Psilocybin Species & Mycology
1.78% psilocybin — reported, not re-measured
Psilocybe azurescens is widely called the most potent psilocybin mushroom on record. The number behind that claim comes from the species' original 1995 description and has never been independently reproduced in the largest modern survey of the genus — which did not sample azurescens at all.
Figure cited in Gotvaldová et al., Int J Mol Sci, 2022; originates with Stamets & Gartz 1995
15.543 mg/g
The highest psilocybin concentration anyone actually measured in a 226-fruiting-body survey was in Psilocybe serbica var. bohemica — 87% of the azurescens benchmark it was compared against (Gotvaldová 2022)
5 of ~165
Bradshaw 2024 (PNAS) phylogenomics: the psilocybin biosynthetic gene cluster is characterised in only five of roughly 165 Psilocybe species — not confirmed across the genus
94 specimens
Bradshaw 2022 re-examined 94 fungarium Psilocybe specimens across 18 species by DNA barcoding and found determinations 'largely unreliable, even at the genus level'
Figure cited in Gotvaldová et al., Int J Mol Sci, 2022; originates with Stamets & Gartz 1995
View as image ↗Psilocybe azurescens holds a reputation as the most potent psilocybin-producing mushroom ever documented. The figure attached to that reputation — 1.78% psilocybin by dry weight — is repeated across field guides, forums, and supplement copy as though it were a settled analytical result.
It is not. The number is real, but it originates in the paper that first described the species in 1995, and it has not been independently re-measured since. The largest systematic tryptamine survey of psychotropic mushrooms yet published — 226 fruiting bodies across 82 collections and seven genera, quantified by UHPLC–MS/MS — did not include a single azurescens specimen.[1]
That gap does not make azurescens weak. It makes the specific claim more fragile than the confidence with which it travels. This article covers where the potency figures actually come from, what the largest modern dataset does and does not support, what the baeocystin content really means pharmacologically, where the species grows, and the identification problem that undercuts every potency claim attached to a field specimen. The guide to Psilocybe cubensis covers the comparative baseline for the most widely studied species.
Key Takeaways
- The 1.78% psilocybin figure (17.8 mg/g) traces to the original species description by Stamets and Gartz in 1995, not to modern LC–MS analysis — Gotvaldová 2022 cites it as a benchmark but did not sample azurescens
- The companion figures usually quoted alongside it — 0.38% psilocin and 0.35% baeocystin — appear nowhere in Gotvaldová 2022 in any context, and have no accessible peer-reviewed re-measurement
- The highest psilocybin concentration actually measured in that 226-fruiting-body survey was 15.543 mg/g in Psilocybe serbica var. bohemica — within 15% of the azurescens benchmark, which the authors explicitly noted as comparable
- Against measured cubensis (0.651–3.509 mg/g in the same study), the azurescens benchmark is roughly 5× — so "4 to 5 times cubensis" holds, but "in a class of its own" does not
- Both preclinical papers cited for baeocystin's significance found it did not produce head twitch responses, the standard rodent marker of psychedelic activity; Rakoczy 2024 concluded these minor tryptamines may have therapeutic potential "without causing hallucinations"
- Bradshaw 2022 re-examined 94 fungarium specimens across 18 species and found determinations largely unreliable even at genus level — so potency figures apply only to DNA-verified material
- Bradshaw 2024 (PNAS) placed azurescens in the lignicolous clade with P. cyanescens, but characterised the psilocybin gene cluster in only five of ~165 Psilocybe species
Where the Potency Numbers Actually Come From
The potency figures for P. azurescens trace back to the species' original formal description: Stamets and Gartz, "A new caerulescent Psilocybe from the Pacific Coast of Northwestern America," published in Integration in 1995. That journal is not indexed in PubMed, and the paper is not readily accessible.
The figure is nonetheless documented in the peer-reviewed literature — as a citation. Gotvaldová and colleagues' 2022 survey mentions azurescens exactly once, in a single sentence of discussion, and the context is worth quoting precisely: their highest measured value, 15.543 mg/g psilocybin in P. serbica var. bohemica, "was the highest determined in the whole dataset and P. serbica var. bohemica is therefore comparable with the highly potent P. azurescens with PSB concentrations reported of up to 17.8 mg/g PSB."[1]
Seventeen point eight milligrams per gram is 1.78% by dry weight. That is the entire basis for the number, inside the largest survey of the genus: a bracketed reference to prior literature, used as a yardstick for a value the authors did measure.
Citation Chain Audit
Following “1.78% Psilocybin” Back to Its Source
This is the number that makes P. azurescens famous, and it is routinely presented as a modern laboratory measurement. Each step below is a link in the chain; the highlighted steps are where it breaks.
