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

Summary:
Features include 1) often massive size, 2) a viscid cap that lacks distinct scales and is yellow (especially when young) or reddish brown to vinaceous brown or cinnamon or with green tinges, 3) a cap margin with hanging veil remnants, 4) yellow flesh that is greenish in the stem base, 5) large, yellow pores that stain brownish, 6) a massive, yellow stem that is equal or narrows downward and stains rusty brown from handling, and 7) a membranous annulus often stained reddish cinnamon on the underside from a gelatinous outer layer. Suillus imitatus var. viridescens is considered a synonym and has more conspicuous green tinges. The cap of the latter was described originally in Smith(10) as "by maturity at times showing dark green spots as if stung by an insect or flushed olive dark green over wide areas" and rarely the surface blackish green to dingy bluish green. The pore surface of var. viridescens was not described as turning blue or green but the stem surface was sometimes green apart from the apex and the stem flesh was sometimes green or blue when cut (Smith(10)).

Suillus ponderosus is found at least in WA, OR, and CA, along the Pacific coast, (Smith), ID (collections at Oregon State University), and BC (in Redhead, and collection at the University of British Columbia).

Cap:
5-15cm, convex becoming broadly convex to nearly flat when old; "yellow, especially when young, bright reddish brown to vinaceous brown or cinnamon with a yellow margin at maturity, sometimes with green tinges or green overall when young or mature"; bald, glutinous to viscid, somewhat streaked under gluten; margin often with hanging veil remnants, (Bessette), 9-25cm, convex to flat or wavy and irregular when old; "at times deep vinaceous brown to testaceous, sometimes cinnamon or toward margin yellow streaked with cinnamon"; bald or with veil remnants only near margin, viscid, "somewhat streaked beneath the pellicle"; margin with hanging veil remnants, (Smith), ''reddish to dark brownish lavender ("vinaceous-brown" to "testaceous") to sometimes brown ("cinnamon") or yellow toward the margin and streaked with cinnamon'' (colors in quotation marks from Ridgway), (Thiers(1))

Flesh:
"yellow, unchanging or becoming pale vinaceous in spots when exposed", (Bessette), thick, firm; yellow, unchanging, very seldom with larval tunnels even when old; in stem pale yellow, greenish in base where cut, "with a faint pink tinge above as well as in pileus finally", (Smith)

Pores:
1-3mm, subangular [somewhat angular]; yellow at first, becoming dull yellow when old, staining brownish when bruised; tube layer up to 1.5cm thick, decurrent to subdecurrent, (Bessette), 1-3mm in longest dimension, subangular; yellow staining brownish; tube layer up to 1.5cm thick (in 25cm cap), decurrent, dull yellow, (Smith), tubes unchanging when exposed (Thiers(1))

Stem:
6-14cm x 2.5-6cm, narrowing downward or nearly equal down to tapered base, solid; yellow above annulus, pale yellow to yellow below annulus when young, becoming dull rusty brown below annulus when old or when handled; dry, reticulate above annulus and bald to obscurely reticulate below annulus when young; partial veil "membranous, pale yellow to yellow or orange-yellow with reddish brown tints, coated with gluten; annulus membranous, superior, glutinous and often stained reddish brown on the underside", (Bessette), 9-14cm x 3-6cm, narrowing downward, with pointed base at times, solid; bright yellow above annulus and soon sordid rusty in lower part from handling; reticulate above annulus from decurrent tubes, less reticulate below annulus; "annulus membranous, superior, often stained reddish cinnamon on under side from a gelatinous outer layer", (Smith), reticulate above annulus from decurrent tubes, sometimes obscurely reticulate below annulus; annulus is bright orange to orange yellow in young fruitbodies, (Thiers(1))

Chemical Reactions:
cap surface stains black with application of KOH, flesh stains vinaceous with application of KOH and gray with FeSO4, (Bessette)

Odor:
acidic or not distinctive (Bessette), sharply acidulous, (Smith)

Taste:
not distinctive (Bessette), mild, (Smith)

Microscopic:
spores 8-12 x 4-5 microns, elliptic to subfusoid, smooth, colorless to olive-yellow, (Bessette), spores 8-10(12) x 3.8-5 microns, elliptic to subfusoid or nearly oblong, smooth, pale ochraceous in Melzer''s reagent, colorless to olive-yellowish in KOH; basidia 4-spored, 26-31 x 7-10 microns, clavate, colorless in KOH; pleurocystidia 29-72 x 5-8 microns, cylindric to clavate, or crooked, at times subfusoid, colorless or with dark brown pigment as revived in KOH, single or in clusters and with dark yellow-brown pigment in and around base of cluster, cheilocystidia similar to pleurocystidia; cap epicutis a gelatinous layer of interwoven colorless to pale ochraceous hyphae 2-4 microns wide and branched not infrequently; caulocystidia 50-70 x 6-12 microns, cylindric to clavate or fusoid, scattered and in clusters, colorless to dark brown in KOH and some incrusted in addition, "amorphous dark brown pigment around clusters and distributed in caulohymenium (as revived in KOH)"; clamp connections absent, (Smith)

Spore Deposit:
brown (Bessette), snuff brown, (Smith)