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Psilocybe samuiensis

Common name: Ko Samui Psilocybe

Field Identification

Cap0.5-2cm; convex to campanulate; chestnut to cinnamon-brown; hygrophanous; slight umbo
GillsAdnate; initially cream-gray, darkening to dark purple-brown; close
Stem3-6cm; whitish to pale; bruises blue when handled; fragile
Spore PrintDark purple-brown; ellipsoid, 9-12 x 5.5-7 um
HabitatBuffalo and cow dung, rice paddies, pastures, grassy roadsides in tropical lowlands
DistributionThailand (Ko Samui, Ko Pha Ngan, Kanchanaburi), Vietnam, Southeast Asia
SeasonYear-round in tropical climate; peak during rainy season

Key Identification Feature

Dung and rich soil habitat in Thai lowlands. Small size. Dense clustering. Blue bruising throughout. Found on Ko Samui and Ko Pha Ngan — islands famous for psychedelic mushroom tourism.

⚠ Dangerous Lookalikes

Psilocybe cubensis (same habitat, much larger cap; far more commonly used); Panaeolus cyanescens (also on dung, Thai islands, black spore print)

Notes

The Thai island of Ko Samui and neighboring Ko Pha Ngan became internationally known for their Full Moon parties and psychedelic mushroom shakes served openly at beach bars in the 1990s and early 2000s. P. samuiensis was among the species involved, often alongside P. cubensis. Thailand reclassified psilocybin mushrooms as controlled substances in 2022.

Legal Status Warning Psilocybin-containing mushrooms are controlled substances in most jurisdictions. This guide is for educational purposes only. Wild foraging for psilocybin mushrooms may be illegal in your location. Never consume wild mushrooms without positive identification from an expert mycologist — misidentification can be fatal.

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