The claim as it circulates
Psilocybe azurescens contains up to 1.78% psilocybin by dry weight — plus 0.38% psilocin and 0.35% baeocystin — making it the most potent psilocybin mushroom on record.
The source it is usually attributed to
Gotvaldová et al., International Journal of Molecular Sciences 23(22):14068 (2022). PMID 36430546. The largest systematic tryptamine survey of psychotropic mushrooms published to date.
What that paper actually sampled
226 fruiting bodies from 82 collections across seven genera, quantified by UHPLC-MS/MS, most vouchered by fungarium specimens and/or ITS rDNA sequencing. Psilocybe azurescens is not among the species analysed. It is not in Table 1. No azurescens specimen was measured.
The single sentence in which it appears
"…P. serbica var. bohemica is therefore comparable with the highly potent P. azurescens with PSB concentrations reported of up to 17.8 mg/g PSB [58]." That is the entire mention. 17.8 mg/g is 1.78% — and it enters the paper as a bracketed citation to earlier literature, used as a yardstick for the authors’ own highest measured value.
Where the number actually comes from
The original formal description of the species: Stamets & Gartz, "A new caerulescent Psilocybe from the Pacific Coast of Northwestern America," Integration 6:21–28 (1995). It is not indexed in PubMed. The 0.38% psilocin and 0.35% baeocystin figures appear nowhere in Gotvaldová 2022 in any context.
What this does not mean: it does not mean P. azurescens is weak, or that the 1.78% figure is invented. It means the figure rests on the original 1995 species description rather than on modern LC–MS re-measurement, that it has not been independently reproduced in the largest survey of the genus, and that a claim of this specificity is carrying more analytical weight than its source can bear. A species can be genuinely potent and still have a headline statistic that nobody has re-measured in thirty years.
Links 03–04 quote the open-access full text of Gotvaldová et al., Int J Mol Sci 23(22):14068 (2022), PMID 36430546, PMC9693126. Link 05 reflects the absence of any PubMed-indexed primary source for the figure; Stamets & Gartz (1995) appeared in Integration, which is not indexed in PubMed.
The 0.38% psilocin and 0.35% baeocystin figures that circulate alongside it fare worse. They do not appear in Gotvaldová 2022 at all — not in the abstract, not in Table 1, not in the discussion. They come from the same original description, and no accessible peer-reviewed source has re-measured them.
What the Largest Modern Dataset Actually Shows
Gotvaldová and colleagues quantified five tryptamine alkaloids — psilocybin, psilocin, baeocystin, norbaeocystin, and aeruginascin — across 226 fruiting bodies from 82 individual collections spanning seven genera, using ultra-high performance liquid chromatography with tandem mass spectrometry. Most collections were vouchered by fungarium specimens and confirmed by ITS rDNA, LSU, or EF1-α sequencing.[1]
Plotting every psilocybin range they measured against the azurescens figure they only cited reframes the potency question considerably.
Measured vs Reported
Every Psilocybin Range Gotvaldová 2022 Actually Quantified
Solid bars are measured concentration ranges from 226 fruiting bodies analysed by UHPLC–MS/MS. The hatched marker is P. azurescens — the one value on this chart that the study cites from prior literature rather than measures. The “most potent species” claim is a comparison against bars that were never run side by side.
reported only — not sampled in this study
highest value measured in the entire dataset
the comparison baseline
Vertical rule marks 10 mg/g = 1% by dry weight.
17.8 ÷ 3.509 = 5.07×
The azurescens figure against the highest measured cubensis value in this study. The familiar “4 to 5 times cubensis” holds up.
17.8 ÷ 15.543 = 1.15×
The same figure against the highest value anyone in this study actually measured. The gap between azurescens and the field is a 15% edge, not a category of its own.
All measured ranges from Gotvaldová et al., Int J Mol Sci 23(22):14068 (2022), PMID 36430546, Table 1 and species discussion; n = fruiting bodies / collections. The azurescens value is the 17.8 mg/g figure that paper cites from the original species description (Stamets & Gartz 1995) and does not itself measure. Ranges are within-species spreads, not means, and the study emphasises that tryptamine content is “extremely variable” between individual fruiting bodies.
Two things follow. First, the familiar comparison to cubensis survives: measured cubensis in this study ran 0.651–3.509 mg/g psilocybin, so the 17.8 mg/g azurescens benchmark is about five times the top of that range. "Four to five times cubensis" is a fair statement.
Second, the stronger claim does not survive. P. serbica var. bohemica measured up to 15.543 mg/g, var. moravica up to 14.158, P. cyanescens up to 13.808, and P. semilanceata up to 11.421. Azurescens leads that field by roughly 15% on a number nobody in the study measured. It is at the top of a crowded distribution, not alone above it.
