Summary:
Tricholoma zelleri is distinguished by a viscid, orange to orange-brown cap splashed with olive or yellow, rusty spotted gills, a stem that is pallid above the membranous ring and usually somewhat scaly or with orange or brown stains below, and a potato-like to slightly farinaceous odor. The cap often has a somewhat metallic (coppery or bronzy) appearance. Tricholoma zelleri is synonymized by some authors with Tricholoma focale (see that species for a discussion of those two names and Tricholoma robustum). The name robustum has been used for this species - in the original description of Armillaria zelleri, Smith says that S. Zeller published an account of it under the name A. robusta [in Zeller(1)]. He says however that 1) descriptions of T. robustum and T. focale do not characterize either as viscid so T. zelleri cannot be referred to either, and 2) he had found a very similar fungus with a dry cap in Olympic National Park Washington which appears to be T. robustum. Tricholoma zelleri (if that is the correct name) is common in the Pacific Northwest.

Cap:
5-10(15)cm across, subconic to obtuse with inrolled margin at first, becoming broadly umbonate or nearly flat; '"orange" on disc and "olive-ocher" near the margin (orange to sordid greenish yellow from disc outward), colors usually quite mixed and variable (similar to those of Tricholoma aurantium)' [Latin name in italics]; glutinous to viscid at first (merely moist when old after heavy rain), fibrillose beneath gluten and when old frequently minutely scaly with distinct agglutinated patches of fibrils, usually with adhering patches of veil tissue along the margin, (Smith), bronze to copper smooth and sometimes +/- viscid or shiny cap, often whitish at margin, (Paul Kroeger, pers. comm.), 4-15cm across, convex becoming flat or broadly umbonate; "bright orange to yellow-orange, or orange-brown, or sometimes splashed with olive-green"; viscid when moist, margin at first hung with veil remnants, (Arora)

Flesh:
cap flesh thick 1.5cm near stem); white, slowly changing to orange-brownish where bruised or around worm holes; stem pallid within, (Smith), thick; "white, slowly bruising orange-brown", (Arora)

Gills:
"adnate or slightly adnexed at first, developing a decurrent tooth", close to crowded (128+/- reaching stem), 2-3 tiers of subgills, gills narrow but becoming moderately broad (0.8cm); pallid when young ("tilleul buff"), soon staining or becoming rusty brownish or spotted dull rust color; edges even or slightly serrate, (Smith), "close, adnate or notched"; "white, developing rusty-orange-brown stains", (Arora)

Stem:
(4)7-13cm x 1-2(3)cm at top, "tapered to a more or less pointed base, solid but usually hollowed by grubs"; "sheathed up to the ragged submembranous annulus by a pallid sheath which very soon becomes dull orange and breaks up to leave scales or zones of orange fibrils", eventually somewhat glabrescent [becoming somewhat bald], "surface above the annulus merely fibrillose-furfuraceous and whitish", (Smith), 4-13cm x 1-3cm, usually tapered downward, solid; "pallid above the ring, usually somewhat scaly or with orange or brown stains below"; dry, (Arora)

Veil:
annulus ragged, submembranous, whitish on upper surface, usually orange on underside, (Smith), "white, membranous, forming a flaring or ragged, median to superior ring" on stem which frequently collapses when old, (Arora)

Odor:
slightly farinaceous, (Smith), potato-like (Paul Kroeger, pers. comm.), strongly rancid-farinaceous (Arora), rather like fresh meal but with an added pungent, somewhat metallic component, (Ammirati, who however says T. focale may the correct name)

Taste:
slightly farinaceous (Smith), strongly rancid-farinaceous, (Arora), rather like fresh meal but with an added pungent, somewhat metallic component, (Ammirati, who however says T. focale may the correct name)

Microscopic spores:
spores 4-5(5.5) x 3.5 microns, elliptic, smooth, inamyloid, colorless; basidia 4-spored; pleurocystidia and cheilocystidia none; cap trama "homogeneous beneath a thin gelatinous layer which is easily removed in sectioning", inamyloid, "the hyphae just below this layer dull orange to reddish in KOH", (Smith), spores 4-5.5 x 3-4 microns, elliptic, smooth, inamyloid, (Arora), spores 6-7.5 microns x 3.7-5 microns (Zeller(1))

Spore deposit:
white (Arora)

Notes:
It has been reported specifically from BC (Bandoni(1)), and from WA and OR by Smith(15). There are collections labeled as this species from BC at the University of British Columbia.

EDIBILITY

"not edible because of the unpleasant taste and smell" (Arora)

Synonyms and Alternate Names:
Armillaria zelleri D.E. Stuntz & A.H. Sm.