Gregarious on fallen coniferous needles. Autumn. Widespread in the area covered and mostly common but less frequent in lowlands of western parts. Widely distributed and very common in southern parts of Norway. Often occuring in great numbers. Recorded north to Nordland County.

Pileus 5-20 mm across, conical to parabolical or convex, occasionally with a pointed umbo or somewhat depressed in the centre, flattening with age, sulcate, translucent-striate, lubricous to viscid, glabrous, covered with a separable, gelatinous pellicle, dark brown at the centre, paler brown to greyish brown towards the margin. Lamellae 14-25 reaching the stipe, arcuate, broadly adnate to decurrent, veined and dorsally intervenose with age, pale grey to pale grey-brown; the edge separable as an elastic-tough thread, paler or concolorous. Stipe 20-60 x 1-1.5 mm, hollow, equal or somewhat wider at the apex, straight to flexuous, pruinose above, glabrous for the greater part, glutinous to viscid, covered with a separable, gelatinous pellicle, whitish at the apex, grey-brown to fairly dark brown farther below, the base covered with long, coarse, whitish fibrils. Odour none or somewhat fruity farinaceous. Taste reported as raphanoid.

Basidia 22-33 x 6-9.5 µm, clavate, 4-spored, with sterigmata 4.5-5.5 µm long. Spores 7-9(-11) x 3.5-4.5(-5) µm, Q 1.8-2.2, Qav ≈ 2, pip-shaped, smooth, amyloid. Cheilocystidia 18-35 x 2-4.5 µm, forming a sterile band, cylindrical, embedded in gelatinous matter, terminated by much branched, gelatinizing excrescences2-13 x 1-2.5 µm. Pleurocystidia absent. Lamellar trama dextrinoid. Hyphae of the pileipellis 2.5-3.5 µm wide, smooth or somewhat diverticulate with cystidia-like terminal cells with much branched excrescences, embedded in gelatinous matter. Hyphae of the cortical layer of the stipe 1.5-3.5 µm wide, smooth, tortuous, embedded in gelatinous matter, terminal cells densely diverticulate. Clamp connections present in all tissues.

Mycena vulgaris is a species of section Fuliginellae, of which only seven species are known, four in North America and three in Europe. Four species have, like M. vulgaris, arcuate lamellae. M. austinii (Peck) Kühner can be distinguished on account of of its white pileus, presence of a basal disc, clavate cheilocystidia and presence of pleurocystidia. M. mackinawensis A. H. Sm. is different because of clavate cheilocystidia, presence of pleurocystidia, differently shaped terminal cells of the hyphae of the pileipellis, and occurrence on coniferous branches. M. agrestis differs in having somewhat larger spores, differently shaped cheilocystidia, and no association with conifers. M. geesterani Heykoop, Esteve-Rav. & G. Moreno, recently described from Spain, is supposed to have smaller spores (4-5 x 2-2.5 µm) that are more strongly amyloid. It was also described with white lamellae with ochre-yellowish to reddish shades.

A quite aberrant collection of Mycena vulgaris was found by this author in 2003. It deviated from normal M. vulgaris by a black apex of the stipe and blackish to dark grey pileus. The microscopic details, however, did not differ from typical M. vulgaris.

Because of the viscid appearance of the pileus and stipe M. vulgaris could be taken for a member of sect. Hygrocyboideae. M. vulgaris, however, never shows any yellow colours which are so conspicuous in most varieties of Mycena epipterygia, and in the latter the lamellae are ascending and adnate (although decurrent with a tooth), never arcuate. The two varieties of M. epipterygia lacking yellow shades, var. fuscopurpurea and var. pelliculosa do not grow on coniferous needles. The spores of M. epipterygia are larger, and the hyphae of the pileipellis are branched, anastomosing, often forming dense masses.

Another species with a lubricous pileus (at least in moist conditions) and a glutinous stipe together with somewhat decurrent lamellae is Mycena clavicularis. It has, however, not a separable pellicle nor a separable lamellar edge, and the microscopy is completely different.