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

Summary:
The Tricholoma pessundatum group includes robust, viscid, reddish-brown species with reddish-spotted gills: Tricholoma pessundatum, T. albobrunneum (said to have a weaker odor, and a greasy cap finely streaked with darker lines), T. ustaloides (with a transient cortina and a sharply defined white zone at the top of the stem - see Lincoff(1) who questions North American occurrence but illustrates it, perhaps from Europe), T. flavobrunneum = fulvum (with pale yellow gills when young and yellow-tinted flesh in the stem), T. ustale (lacks a farinaceous odor), and Tricholoma muricatum Shanks 1996 (distinguished by a radially fibrillose cap with short grooves at the margin, orange-white gills, a brownish orange stem, and growth with pine, as well as microscopic characters).

Members of this group have been reported from OR (Trudell(4) -T. muricatum) and WA by Andrew Parker, pers. comm. Ovrebo(5) examined collections of T. pessundatum from MI and ON (both large and small spored variants in each). Bessette(5) say T. pessundatum occurs across northern N. America and extending south in the Appalachians - they show photographs from NY - but they also comment that "the potential for confusion with similar species makes it hard to assess the reliability of many reports". There are collections labeled as Tricholoma pessundatum at the University of British Columbia from BC and PQ, at the University of Washington from WA and MS, and at Oregon State University from AK. Shanks(2) refers to Tricholoma pessundatum (Fr.) Quel. as a European species associated with pines and it is possible that some collections of Tricholoma pessundatum are actually other members of the Tricholoma pessundatum group

Cap:
2.5-10cm across, when young convex with incurved margin, expanding to broadly convex, flat-convex or flat, often umbonate, margin often wavy or lobed; brown to dark reddish brown over most of surface with edge light yellowish brown or buff; viscid but dry when old, matted-fibrillose over center, elsewhere bald but generally with scattered minute, appressed fibrils, generally bald on edge, occasionally with scattered minute scales, (Ovrebo), very viscid, speckled over center with darker spots, (Bon(2))

Flesh:
0.7-1.8cm thick; light buff, often light brown near surface, in stem light buff and discoloring brown around wormholes, (Ovrebo)

Gills:
"typically notched or adnexed, but at times adnate or even free", close; white, but often developing sordid reddish or reddish brown spots and stains

Stem:
4-10(14)cm x 1-3cm, "equal or swollen or tapered below, solid, firm"; "whitish or developing sordid reddish or brownish stains or fibrils", especially over lower part

Veil:
absent

Odor:
"strongly farinaceous or like linseed oil", (Arora), mealy or pleasant (Schalkwijk-Barendsen)

Taste:
farinaceous (Lincoff(2))

Microscopic spores:
spores 4-6 x 2.5-4 microns, elliptic, smooth, inamyloid

Spore deposit:
white