A fungus is an organism in the kingdom Fungi, alongside yeasts, molds and mushroom-forming species. GBIF’s classification places Psilocybe in kingdom Fungi, phylum Basidiomycota, order Agaricales (GBIF). Fungi are not plants: they feed on organic matter rather than making food from light, which is why their names follow special rules in the same code as plants.
“Mushroom” and “fungus” are not the same thing. Most of a fungus is mycelium, a hidden network of threads; the mushroom is its fruiting body, built to release spores. Fungi can also form other structures, such as sclerotia or underground truffles (Kennedy et al., 2026).
The difference matters for psilocybin. Almost all known producers are mushroom-forming fungi, but psilocybin has also been found in cicadas infected by Massospora, an insect-killing fungus that makes no mushroom (Boyce et al., 2019). In everyday speech “magic mushrooms” means the mushroom-forming species; scientifically the organism is the whole fungus.
Sources
- GBIF species record: Psilocybe classification
- Kennedy et al., 2026, Mycorrhiza
- Boyce et al., 2019, Fungal Ecology
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