On fallen and often buried cones of Picea in moist spruce forest. Widespread in the region but apparently absent in many lowland areas, including Denmark and the Netherlands. In Norway widely distributed in the Picea area up to Trøndelag. Occuring in the spring.

Pileus 8-38 mm across, parabolical, campanulate to conical, often flattening with age with broad umbo, sometimes also somewhat umbilicate, smooth, hygrophanous, not sulcate, hardly translucent-striate, glabrous, slightly lubricous, dark chestnut to sepia brown, paler towards the margin. Lamellae 20-40 reaching the stipe, ascending, ventricose, narrowly adnate to adnate, dorsally intervenose in older specimens, whitish to pale grey, sometimes turning pink with age. Stipe 30-70 x 1.5-3.5 mm, straight to curved, hollow, terete, equal, somewhat firm, glabrous except for the minutely pruinose apex, grey brown, whitish above and dark brown towards the base, which is covered with coarse, long, whitish fibrils. Odour nitrous.

Basidia 22-30 x 7-8 µm, clavate, 4-spored. Spores 7-9.6 x 3.6-5.8 µm, Q 1.4-1.8, Qav~1.7, pip-shaped to phaseoliform, smooth, amyloid. Cheilocystidia 27-80 x 9-20 x 0-5.5 µm, forming a sterile band, lageniform, fusiform, subcylindrical, more rarely clavate, apically narrowed into a longer or shorter neck, or rostrate to mucronate, more rarely without a neck. Pleurocystidia similar. Hyphae of the pileipellis 1.5-3.5 µm wide, embedded in gelatinous matter, smooth or very occasionally with an isolated, cylindrical excrescence. Hyphae of the cortical layer of the stipe 2-3 µm wide, sligthly gelatinized, smooth, with cylindrical to fusiform caulocystidia up to 100 µm long. Clamp connections absent or very rare.

Almost all the Norwegian collections are from April and May. In this period of the year there are not many Mycena species fruiting, and considering the brown colour, the nitrous odour, and the growth on fallen Picea cones, this species should be easy to identify. In addition the smooth hyphae of the pileipellis and stipitipellis, the caulocystidia, the shape of the spores, and the absence of clamp connections are distinguishing characters. Mycena silvae-nigrae is another vernal, nitrous-smelling species with a brown pileus. It is also associated with Picea, and it has even been found growing on buried Picea cones (although very rarely). M. silvae-nigrae can be separated on account of 2-spored basidia, diverticulate hyphae of pileipellis and cortical layer of the stipe, and differently shaped cheilocystidia, usually with coarse excrescences.

Maas Geesteranus (1988: 289) claimed that M. strobilicola was devoid of clamps, and that is the general situation. Robich (2003: 319), however, stated that clamps were present, although very rare, in his material, observed only in the hyphae of the cortical layer of the stipe. Moreau (2003: 7) claimed that clamps are present but rare at the base of the basidia and at the hyphae of the trama in pileus and stipe. I have observed very rare clamps in the hyphae of the cortical layer of the stipe.

Moreau (2003) showed that Agaricus plumipes Kalchbr. is an anteriour and prioritary synonym of M. strobilicola and proposed the new combination Mycena plumipes (Kalchbr.) P.-A. Moreau.

Microscopic drawings