A cup fungus whose asexual stage (Chromelosporium) is known as peat mould and, on mushroom farms, as cinnamon or brown mould (Hennebert & Korf 1975; Stamets & Chilton 1983). It typically grows on steam-sterilised greenhouse soil and other substrates that have been heated (Pfister et al. 2024). On button-mushroom (Agaricus) farms it forms white patches on compost or casing that turn golden to cinnamon brown as they sporulate. It indicates overheating or poor heat management rather than being a serious competitor, although severe outbreaks can reduce yields (Gajanayake et al. 2025; Stamets & Chilton 1983).
Not edible; a contaminant of mushroom beds. Stamets & Chilton (1983) considered the brown or cinnamon mould apparently harmless, with no known toxic species. No other health data were found. The genus record warns that Peziza edibility is largely unknown and that some species are poisonous.
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Mycology is an evolving science: names, classifications and safety information change as research advances. Entries are compiled from cited sources and reviewed, but may be incomplete or out of date — check the sources, and never rely on this library alone to identify or eat a mushroom.
Habitat
Greenhouse soil after steam sterilisation and other heat-exposed substrates (Pfister et al. 2024). On mushroom farms: casing soil, especially woody mixes, damp woodwork, and less often compost (Stamets & Chilton 1983; Gajanayake et al. 2025). Soil, casing mixes and damp wood are the main sources of inoculum (Gajanayake et al. 2025).
Distribution
Cinnamon mould is reported on Agaricus farms in India, South Africa and the USA (Gajanayake et al. 2025, as Chromelosporium fulvum). The species is listed in the UK species inventory (NBN Atlas). Its full range was not verified.
Characteristics
Asexual stage on beds: circular patches of white aerial mycelium on compost or casing that turn light yellow or pale golden brown over a few days, then golden brown or cinnamon, and become granular. Fleshy cup-shaped fruit bodies (the sexual stage) may form on beds (Gajanayake et al. 2025). Stamets & Chilton (1983) describe it as white and grey at first, turning dull golden to cinnamon brown as spores mature. Sexual stage: ascospores finely reticulate and remaining hyaline, unlike the pigmented ascospores of the similar P. atrovinosa (Pfister et al. 2024).
