A professor in Yunnan ate stir-fried mushrooms, lifted the tablecloth, and saw hundreds of tiny people marching underneath it like soldiers. When he raised the cloth higher, he reported, their heads came off and stuck to the fabric while the bodies kept marching in place. He measured them. They were two centimeters tall.
That account is neither folklore nor an outlier. According to records from a Yunnan hospital, 96% of patients affected by one particular mushroom describe seeing an abundance of little people or elves, often dancing, jumping, or marching through the real room around them.
Genomic work published in the journal Mycologia and highlighted by the University of Utah this month has now pinned the phenomenon to a single species, deepening the mystery rather than solving it.
The Same Visions Turned Up in Two Unconnected Countries
Doctoral student Colin Domnauer and mycologist Bryn Dentinger, of the University of Utah and the Natural History Museum of Utah, sequenced whole genomes from 53 mushroom specimens across the genus Lanmaoa, including 21 type specimens.
The species behind the Yunnan reports is Lanmaoa asiatica, known locally as jian shou qing, which roughly translates to "turns blue in the hand" because its flesh discolors within seconds of being cut. It is a bolete, more closely related to porcini than to any known hallucinogenic mushroom, and it is a prized edible sold openly in markets. Undercooking is what causes trouble.
Domnauer traveled to the northern Philippines in 2024 to investigate an independent report of identical visions, tied to a mushroom local communities call Sedesdem. It turned out to be the same species, which was itself a surprise since L. asiatica had been thought to occur only in China.
The clinical term for the effect is Lilliputian hallucination, after the six-inch inhabitants of Gulliver's Travels. French psychiatrist Raoul Leroy coined the term in 1909, partly based on personal experience. A systematic review of 226 case descriptions found that the figures are perceived as grounded in the real environment in 97% of cases, which is what makes them so unlike a classical psychedelic experience.
The Genome Ruled Out Every Known Culprit
The team mined the L. asiatica genome for the biosynthetic gene clusters that produce psilocybin in Psilocybe mushrooms and ibotenic acid in Amanita muscaria. Neither was present. As the authors state in the published paper, genome mining failed to detect the canonical genes associated with either compound, suggesting a novel psychoactive substance.
Building a phylogeny from 1,515 single-copy orthologs, the researchers resolved 17 species in the genus, uncovered four new ones, and formally described two of them, Lanmaoa fallax and Lanmaoa carbonilivor. Their analysis indicated that L. asiatica is the only psychoactive species in the group.
The absence of known compounds is not a new suspicion. Western scientists first heard reports of mushroom-induced visions of tiny humans from Papua New Guinea in 1934, calling the phenomenon "mushroom madness." Expeditions in the 1950s and 1960s narrowed the culprit to boletes and ran chemical analyses that found nothing. Samples were even sent to Albert Hofmann, who first isolated psilocybin and discovered LSD. He could not identify an active compound either.
In plain terms: something in this mushroom produces one of the most specific hallucinations in medicine through a pathway nobody has described.
Why Neuroscientists Care About a Mushroom
Lilliputian hallucinations are not exclusive to fungi. Domnauer has noted that they also occur in alcohol withdrawal, in dementia, in macular degeneration, and in other neurological conditions.
But in those settings, they are rare and unpredictable. Nobody can produce them on demand, making them nearly impossible to study. This mushroom appears to generate them reliably, which is exactly what a research tool requires.
If the compound can be isolated, it would give researchers a way to probe how the brain assembles a perceived scene, specifically how internally generated imagery gets stitched into the incoming stream from the eyes and placed convincingly in real space.
The hunt is ongoing on two fronts. In Domnauer's account of the fieldwork, he reports that mice given chemical extracts of the mushroom shift their behavior compared with controls, and that the team is fractionating those extracts to narrow down the active molecule. Separately, a plasma metabolomics analysis of 20 poisoned patients identified 914 differential metabolites and flagged candidates, but did not identify the responsible compound.
This Is a Poisoning, Not a Recreational Drug
It is worth being blunt about the framing, because the story travels well and the details get lost.
People who experience these visions are hospitalized. A review of 81 patients admitted to one Yunnan emergency department over a year found that visual hallucination was the most common first symptom, in 69% of cases, followed by nausea and vomiting. Neuropsychiatric symptoms typically started 12 to 24 hours after the meal, well after the stomach trouble. Median hospital stay was three days. No patients died.
The mushroom is not sold or available in the United States, and there is no commercial or legal supply anywhere. Identification is genuinely difficult: when the Utah team DNA-sequenced the contents of online packages sold as dried jian shou qing, they found multiple poisonous species and no trace of the species on the label.
Anyone who develops confusion, hallucinations, or persistent vomiting after eating wild mushrooms should seek emergency care and bring a sample of what was eaten. Nothing about this research suggests a safe dose, because no dose has been characterized and no compound has been identified.
Key Questions Answered
What are Lilliputian hallucinations?
A clinically defined syndrome in which a person sees numerous miniature human, animal, or fantastical figures that appear to occupy the real space around them.
Which mushroom causes them?
Lanmaoa asiatica, a bolete sold as food in Yunnan, China, and found in the northern Philippines. DNA sequencing confirmed that the two regions were reporting the same species.
Does it contain psilocybin?
No. Genome mining found no genes for producing psilocybin or ibotenic acid, and chemical analyses dating back decades found no known hallucinogen.
Is it dangerous?
Cases present as mushroom poisoning and require hospital care. Reported effects include hallucinations, nausea, vomiting, and weakness. In one hospital series, no patients died.
Can people get it in the United States?
No. The species is not commercially available outside its native range, and no isolated compound exists.
Why does this interest neuroscientists?
Because the same hallucination occurs rarely and unpredictably in dementia, alcohol withdrawal, and eye disease. A reliable trigger would give researchers a way to study how the brain builds a perceived scene.
