Solitary or gregarious in mossy lawns, on moss-covered
tree trunks, among vegetable debris under deciduous trees (e.g. Fagus),
and on fallen needles under coniferous, particularly Picea. Autumn. Common in nemoral part of the area, much rarer further north.Rarely recorded in Norway but fairly common around the Oslo fjord.
Pileus 5-15 mm across, conical to broadly conical or campanulate, with
age becoming convex, and often with an umbo, glabrous, hygrophanous,
translucent-striate, sulcate, at first often dark black-brown
at the centre with pale brown to beige or almost whitish
margin, generally with a marked margin between the darker
and the pallid parts of the pileus, then fairly dark brown
at the centre, paler to beige towards the margin, fading
to pale grey or pale greyish brown with pallid to whitish
margin. Lamellae 17-26 reaching the stipe,
ascending, narrow, narrowly adnate, white to cream or pale
grey, often with a pale yellowish shine, the edge concolorous
or very weakly coloured pale yellow, easiest seen in young
specimens and near the margin of the pileus. The yellow
edge often not perceptible in older specimens. Stipe
15-60 x 0.5-1 mm, terete, equal, hollow, straight to curved
below, and even somewhat flexuous, not very fragile, experienced
as fairly firm, glabrous except for the pruinose apex, greyish
to brownish, often olivaceous brown at the apex and darker
brown below; the base covered with coarse, white fibrils.
Odour usually strong, disagreeable,
raphanoid or reminiscent of raw potato.
Basidia 21-29 x 7-9 µm, clavate,
4-spored, with sterigmata 5-6 µm long. Spores 7.5-10
x 4-5 µm, Q 1.5-2.2, Qav 1.8-1.9, pip-shaped to somewhat elongated, smooth, amyloid. Cheilocystidia
19-65 x 9-27 µm, forming a sterile band, sessile to stipitate, ellipsoid to
clavate, obpyriform or subglobose, densely covered
with warts or evenly spaced, cylindrical excrescences 0.5-3 x 0.5-1 µm. Pleurocystidia
similar. Lamellar trama dextrinoid. Hyphae of the pileipellis
3-27 µm wide, densely covered with warts or short excrescences 1.5-6 x 1-1.5 µm. Hyphae of the cortical layer of the stipe
2-5 µm wide, covered with scattered, short, cylindrical excrescences 0.5-2 x 0.5-1 µm; terminal cells not inflated. Clamp connections present in all tissues.
Microphotos of cheilocystidia, basidia and hyphae of the pileipellis
is readily placed in Sect. Filipedes
on account of the cheilocystidia and a combination of the
colours of pileus and stipe. It is a very variable species
(see Maas Geesteranus 1992: 66), and probably often misidentified or overlooked. Identification
usually should cause little difficulty. The smell is, to my experience, always strong
and a reliable character, although interpreted somewhat
differently by different collectors. In my opinion it is
clearly disagreeable, reminiscent of raw potato.The yellow colours may
be visible as a shade on the pileus, especially at the margin,
but I have seen this feature only in few collections. In
my collections I have only seen yellow tinge at the edge
of the lamellae, and even then not in all specimens. The
stipe may show a violaceous hue at the apex, especially in young stages, although not very often. Another striking character is the wide hyphae of the pileipellis.
In Sect. Filipedes there are some
other species, also with yellow colours. M.
arcangeliana smell of iodoform
on drying out, and it is typically growing on decayed wood.
The lamellae often turn pinkish or flesh-coloured with
age. The smell of M. chlorantha
is indistinctive, turning to an odour of
iodoform when drying out. The pileus is usually more greenish
yellow, and this species is usuallu found in sand dunes.
The wide hyphae of the pileipellis is a character that it shares with M. rapiolens, which can be recognized by the somewhat darker gills that lack a yellow edge.
The habit of M. fagetorum and M. flavescens is similar but they differ markedly in micro-characters.
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