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Summary: The distinctive features are 1) growth under larch and 2) the hollow lower stem (not found in other Suillus species). Other features are 3) a cap that is suede-like with dark brown and yellow-brown fibrils and scales, 4) yellow flesh that does not turn blue, 5) pores that are angular, somewhat radiating, yellow to olive yellow, and unchanging in color, 6) stem that is yellow and reticulate in the upper part without glandular dots, and cap-colored in lower part, 7) a veil that leaves whitish hanging remnants on the cap margin and often a slight annulus on the stem, and 8) microscopic characters that include clamp connections. Suillus cavipes is found in eastern Canada south to NY, west to the northern Rocky Mountains and AK, (Bessette). It is common throughout the northern hemisphere wherever larch occurs, including OR, ID, and MT, (Arora), ID, MA, MI, NY, and OR, (Smith(34)), WA (collections at the University of Washington), BC and NB (Redhead, collections at the University of Washington), NS (Grund), and Europe and Asia (Breitenbach).
Cap: 3-10cm, rounded to convex, becoming nearly flat, occasionally with rounded umbo; covered with dark brown to yellow-brown fibrils and scales with an almost suede-like texture; dry; margin with hanging dry whitish veil remnants, (Bessette), 3-10(12)cm, obtuse to convex expanding to nearly flat or at times with obtuse umbo; "cinnamon rufous" to "tawny" or "orange cinnamon" (Ridgway colors), rarely ocher yellow or paler, "moist to dry but not viscid, densely tomentose to fibrillose-squamulose", the tips of the fibrils often pallid; margin usually with adhering veil remnants, (Smith), "typically dark brown to reddish-brown to orange-brown or tawny (rarely paler), the margin and/or tips of the fibrils often paler", (Arora), dull yellow to reddish, reddish brown to dark reddish brown, rarely ocher-yellow, (Smith(35)), reddish brown usually, but at times can be pale yellowish brown, (Trudell)
Flesh: yellow, not turning blue when cut or bruised, (Bessette), soft; white to yellowish when old, not turning blue when bruised, (Smith(34)), white to yellowish, in stem sometimes pinkish (Phillips)
Pores: 0.5-1.5mm or more wide, angular, sometimes radiating; "pale yellow to olive-yellow, unchanging when cut or bruised"; tube layer 0.2-0.6cm thick, (Bessette), "0.6-1.0mm wide and 1-1.5mm or more radially, angular, radiating, simple to compound; yellow when young"; tube layer 0.3-0.5cm thick, decurrent, pale yellow to greenish yellow, more olive-ochraceous when old, (Smith(34))
Stem: 3-9cm x 1-2.5cm, nearly equal or widening slightly downward, typically hollow in the lower half at maturity; yellow on upper part, colored like cap on lower part; more or less reticulate at top, lacking glandular dots or smears; veil present, often leaving a slight annulus, (Bessette), (3)4-9cm x (0.5)0.8-1.5(2)cm, usually narrowed in lower part and enlarged at top, nearly equal at times, solid in upper part, hollow in the base; usually colored as cap or a paler shade, top yellow at times; lower part "decorated with veil remnants at first but these soon vanishing, at times with a slight annulus", (Smith(34)), veil fibrillose-cottony, white, forming a thin, fragile, fibrillose annulus on stem and/or leaving remnants on cap margin, (Arora)
Chemical Reactions: cap surface black with application of KOH (Bessette)
Odor: not distinctive (Bessette, Smith(34))
Taste: not distinctive (Bessette, Smith(34))
Microscopic: spores 7-10 x 3.5-4 microns, narrowly oval to ventricose, smooth, pale brown, (Bessette), spores 7-10 x 3.5-4 microns, narrowly oval to ventricose, smooth, nearly colorless in Melzer's reagent and greenish transparent in KOH; basidia 4-spored, 18-35 x 4-5 microns, colorless in KOH; pleurocystidia scattered to numerous, 42-56 x 6-10 microns, subcylindric to fusoid-ventricose, colorless, thin-walled, cheilocystidia similar or obventricose; cap cuticle a deep loose trichodermium of hyphae 8-15 microns wide, the cells more or less equal or narrowed at cross walls, colorless in KOH, yellow in Melzer's reagent; clamp connections present, (Smith(34)), spores 7-10 x 3.5-4 microns, elliptic to spindle-shaped, (Arora)
Spore Deposit: brown, (Bessette), dark olive-brown when moist, (Smith(34)), dark olive to brown (Arora), olivaceous (Phillips)
Habitat / Range
scattered or in groups on ground under larch in forests and bogs, (Bessette), gregarious to cespitose [in tufts] under larch, (Smith(34)), late summer and fall, (Miller)
Suillus lakei lacks hollow stem, is associated with Douglas-fir, and lacks clamp connections. Other boletes under larch include Suillus grevillei, S. ochraceoroseus, and S. viscidus: these also lack clamp connections.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2017. E-Flora BC:
Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for
Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
21/03/2018 9:36:50 AM
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