A Mushroom That Causes Vivid Hallucinations With No Known Psychedelic Compound

A wild mushroom eaten at hot pot restaurants in Yunnan, China has been sending people to the hospital with visions of tiny marching figures for generations. Now, a genomic study published in Mycologia has confirmed the unsettling truth: Lanmaoa asiatica lacks every biosynthetic gene researchers know to look for when hunting for a fungal hallucinogen. This is early-stage science, but the implication is striking: the mushroom may operate through chemistry that has never been characterized before.

Lilliputian hallucinations from Lanmaoa asiatica

More than a hundred cases of L. asiatica poisoning are treated annually at a single Yunnan hospital. The experience is consistent across patients: colorful figures a few centimeters tall appear, marching, dancing, and climbing, with effects that sharpen when the eyes are closed. Clinicians call these Lilliputian hallucinations, named after the tiny inhabitants of Jonathan Swift's fictional island. A November 2025 report by lead researcher Colin Domnauer found that 96% of hospitalized patients saw "little people". Similar accounts appear in the northern Philippines and in a third-century Chinese Daoist text, suggesting the mushroom's effects have been observed for centuries. Yunnanese restaurants now issue seasonal warnings and set timers at the table. As Domnauer himself noted after visiting one such restaurant: "The server set a timer for 15 minutes and warned us, 'Don't eat it until the timer goes off or you might see little people.'" The poisonings occur when the mushroom is eaten undercooked; fully cooked, it remains a prized edible.

Why an unknown psychedelic mechanism matters for fungal research

Science currently recognizes two well-described families of psychoactive fungi. The first operates via psilocybin, the compound that gives magic mushrooms their effects and that temporarily disrupts brain networks involved in introspective thinking. The second works through ibotenic acid and muscimol, the compounds in the Amanita muscaria fly agaric. L. asiatica belongs to neither family. Its genome contains none of the biosynthetic gene clusters associated with either pathway. Among fungi with unknown psychoactive mechanisms, L. asiatica stands out because the hallucinations it produces are so consistent and so well documented. If a third chemical pathway is confirmed, it could reshape understanding of how fungi evolved psychoactivity and potentially reveal new targets for neuroscience research.

How 53 genomes resolved the Lanmaoa phylogeny

The team, led by Colin Domnauer and Bryn Dentinger of the University of Utah and the Natural History Museum of Utah, sequenced whole genomes from 53 specimens across the genus Lanmaoa and built a phylogeny using 1,515 single-copy orthologous genes. DNA from 21 type specimens was included to reorganize species boundaries. That analysis resolved 17 recognized species within the genus, including two newly described: Lanmaoa fallax and Lanmaoa carbonilivor. The genus was first formally described in 2015 by Chinese mycologists Nian-Kai Zeng and Zhu L. Yang, and L. asiatica itself was formally named that same year. Phylogenomically, it sits closer to the common porcini than to any hallucinogenic species previously known, which makes its psychoactive effects all the more anomalous. The researchers also mined the L. asiatica genome for biosynthetic gene clusters tied to known fungal hallucinogens and found none. Chemical extracts of the mushroom produced comparable behavioral effects in mice, including hyperactivity followed by stupor, mirroring the human pattern. The study was funded by the National Science Foundation award DEB-2114785.

The bluing reaction visible when L. asiatica is bruised, the source of its local name 'jian shou qing' ('see-hand-blue'), is unrelated to psilocybin. Researchers attribute it to enzymatic oxidation of gyrocyanin, a compound with no known psychoactive properties.

What previous chemical analyses failed to find

The specific compound responsible for the Lilliputian hallucinations remains unidentified despite sustained effort. Previous chemical analyses of isolated compounds from the mushroom yielded no obvious culprit. Plasma metabolic profiles taken from patients experiencing poisoning in 2025 also failed to account for the visions. Detecting novel psychoactive substances is genuinely hard: non-targeted testing requires advanced data processing, and a compound could be active at concentrations that standard screens miss. The mechanism of action for the Lilliputian hallucinations specifically, which differ qualitatively from the visual effects of psilocybin or muscimol, is entirely uncharacterized. Earlier chemical work on known analytical methods for fungal hallucinogen detection focused on psilocin, ibotenic acid, and muscimol; none of those frameworks apply here.

Identifying Lanmaoa's active compound is the next step

The Domnauer and Dentinger team is actively working to isolate the active constituents. The genomic and phylogenetic groundwork they have now published gives future chemists a cleaner target: they can rule out entire biosynthetic families and focus resources on what the genome does contain. The genus Lanmaoa is globally distributed across Asia, the Americas, and Europe, which raises the question of whether related species share any psychoactive properties. If the compound is eventually isolated and characterized, it could open a genuinely new chapter in the pharmacology of fungal natural products. For now, the most honest summary is this: hundreds of people a year experience vivid, consistent hallucinations from a mushroom, and researchers do not yet know why.

Evidence rating

INVESTIGATIONAL — 69/100

Caveats:

• The active compound(s) responsible for the hallucinogenic effects remain unidentified; no causal mechanism has been established.
• Human clinical data are limited to observational case series from a single regional hospital; no controlled trials exist.
• Mouse behavioural data from crude chemical extracts cannot be directly extrapolated to human pharmacology.
• NSF-funded study (award DEB-2114785); no industry conflicts identified, but the research is at an early discovery stage with no replication in independent laboratories.

Phylogenomic study sequencing 53 fungal genomes and 1,515 orthologous genes from the bolete genus Lanmaoa. The study establishes a resolved species phylogeny and rules out known hallucinogen biosynthetic pathways by genome mining, but cannot identify the active compound or explain the mechanism of toxicity. Human data derive from an observational case series at a single hospital; mouse behavioural work used crude extracts. No independent replication of the genomic or toxicological findings has been published to date.

References

1. Colin Domnauer, Bryn T. M. Dentinger (2026). Phylogenomic systematics of Lanmaoa (Boletaceae) reveals cryptic diversity, resolves global evolutionary relationships, and suggests a novel psychoactive lineage. Mycologia. https://doi.org/10.1080/00275514.2026.2670968
2. Psilocybin generates psychedelic experience by disrupting brain network. medicine.wustl.edu. https://medicine.wustl.edu/news/psilocybin-generates-psychedelic-experience-by-disrupting-brain-network/
3. Krzysztof Ciszowski, Angelika Ziaja, Ewa Niedzielska-Andres, Lucyna Pomierny-Chamioło (2025). Natural hallucinogens of fungal and animal origin: action and potential applications — a narrative review. Folia Medica Cracoviensia. https://doi.org/10.24425/fmc.2025.156119
4. Challenges in Identifying Novel Psychoactive Substances and a Stronger Path Forward. nij.ojp.gov. https://nij.ojp.gov/topics/articles/challenges-identifying-novel-psychoactive-substances-and-stronger-path-forward
5. Katarzyna Stebelska (2013). Fungal Hallucinogens Psilocin, Ibotenic Acid, and Muscimol. Therapeutic Drug Monitoring. https://doi.org/10.1097/ftd.0b013e31828741a5