Boletus zelleri (Murrill) Murrill
Zeller's bolete

Species account author: Ian Gibson.
Extracted from Matchmaker: Mushrooms of the Pacific Northwest.

Introduction to the Macrofungi


© Paul Dawson     (Photo ID #83780)


E-Flora BC Static Map

Distribution of Boletus zelleri
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Species Information

Chemical Reactions:
flesh stains greenish with application of NH4OH, (Bessette)
not distinctive (Bessette)
not distinctive (Bessette), slightly acidic (Lincoff(1))
spores 12-15 x 4-6 microns, subelliptic [somewhat elliptic] to subventricose [somewhat wider in middle], smooth, yellow, (Bessette), spores 12-15 x 4-5.5 microns, (occasional spore up to 24 microns), subelliptic to subventricose, smooth, pale yellow to pale ochraceous in KOH, ochraceous tawny in Melzer's reagent; basidia 4-spored, rarely 1-spored or 3-spored, 18-21 x 10-11 microns, clavate, colorless; hymenial cystidia rare to scattered to numerous, lacking in some fruitbodies, 40-85 x 10-13 microns, "clavate to obtusely fusoid to fusoid-ventricose to obscurely mucronate", colorless to rarely yellowish in KOH, thin-walled; cap cuticle "a trichodermium of free, septate, erect, inflated hyphal tips, often appearing similar to pileocystidia", the subterminal cell spherical to pear-shaped and the terminal cell somewhat pyramidal in outline, walls of cuticular hyphae often incrusted but not in spiral fashion, hyphae typically collapsing and appearing as a tangled mass of hyphal tips in older caps, appearing repent to interwoven (in B. chrysenteron, terminal hyphal cells are more or less equal in size and the hyphae are interwoven or more or less radially arranged, as well as being heavily spirally incrusted); stem cuticle interwoven, heavily incrusted, with laticiferous hyphae throughout; clamp connections absent, (Thiers), spores 12-16 x 4-5.5 microns, spindle-shaped to elliptic, (Arora)
Spore Deposit:
olive brown (Bessette, Thiers)
yes (Bessette)

Habitat and Range

Boletus chrysenteron has paler brown cap that becomes conspicuously areolate [cracked like dried mud] when old, with reddish flesh showing in the cracks, (Bessette). In deciding macroscopically between Boletus zelleri and B. chrysenteron / B. truncatus, a very dark pruinose cap means B. zelleri; a very areolate cap [with cracks like dried mud] with red in the cracks means B. chrysenteron or B. truncatus, but microscopic examination of the spores and cap cuticle is often necessary to distinguish B. truncatus and B. chrysenteron respectively from B. zelleri.
single, scattered, or in groups on ground or decaying wood in mixed conifer forest, (Bessette), late summer and fall (Miller), most prevalent in fall, but found at other times as well, (Trudell), spring, summer, fall, winter


Synonyms and Alternate Names:
Xerocomus zelleri (Murrill) Snell