The effect of light on fruitbody initiation in Psilocybe cubensis

The effect of light upon fruitbody initiation in Psilocybe cubensis (Earle) Sing. was studied. Initiation only occurred when cultures were illuminated. Photoinitiation could be inhibited by poor aeration of the cultures or the lack of vegetative maturity. Only low levels of light were necessary for initiation (23 ergs/ sec/cm²/day for five days). Wavelengths of 370, 440, and 460nm were the most effective in the induction of fruitbody initiation. Wavelengths greater than S0Onm were ineffective. Certain abnormal forms are described which may be related to the build-up of gaseous products. The possible relationship between photo-initiation in fungi and phototropism in green plants is discussed.