Summary:
Tricholoma imbricatum is told from other Tricholomas by its generally robust stature, a dry, dull reddish brown to cinnamon brown or dark brown cap that is fibrillose to fibrillose-scaly and often has short grooves along the margin, pale buff gills that discolor or spot brownish, a solid stem, absence of a veil, and an association with conifers especially pine. Heilmann-Clausen(1) compared a California ITS sequence to two European ITS sequences and found them quite deviant, enough that a separate species might be represented by the Californian material.

Cap:
4-12(20)cm across, convex with inrolled margin, becoming convex-umbonate to flat or uplifted; dark brown to brown or cinnamon brown; dry, with flattened fibrils that may break up into scales when old, "especially toward margin (which may be obscurely ribbed)", (Arora), 5-10cm across, convex to obtuse when young, the margin inrolled, broadly convex to obtusely umbonate when old, sometimes remaining broadly conic; dull reddish brown, at times becoming dull cinnamon brown; dry, innately fibrillose to fibrillose-scaly, at times the cuticle rimose [cracked] along margin, margin downy, "sometimes the margin ribbed at least for a short time", (Smith), 2-10cm across, "when young, obtuse, obtusely conic or convex-umbonate with an incurved margin, expanding to obtusely conic, convex, broadly convex or convex-umbonate", often with wavy margin; when young light dull brown ("cinnamon brown" Ridgway(1) color) over the center and light buff on margin, when mature dark dull brown overall or lighter on edge; dry, densely matted-fibrillose or rarely bald over center, "appressed-fibrillose to appressed or slightly recurved-squamulose elsewhere, the extreme margin occasionally striate and rarely naked", (Ovrebo)

Flesh:
thick, firm; white, (Arora), compact, firm; slowly becoming reddish when bruised or cut, (Smith), 0.5-1cm thick; white or pale buff, often light brown near cap surface, in stem "buff overall or often yellowish brown or watery brown at the base", (Ovrebo)

Gills:
"adnexed, notched or even adnate, close"; "white or tinged flesh-color", often discoloring brown when old, especially on edges, (Arora), sinuate to adnexed, close, broad; "pallid at first, gradually becoming grayish vinaceous or at times with sordid reddish spots"; edges even or becoming slightly eroded, (Smith), "arcuate on buttons, emarginate to sinuate when mature", close, subgills numerous but not arranged in distinct tiers, gills 0.2-0.7cm broad; "whitish buff, discoloring light yellowish brown to dull brown in spots or more or less diffused"; edges entire, (Ovrebo)

Stem:
4-12cm x 1-3cm, solid, firm, equal or swollen in lower part with tapered, sometimes rooting base; white or buff becoming brownish when old, especially over lower part (top usually pallid); dry, fibrillose or minutely scaly when old, (Arora), 4-9(11)cm x 1-2cm at top, club-shaped but becoming nearly equal, solid; "whitish at first but soon brownish to reddish brown from base upward"; unpolished, top white-pruinose, (Smith), 3.5-6cm x 0.5-1.5cm, equal, ventricose or obclavate [reverse club-shaped], the base abruptly narrowed, stem solid; buff overall when young, when mature the top remaining buff but lower part darkening to dark buff or light brown ("cinnamon brown" Ridgway(1) color), often watery brown at the base, occasionally discoloring watery brown or yellowish buff in spots; silky fibrillose and with loosened surface fibrils projecting, often slightly pruinose at top, (Ovrebo)

Veil:
absent (Arora)

Odor:
mild or faintly farinaceous (Arora), mild to slightly farinaceous (Smith), absent (Ovrebo)

Taste:
mild to slightly farinaceous (Smith), absent to slightly peppery, (Ovrebo), sometimes slightly bitter aftertaste (Lincoff(1))

Microscopic spores:
spores 5-7 x 3.5-5 microns, elliptic, smooth, inamyloid, (Arora), spores 5.5-7 x 4-4.5 microns, elliptic, smooth, inamyloid, with a large central oil droplet; basidia 4-spored, 24-28 x 7-8 microns, colorless in KOH; pleurocystidia and cheilocystidia not differentiated, (Smith), spores 5.7-7.6 x 4.3-5.2 microns, elliptic to broadly elliptic in face and side views, smooth, inamyloid, thin-walled; basidia 4-spored or rarely 2-spored, 27-34 x 6.7-7.6 microns, clavate, colorless; pleurocystidia and cheilocystidia absent; clamp connections absent, (Ovrebo)

Spore deposit:
white (Arora, Ovrebo)

Notes:
Ovrebo(5) examined collections from ID, MI, ON, and Sweden. The distribution (in North America) is northern North America and CA according to Lincoff(2). There are collections from BC and CA deposited at the University of British Columbia. There are collections at the University of Washington from WA, OR, ID, and AK. Bessette(5) show photographs from WA, AZ, CO, and NM.

EDIBILITY

not recommended because easy to confuse with Tricholoma pessundatum group (Arora)