E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Features include 1) smooth, viscid to glutinous cap that is red-brown to yellow-brown, 2) unchanging flesh and pores that are white to pale yellow, 3) conspicuous whitish sheathing annulus which is often viscid or with a lavender band or layer externally, 4) prominent glandular dots during all stages on a white to pale yellow upper stem, and 5) growth under conifers. "Suillus luteus is the most widespread species in the world, occurring in the Northern and Southern Hemisphere. It is native to Europe, where it associates with P. sylvestris and P. nigra, but it has also been introduced into North and South America, Asia, and Australasia with P. sylvestris"; it has been recorded with several other pine species internationally, (Nguyen).

Suillus luteus is widely distributed through North America (Bessette). The exact RANGE is uncertain because the name has been applied to almost any Suillus with an annulus, (Smith(34)), and Smith(36) noted in 1965 "In the light of our more restricted concept of S. luteus its presence in the Pacific Northwest needs further verification." It was found in MI (Smith(34) in 1964), and has been reported from BC (in Redhead), WA, OR, (both vouchered at University of Washington and at Oregon State University), ID (K. Chadwick, pers. comm.; vouchered at Oregon State University), CA (Thiers), NS (Grund), and also Europe and Asia (Breitenbach).

Cap:
5-12cm, rounded, becoming broadly convex to nearly flat when old; "dark reddish brown to cinnamon-brown, yellow-brown or ochre"; "smooth, viscid to glutinous when moist, often shiny when dry"; margin appendiculate [with hanging veil remnants], (Bessette), 5-12cm, hemispheric to obtuse at first, broadly convex to flat when old; "raw sienna" to "Sudan brown" (Ridgway colors) or tawny to bister (color variable in yellow-brown to red-brown series); bald and viscid but at times somewhat streaked under gluten, cap pellicle separable, (Smith(34)), typically reddish brown to dark reddish brown or chestnut-brown, but ranging sometimes toward yellow-brown or rusty-brown, especially when old, and sometime streaked, (Arora), with a slight umbo at times; violet highlights in damp weather (Lincoff(1))

Flesh:
"white to pale yellow, not staining blue when cut or bruised", (Bessette), white or tinted pale yellow especially near tubes and stem; in stem colored as surface or whitish, (Smith(34)), white or pale yellow, often slightly pinky toward stem, (Phillips)

Pores:
1-2 per mm, angular; "whitish to pale yellow when very young", yellow to dark yellow or olive-yellow when old, unchanging when bruised; tube layer 0.4-1.5cm thick, (Bessette), 3 per mm, when old 1-2 per mm, yellow at first but becoming dark dotted, surface with a sheen; tubes 0.3-0.7cm thick, gradually shorter toward cap margin, adnate to subdecurrent, ''at first whitish to pale yellow, at length "honey yellow" to "old gold"'' (Ridgway colors), unchanging when cut, (Smith(34)), tubes same color as pores (Arora)

Stem:
3-8cm x 1-2.5cm, nearly equal, solid; white when young, becoming pale yellow at top and "often developing dingy purplish or brownish tones" toward the base when old; with glandular dots and smears at least above annulus; partial veil "white, with dull purple to purplish gray tones on the underside, forming an often large and flaring or sleeve-like annulus that is white with purple or dark purple tones and is gelatinous in humid weather", (Bessette), (3)4-8cm x 1-2.5cm, equal or narrowing at base, solid; pale yellow above annulus; glandular dotted above the annulus and beneath the sheath, typically peronate [sheathed] by "whitish veil up to the membranous often reflexed, rather persistent annulus", "veil membranous and with a gelatinous purplish zone on the under side or outer surface in humid weather, or exterior layer of sheath purplish gray in age", (Smith(34)), pinkish to brown glandular dots and smears (Arora), pale yellow dots that turn reddish brown (Lincoff(1))

Chemical Reactions:
cap cuticle dull dark gray with application of KOH, grayish olive with FeSO4; flesh pinkish then pale blue-gray with KOH, grayish blue to olive with application of FeSO4, (Bessette)

Odor:
not distinctive (Bessette, Smith(34))

Taste:
not distinctive (Bessette), pleasant (Smith(34))

Microscopic:
"spores 7-9 x 2.5-3 microns, nearly oblong, smooth, pale brown", (Bessette), spores 7-9 x 2.5-3 microns, smooth, with pronounced colorless sheath, more or less oblong, inamyloid, nearly colorless in KOH; basidia 4-spored, 14-18 x 4-5 microns, yellowish in KOH; pleurocystidia "in scattered to rare bundles surrounded by bister debris", "when isolated 20-35 X 5-7 microns and narrowly clavate, content usually bister as revived in KOH", cheilocystidia "similar, but tube edges often a mass of bister incrustation obscuring the cystidia"; cap cuticle of gelatinous filaments 2-4 microns wide, forming a tangled trichodermium, colorless in KOH and pale yellowish in Melzer''s reagent; stem with numerous fascicles of caulocystidia, the clusters bister in KOH; clamp connections not seen, (Smith(34)), spores 7-10 x 3-3.5 microns, (Lincoff(1))

Spore Deposit:
brown, (Bessette), ''"sayal brown" to "clay color" dull cinnamon when moisture has escaped'' (Ridgway colors), (Smith(34)), brown to dull cinnamon (Arora)