What is a Mycena?

© JJ Wuilbaut

Mycena includes a great number of species of which quite a few have very specific habitat demands. Many of them have beautiful colours and they show a great variation in microscopic structures. Being so small, however, (the pileus diameter rarely exceeding 5 cm) the Mycena species have not attracted too many mycologists. Although some of the most skilled mycologists have been working with the genus, which resulted in two large monographs (R. Kühner, 1938 and A. H. Smith, 1947), it was not until R. A. Maas Geesteranus started his revision of the genus in the 1980's, that a grewing interest could be observed among Europaen mycologists.

Many new species have been proposed the recent years, both by Maas Geesteranus as well as by other mycologists. Probably there are many left to be described. Maas Geesteranus published a conspectus with identfication keys and descriptions, which is an indispensable tool for identifying Mycenas today. However, many new species have been discovered after he had terminated his work. There is need for a new compilation. This site, however, will only deal with the North European species.

Generic characters

  • Habit mycenoid or omphaloid, more rarely collybioid
  • Pileus glabrous, granular, floccose, puberulous, or pruinose, sometimes covered with a gelatinous, sparable pellicle
  • Lamellae ascending, horizontal or arcuate, almost free or narrowly adnate to decurrent
  • Stipe fragile to cartilaginous or elastic-tough, in part or entirely pruinose or puberulous, or glabrous, sometimes dilated below to form a basal disc, often basally covered with long, coarse fibrils
  • Basidia 2- or 4-spored
  • Spores usually pip-shaped, less frequently almost cylindrical or spherical, generally amyloid, more rarely non-amyloid
  • Cheilocystidia clavate, obpyriform, fusiform, lageniform or, more rarely, cylindrical, smooth , branched or with variously shaped, simple or branched excrescences
  • Pleurocystidia numerous, scarce or absent
  • Hyphae of the pileipellis diverticulate, less frequently smooth
  • Hyphae of the cortical layer of the stipe smooth or diverticulate, sometimes with terminal cells or caulocystidia
  • Lamellar trama staining vinaceous to purplish brown in Melzer's reagent, in a few cases remaining unaltered

Go to Diagnostic characters


© Arne Aronsen 2002-2023