyaline. Pileus trama interwoven, homogeneous, hyaline to pale brown in KOH. Pileus cuticle differentiated as a layer of interwoven to tangled hyphae 3-4 Ám wide, gelatinous, hyaline to pale brown in KOH, rust brown in Melzer's. Stipe cuticle differentiated as a layer of gelatinous hyphae with numerous large fascicles of cystidia staining dark brown in KOH. Clamp connections absent.

Chemical reactions KOH-context vinaceous; FeSO4-context gray.

Habit, habitat, and distribution Gregarious to subcespitose in soil in mixed pine--oak woods. Known only from a single collection made under pines in the vicinity of Willow Creek in northern California. This species was originally described from Idaho but is now known from throughout the Pacific northwest. It appears to be associated with five-needle pines, but further data are necessary before its mycorrhizal host can be accurately determined.

Material studied Humboldt County: Thiers 14266.

Observations This species is characterized by the presence of a veil but no annulus, the very dark brown color of the pileus, and the white to pallid stipe, at least when young, with obscure glandulae on the surface. There are no other species in California with which it is likely to be confused. In other areas it might be confused with S. luteus, but that species has a distinct annulus. Suillus pseudogranulatus, a species known only from the southeastern portion of the United States, also seems to be somewhat similar, but is much paler in color and also has an annulus or at least a fibrillose zone on the stipe.

Edibility unknown.

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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