Psilocybe samuiensis is a relatively popular recreational mushroom given its rarity and restricted range. It is rarely found outside of Thailand, occasionally near Angkor Wat in Cambodia. More specifically, the species is most commonly found in the Thai province of Ranong, on the island of Koh Samui from where it gained its name. After years of contentious debate on its identity, P. samuiensis became the first of the Mexicanae group of Psilocybe species to be found outside of the New World.
The confusion regarding its identification arose from the many similarities it shares with other members of the Psilocybe genus. Originally mistaken for P. mexicana or P. semilanceata, these options were eventually discounted, as neither is known to grow in Southeast Asia. P. cubensis is known to grow in Thailand, also a popular and similar recreational mushroom in the area, but grows readily on dung, unlike P. samuiensis.
Either introduced by tourists in the 60s and 70s, or arising naturally among the local populations, recreational use of magic mushrooms has become commonplace among certain resorts and towns on the islands of the Chumphon archipelago in the Gulf of Thailand. The preferred vehicle for their use is the “mushroom shake”, a smoothie or milkshake that helps to mask the bitterness of the psychoactive mushrooms mixed in. In some restaurants, it may not be uncommon to have different fungi mixed into regular menu items.
This tourism-driven demand for mushrooms has spurred farming by the local populations. The farmers, and especially their children, have developed extensive knowledge of regional mycology and have become the go-to experts for visiting scientists. A catch-all term of “hed keequai” (translated to “the divine mushroom that grows from dung”) that originally referred to P. cubensis has extended to include any magic mushroom found in the region.
While the children usually hunt for the larger P. cubensis, they are reliably able to identify the very similar P. samuiensis, a task that has challenged trained experts in the past. Their wild cultivation is further complicated by the variety of other mushrooms found in the same habitat: P. samuiensis, P. cubensis and P. cyanescens have been found growing within meters of each other in the same farmer’s field.
P. samuiensis does maintain some characteristics that assist in their identification. They are frequently found with a small papilla or umbo, similar to the “liberty cap” P. semilanceata. They have a separable, gelatinous pellicle that makes the cap sticky to the touch when wet. Their short stipe is thin and covered in whitish fibrils or hairs, bruising blue readily near the base.
The preferred ecology for P. samuiensis is the sandy, clay-rich soils of meadows and rice paddies. It is found fruiting in late summer alongside other Psilocybe species, making them relatively rare compared to the others. Their small size may contribute to this perception, as their are frequently overlooked for bigger or more potent species.
Though small, this species is considered to have a moderate to high potency. It contains psilocybin, high levels of psilocin and trace amounts of baeocystin. At a maximum size of only 5-7.5 centimeters, fifteen to twenty fresh mushrooms can induce an “intensely visual experience” as described by the mycologist Jochen Gartz. Their flavour is considered mild, floury and lightly herbal.
P. samuiensis is capable of growing artificially, though it is not very common due to its difficulty. Online retailers may sell spores or grow-kits of ambiguously labelled “Thai” strains; many of these are mislabelled and actually the more common species P. cubensis. While the species does not fruit quickly or readily, the initial mycelium growth is fast, on par with P. tampanensis. However, while the latter species then quickly produces large “truffles”, P. samuiensis may only produce very small sclerotia after three months of vigilant care.
The mycelium produced by P. samuiensis does not undergo a bluing reaction when damaged or aged. While this would normally indicate non-existent or low potency, significant levels of psilocybin and psilocin are found regardless. Grown on an appropriate medium, this may allow for the direct harvest of mycelium without waiting for fruiting to occur. Many published accounts of their artificial cultivation describe prompt growth in malt-agar and grass seed media.
Though not impossible indoors, fruiting of P. samuiensis requires care and diligence. For those finding success, specific mixtures of grains and other additives were used. Only after three to four months of patience did the small mushrooms begin to appear. Thankfully, those grown in the laboratory match those from the wild in regards to potency and levels of active compounds.
P. samuiensis can provide a memorable experience if found on a vacation to Thailand, or in their dried form from a reputable location. In all these cases, the products are usually mislabelled samples of P. cubensis, but with effort one may be able to find and enjoy this elusive Thai species.