In small groups to densely cespitose on
decaying wood and stumps of conifers (Picea, Pinus). Late summer to autumn. The species is mainly hemiboreal-boreal-subalpine and would appear to be present in parts of the area covered. It is not known from Denmark nor the UK. In Norway occasional and locally common.
mm across, parabolical to convex, sometimes umbonate, and
often somewhat depressed centrally, glabrous, sometimes
conspicuously sulcate, sometimes not or very shallowly sulcate,
translucent-striate, somewhat lubricous when wet, hygrophanous, white to cream, often
with a tinge of pale brownish pink at the centre, occasionally stained with rownish spots with age. Lamellae
23-28 reaching the stipe, ascending, (broadly) adnate,
decurrent with a tooth, white, with age sometimes slightly
tinged with pink. Stipe 30-70
x 1-3 mm, hollow, straight to curved, equal, terete, glabrous,
lubricous when wet, tough, white, darker to grey towards
the base especially in younger specimens, the base often
rooting, covered with whitish fibrils. Odour
not distinct. Taste mild to slightly farinaceous.
Basidia 20-30 x
6-7.5 µm, slenderly clavate, 4-spored, with sterigmata 3-5 µm long. Spores
7-9 x 3.8-4.8 µm, Q 1.8-2.1, Qav ≈ 1.9, pip-shaped, smooth, amyloid. Cheilocystidia
25-40 x 5-9 x 1-3 µm, more or less forming a sterile
band, fusiform to sublageniform, smooth, apically
narrowed into a generally acute, at times more rounded,
simple to furcate neck. Pleurocystidia not seen. Hyphae
of the pileipellis 1.5-4.5 µm
wide, smooth, embedded in gelatinous matter. Hyphae
of the cortical layer of the stipe 1.5-3
µm wide, more or less embedded in gelatinous matter,
smooth to sparsely diverticulate with excrescences 1.5-7 x 1-2 µm, terminal cells diverticulate. Clamp connections present in all tissues.
Mycena laevigata is usually easily
identified on account of the white colour and occurence
on conifer wood. The microscopic features identify it as
a member of sect. Fragilipedes,
in which it can be separated by the smooth hyphae of the
pileipellis, embedded in gelatinous matter, and the diverticulate
hyphae of the cortical layer of the stipe. The cheilocystidia
with the usually long, acute neck is also a reliable character.
According to Maas Geesteranus (1988 a) the number of lamellae
reaching the stipe is 15-23, a smaller number than I have
recorded. It should be noted that probably all Mycena species can occur in white forms, and this can cause problems. M. laevigata is not entirely white. First of all, the stipe usually is grey towards the base, and the gills are often slightly tinged pink.
Maas Geesteranus (1988) described
the new species Mycena laevigatoides from Germany,
which can be separated from M. laevigata on account
of diverticulate hyphae of the pileipellis, not embedded
in gelatinous matter, and association with deciduous trees.
Mycena lignivora Maas Geest.
was described from Switzerland (Maas Geesteranus 1995). The author
mentioned a possible confusion with M. laevigata
because of the pink colour of the lamellae, but stated that
the two species could be told apart on account of the colour
of the pileus (pale dingy pinkish brown in M. lignivora)
and the hyphae of the stipe cortex (smooth in M. lignivora).