Tricholoma robustum
chocolate tricholoma
Tricholomataceae

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

Introduction to the Macrofungi

Photograph

© Michael Beug     (Photo ID #17486)


Map

E-Flora BC Static Map

Distribution of Tricholoma robustum
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Species Information

Summary:
Features include 1) relatively large size, the cap 7-15cm across, 2) a chestnut-brown to reddish date brown cap that is greasy, tomentous-scaly at least at centre, appressed fibrous at the margin, 3) a stem that tapers at the base, the top part white to brownish, and grainy, below the ring a lighter red brown and fibrous-scaly, 4) growth in pine woods, and spores 4.5-5.5(6) x 3-3.5 microns. Tricholoma focale has been considered a synonym of Tricholoma robustum and this was the stance of the Online Fungorum, accessed January 31, 2008. The same site, accessed May 3, 2016, gives only Tricholoma focale sensu Riva p.p. (1998), Galli (1999) as a synonym. Moser(1) keeps them separate on the basis of a chestnut- to reddish date brown cap and spores 4.5-5.5(6) x 3-3.5 microns for Tricholoma robustum, as opposed to foxy red, orange-brownish cap with margin almost cinnabar and spores 3-4.5 x 2.25-3 microns for Tricholoma focale. In North America the name Tricholoma robustum was used for what was described in 1989 as Tricholoma zelleri. 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. (For other differences see SIMILAR section: as Paul Kroeger is describing them, he has found Tricholoma focale, Tricholoma zelleri, and Tricholoma robustum in the Pacific Northwest including BC).
Cap:
7-15cm across, "chestnut- to reddish date brown"; "greasy, tomentous-scaly at least at centre, adpressed fibrous at margin"
Gills:
deeply sinuate, broad, thick, detachable all together; pale, finally spotted/dirty, (Ricken)
Stem:
10-12cm x 1.5-3cm, tapering at base; "apex white to brownish, grainy, below ring lighter red brown fibrous-scaly", (Moser), 6-7cm x 1.5-2.0cm, more or less equal or ventricose, reddish-ferruginous below the ring, at the apex pale. darkening, with pale squamules, annulus inferior, sheathing, thick [rigonfio], and pale, (Ricken)
Odor:
none (Ricken)
Taste:
mild (Ricken)
Microscopic spores:
spores 4.5-5.5(6) x 3-3.5 microns, (Moser), spores elliptic 4-5/3 microns; basidia 20-25 x 5-6 um. REMARKS distinguished from the previous species [Tricholoma focale] by the .
Notes:
From the above, there is some evidence for T. robustum in WA and BC.
EDIBILITY

Habitat and Range

SIMILAR SPECIES
Tricholoma focale is similar but T. robustum has less bright colors, a cap that is not fibrillose-striate (T. focale has darker fibrillose streaks), and a thick ring, (Ricken). T. focale has a dry, fibrillose-scaly, drab brown cap, stem likewise drab, dry and fibrillose, and Tricholoma zelleri has a bronze to coppery, smooth and sometimes +/- viscid or shiny cap, often whitish at the margin, smooth but sometimes breaking into scales, odor of raw potato, gills with a decurrent tooth, spotting ochraceous brown, and surfaces staining ochraceous then brown, whereas Tricholoma robustum has bronze to olivaceous bronze cap with innate black radiating fibrils especially over center, margin usually dark, surface smooth but merely lubricous to dry, sometimes breaking into scales, gills whiter and more crowded than the others and attached straight across, spotting less and then yellow then ochraceous or orangy brown, surface staining yellow to yellow-orange then ochraceous, odor of green corn or soil Actinomyces [musty], persisting after drying, (Paul Kroeger, pers. comm.)
Habitat
pine woods (Moser), especially in conifer woods (Ricken)