The taxonomy and biology of Mycena citricolor (Berk and Curt.) Sacc. is reviewed and techniques of induction of basidiocarps by certain other fungi are described.

Mycena citricolor was induced to produce the perfect stage when grown in co-culture with Penicillium oxalicum, P. palitans, P. cyclopium, P. brevi-compactum, or P. viridicatum. Basidiocarp yield was highest when M. citricolor was grown in co-culture with P. oxalicum. A low percentage of field isolates of M. citricolor were able to produce some basidiocarps in mono-culture, but yield was greatly increased when this fungus was grown in co-culture with P. oxalicum. Other isolates of M. citricolor produced basidiocarps only when grown in co-culture with P. oxalicum. However, several other basidiomycetes failed to produce the perfect stage when grow in co-culture with P. oxalicum.

A basidiocarp-stimulating substance(s) (BSS) was present in sterile supernatant fluids from cultures of Penicillium oxalicum. BSS resisted autoclaving and readily passed through dialysis tubing. Yield of BSS was highest when P. oxalicum was cultured in potato dextrose broth (PDB) or Emerson’s YpSs medium in still culture for 1 week under laboratory conditions. P. oxalicum grown in PDB produced BSS independently of light conditions, but M. citricolor produced basidiocarps in response to BSS (or in co-culture with P. oxalicum) only when grown in alternating periods of light and dark. M. citricolor produced basidiocarps only when it was cultured on natural or semi-synthetic media.