Summary:
Features include 1) a viscid to glutinous, appendiculate cap that is whitish to orange-cinnamon to reddish brown or dark brown and may turn more vinaceous or brownish when bruised, 2) white to yellowish flesh, 3) angular, yellow to pale ochraceous pores that darken (but do not change when bruised), 4) a white stem that becomes yellow at the top and stains darker when bruised or old, 5) glandular dots on the stem that may be rare or scattered, 6) a white to purplish brown or reddish brown membranous (not gelatinous) veil that stains vinaceous gray and that leaves remnants on the cap and sometimes an annular zone on stem, and 7) growth under conifers especially pines. Nguyen(3) provide molecular and other evidence to show that Suillus borealis is a synonym of Suillus brunnescens. Because considerable extra information is contained in the S. borealis descriptions, those are included too.

Chemical Reactions:
flesh stains pink with application of KOH (Bessette), flesh stains vinaceous with application of KOH and grayish with FeSO4, (Bessette for S. borealis)

Odor:
not distinctive (Bessette), slight (Smith for S. borealis)

Taste:
not distinctive (Bessette), mild (Smith for S. borealis)

Microscopic:
spores 6.5-9 x 2.5-3.5 microns, oblong, smooth, colorless to pale honey yellow, (Bessette), spores 6.6-8.8 x 2.8-3.2 microns, oblong, smooth, pale yellow-brown in Melzer''s reagent, colorless to dingy yellow brown in KOH, thin-walled; basidia 4-spored, 18-25 x 4.4-6.6 microns, clavate, colorless to yellowish in KOH and often with amorphous granules, in Melzer''s reagent pale yellowish to brownish; pleurocystidia 40-70 x 8-12 microns, "in fascicles with the bundles surrounded by incrusting pigment more or less bister in KOH", subcylindric to fusoid-ventricose, content colorless to dingy yellow-brown, smooth or with some incrusting debris, thin-walled, cheilocystidia similar but more with brown content and adhering debris, so numerous at times as not to appear clustered; epicutis of cap a gelatinous trichodermium of hyphae 4-9 microns wide and containing numerous dark brown granules in KOH, the walls soon almost completely gelatinized; caulocystidia similar to cheilocystidia; clamp connections none, (Smith), spores 6-9 x 3-5 microns, subcylindric [nearly cylindric] to subelliptic [somewhat elliptic], smooth, colorless, (Bessette for S. borealis), spores 7-8 x 2.8-3 microns, narrowly oblong, smooth, colorless to yellowish in KOH, only slightly more yellowish brown in Melzer''s reagent; basidia 4-spored, many with amorphous red content in KOH; pleurocystidia scattered, 38-50 x 8-12 microns, subfusoid, clavate or cylindric, content and area surrounding the cluster vinaceous-red in KOH and some clusters vinaceous-gray in a few specimens; cap epicutis of hyphae 4-9 microns wide, "appressed on cap surface (probably a collapsed trichodermium), gelatinous and as revived in KOH with numerous minute granules in the gelatinous matrix and along the hyphae (some of these vinaceous in KOH but most are merely yellowish)", in Melzer''s reagent the granules yellowish; caulocystidia "in clusters or scattered and similar to pleurocystidia"; clamp connections none, (Smith for S. borealis)

Spore Deposit:
brown (Bessette), brown (Bessette for S. borealis), pale "orange-cinnamon" when fresh, "cinnamon-buff" after moisture escapes (Ridgway colors), (Smith for S. borealis)

Notes:
Suillus brunnescens is found at in least OR, ID, CO, and CA, (Bessette). The distribution is extended by including S. borealis. As Suillus borealis, S. brunnescens is found in the northern Rocky Mountains and the Pacific Northwest (Bessette), ID (Smith(36)), northern CA (rare - Thiers), WA (Buck McAdoo, Eugene Butler, pers. comm.), OR (Oregon State University Herbarium), and BC (Michael Beug, pers. comm.).

EDIBILITY

yes (Bessette), yes, when gluten has been removed, (Bessette for S. borealis)

Synonyms and Alternate Names:
Gymnomyces brunnescens "(Singer & A.H. Sm.) Trappe,"
Martellia brunnescens Singer & A.H. Sm. Mem. Torrey