Abstract
Many conditions affect the production of mature apothecia of Ciboria acerina in culture. In this investigation four factors were studied: age of isolate, temperature at which the cultures were grown, host from which the cultures were isolated, and the absence or presence of light. It was found that no apothecia were produced when the isolate was more than 18 months old. The temperature at which the stroma of C. acerina developed was significant in apothecium production. Stroma grown at 14 °C produced apothecia while stroma grown at 5 °C did not. However, apothecia matured over a temperature range of 5–22 °C. Apothecia were produced in cultures isolated from Acer, Alnus, and Populus. The quality of light received did not affect apothecium production. The absence of light at all stages of the growth of this fungus from the time of inoculation to the appearance of mature fruit bodies was not a limiting factor. Mature apothecia of Ciboria acerina were formed under artificial conditions in darkness.