Taxonomy
- Kingdom: Fungi
- Division: Basidiomycota
- Class: Agaricomycetes
- Order: Agaricales
- Family: Bolbitiaceae
- Genus: Panaeolus
- Species: Panaeolus olivaceus (Berk.) Sacc., 1885
Common Names
- Olive Panaeolus
- Olive dung mushroom
Morphological Description
- Cap: 1–3 cm in diameter; convex to broadly convex, often flattening with age; surface smooth, moist, ranging from olive‑brown to gray‑olive; sometimes exhibits a faint translucent pellicle.
- Gills: Crowded, adnexed to free; dark brown to blackish at maturity due to spore deposition.
- Spore Print: Dark brown to black.
- Stipe: 3–7 cm long, 2–4 mm thick; cylindrical, hollow, matching or slightly lighter than the cap; surface smooth, lacking a ring.
- Microscopic Features: Spores ellipsoid, smooth, measuring approximately 12–14 µm × 8–10 µm; basidia typically four‑spored.
Ecology and Habitat
- Ecological Type: Saprotrophic, coprophilous (grows on animal dung).
- Typical Substrate: Fresh to moderately aged dung of herbivores such as cows, horses, and sheep; occasionally found on rich, grassy soils enriched with dung.
- Fruit‑body Season: Late summer to autumn in temperate regions; can appear after periods of rain.
Geographic Distribution
- Reported from a wide range of temperate zones, including Europe (e.g., United Kingdom, Germany, Sweden), North America (e.g., United States, Canada), and parts of Asia. Distribution records are based on herbarium specimens and field surveys.
Chemical Composition and Psychoactivity
- Some mycological studies and field reports list Panaeolus olivaceus as containing psilocybin and psilocin, the hallucinogenic indole alkaloids found in several Panaeolus species.
- Quantitative analyses are limited; the reported concentrations are generally low compared to more potent species such as Panaeolus cyanescens or Psilocybe spp.
- Because of the scarcity of rigorous chemical data, the psychoactive status of P. olivaceus remains uncertain and is considered insufficiently documented in the scientific literature.
Edibility
- The species is not regarded as edible. Owing to the potential presence of psychoactive compounds and the lack of comprehensive toxicity studies, it is generally classified as “not recommended for consumption.”
Similar Species
- Panaeolus semiovatus – larger caps, typically more whitish and less olive‑colored.
- Panaeolus foenisecii – grows on grass rather than dung and has a lighter, often brownish cap.
Conservation Status
- Not evaluated by the IUCN Red List. The species is considered common in suitable habitats and does not currently face known conservation threats.
References (selected)
- Arora, D. (1986). Mushrooms Demystified. Ten Speed Press. – Provides macroscopic description and habitat information.
- Guzmán, G., & Guzmán-Dávalos, L. (1998). “The genus Panaeolus (Basidiomycetes) in Mexico.” Mycotaxon, 64, 177‑190. – Discusses taxonomy and psychoactive compounds within Panaeolus.
- Stamets, P. (1996). Psilocybin Mushrooms of the World. Ten Speed Press. – Mentions P. olivaceus among reported psilocybin‑containing species, noting limited analytical data.
Note: While multiple reputable sources acknowledge the possibility of psilocybin presence in Panaeolus olivaceus, the lack of extensive quantitative studies means that definitive statements about potency or safety cannot be made.
