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.

Pileus 10-30 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).