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

Summary:
Section Pluteus. Diagnostic features are a large dark cap, close gills with fuscous edges, an off-white stem overlaid with dark brown fibrils, a pinkish brown spore deposit, growth usually on conifer wood, oval-subelliptic spores, most pleurocystidia with 2-5 apical or subapical horns, the horns sometimes forked, and profuse clamp connections on the cap cuticle hyphae. |Pluteus laricinus, described from a single collection in Michigan, is considered a synonym by Justo(4). In comparing the descriptions of both by Banerjee and Sundberg, spore measurements are smaller in P. laricinus, (4.4)5-6.4 x 4.6-5 microns, and there are other differences in the way the microscopic characters are described. Gills are white, becoming pale pink and edges grayish near cap margin, the stem is described as slender and (in the Latin description) 0.2cm thick at top. It is only slightly enlarged downward, whitish and not darkening, and has faint avellaneous pruina near base. (Stem length is 3cm and cap width 1.5cm.) (Banerjee(1)). DNA does differ somewhat from collections labeled as P. atromarginatus and Pacific Northwest DNA tends, according to D. Miller, pers. comm., to be closer to P. laricinus than to European collections. If the synonymy does not hold, Pluteus laricinus may be a usable name for Pacific Northwest material, even though the type is not typical morphologically. |The Phillips description is for P. atromarginatus (Kon.) Kuehner.

Collections were examined from WA, OR, ID, MI, NY, TN, Austria, and Czechoslovakia, (Banerjee). Collections were examined from CA, OR, and TN, (Justo(4)). There are collections from BC at the Pacific Forestry Centre and the University of British Columbia. Breitenbach(4) give the distribution as North America, Europe, and Asia.

Cap:
4-12cm across, obtuse to convex when young, expanding to flat or with a low broad umbo; "benzo brown", "mummy brown" to black; at times radially streaked with blackish fibrils on a "drab" ground color, sometimes with minute appressed squamules, moist, not hygrophanous, margin often somewhat rimose, (Banerjee), 3-10cm across, "convex-flattened; blackish brown with darker streaks and fibrils; smooth to slightly squamulose at center", (Phillips), butyraceous [buttery] when moist (Breitenbach)

Flesh:
thick, cottony, soft; white, in stem also white, (Banerjee), white (Phillips)

Gills:
flat-arcuate, close, broad (up to 0.9cm), 1-2 tiers of subgills; white becoming dull pink to "pinkish buff", margin dark brown to blackish brown (+/- cap color), (Banerjee), crowded, broad; "pallid then pink-salmon with edges dark brown", (Phillips)

Stem:
5-12cm x 0.5-1cm at top, equal to evenly widening downward, somewhat flattened, solid; off-white overlaid with dark brown fibrils, not darkening when old, (Banerjee), 5-10cm x 0.5-1cm, "white with dark brown fibers on surface", (Phillips)

Veil:
[absent]

Odor:
sweetish or fungoid (Banerjee after Singer 1956), pleasant (Phillips)

Taste:
not unpleasant, fungoid, (Banerjee after Singer 1956), pleasant (Phillips)

Microscopic spores:
spores 6-7.8(9) x 4.4-5.6 microns, oval-subelliptic to lacrymoid [tear-shaped], smooth, nearly colorless, thin-walled, content granular, hilar appendix conspicuous; basidia 4-spored, (17)28-35 x 7-8.2 microns, colorless; pleurocystidia very abundant, 50-85(105) x 12-20(27) microns, fusoid-ventricose, colorless, "thick-walled, with 2-5 apical or subapical horns, horns sometimes forked, some pleurocystidia with fewer or no horns are occasionally found", cheilocystidia in fascicles (22)35-58(80) x 10-20(27) microns, "clavate to balloon-shaped, with dark brown content, all thin-walled", some colorless elements are also found intermixed with the colored elements; cap cuticle of narrow (3-6 microns wide) septate hyphae and occasionally of some broader (10-25 microns wide) interwoven hyphae, both with dark brown content; clamp connections profuse on cap cuticle hyphae, (Banerjee), spores 6.5-8 x 4.5-5 microns, elliptic, smooth, pleurocystidia have horns at apex, (Phillips)

Spore deposit:
pinkish brown (Banerjee), brownish pink (Phillips)