The variability caveat runs through all of this. Bigwood and Beug's 1982 study of P. cubensis grown in controlled culture found psilocin generally absent from the first flush and sometimes the second, reaching a maximum by the fourth, while psilocybin showed no directional trend across flushes but varied by a factor of four. Samples from outside sources varied by over a factor of ten between collections.[2]
Goff and colleagues' 2024 LC–MS/MS quantification of multiple P. cubensis strains found substantial variation between named strains under controlled laboratory conditions, and reported improved precision only when multiple mushrooms were homogenised together before extraction.[3] Both studies examined cubensis, but the principle is general: a single peak value describes what a species can reach, not what a specimen contains.
Cohen and colleagues' 2025 analysis of 42 psilocybin-producing fungal strains across nine species found that metabolite profiles cluster in species-specific ways rather than forming one continuous distribution.[4] That supports the general principle that species differ chemically in structured ways — but it says nothing specific about azurescens, which was not among the nine species examined.
What the Baeocystin Content Actually Means
The reported 0.35% baeocystin content is the basis for a common secondary claim: that azurescens produces a qualitatively different experience because of its unusual alkaloid ratio. Two preclinical papers are usually cited. Read directly, neither supports that inference.
Glatfelter and colleagues' 2022 structure-activity study tested psilocybin, baeocystin, and aeruginascin alongside their 4-acetoxy and 4-hydroxy analogues in mice. Broad radioligand screening found nanomolar affinity for most human 5-HT subtypes tested, including 5-HT2A and 5-HT1A. But on the behavioural endpoint that matters, the result was specific: only the tertiary amines — psilocin, psilocybin, and psilacetin — induced head twitch responses, the standard rodent proxy for psychedelic-like activity.[5] Baeocystin is a secondary amine, and falls outside that set.
Rakoczy and colleagues' 2024 characterisation in the British Journal of Pharmacology reached a compatible conclusion by a different route. All the compounds tested were dephosphorylated and metabolised at near-identical rates. The dephosphorylated products of baeocystin and norbaeocystin crossed a blood–brain barrier mimetic comparably to psilocin. But behaviourally, only psilocybin induced head twitch responses in rats.[6]
Evidence Reach Ladder
How Far the Baeocystin Evidence Actually Reaches
The high baeocystin content of P. azurescens is usually offered as evidence that the species produces a different kind of experience. Reading the two papers most often cited for that claim, baeocystin clears the pharmacokinetic rungs and then stops at exactly the rung that would matter.
| What was tested | Psilocybin | Baeocystin | Norbaeocystin |
|---|---|---|---|
Metabolised like psilocybin Near-identical dephosphorylation by alkaline phosphatase and MAO metabolism | demonstrated | demonstrated | demonstrated |
Crosses a blood–brain barrier mimetic Dephosphorylated form, compared against psilocin | demonstrated | demonstrated | demonstrated |
Activates 5-HT2A in vitro Cell imaging assay, efficacy compared to psilocin and norpsilocin | demonstrated | partial | demonstrated |
Head twitch response in vivo The standard rodent proxy for 5-HT2A-mediated psychedelic effects | demonstrated | not observed | not observed |
Antidepressant-like effect (forced swim test) Rakoczy 2024, rats | demonstrated | not tested | demonstrated |
Any human data Controlled trials of isolated minor tryptamines, or of high- vs low-baeocystin species | demonstrated | not observed | not observed |
The asymmetry worth noticing: the compound carrying the interesting in vivo signal in Rakoczy 2024 is norbaeocystin — it activated 5-HT2A like psilocin and improved forced swim test outcomes. Baeocystin is the compound P. azurescens is known for, and it is the one that did neither. Rakoczy's own stated conclusion is that these tryptamines may share therapeutic potential with psilocybin “but without causing hallucinations.” That is close to the opposite of “azurescens hits differently because of its baeocystin.”
Sources: Glatfelter et al., ACS Pharmacol Transl Sci 5(11):1181–1196 (2022), PMID 36407948 (mice); Rakoczy et al., Br J Pharmacol 181(19):3627–3641 (2024), PMID 38825326 (rats). Both are preclinical. “Partial” for baeocystin at 5-HT2A reflects Glatfelter's finding of nanomolar affinity across 5-HT subtypes for 4-hydroxy/4-acetoxy secondary amines without corresponding head twitch activity. No controlled human trial has compared species with high and low baeocystin content.
There is a further asymmetry that the popular framing misses entirely. The compound carrying the interesting in vivo signal in Rakoczy's work is norbaeocystin, not baeocystin: dephosphorylated norbaeocystin activated 5-HT2A with efficacy similar to psilocin, and, like psilocybin, improved outcomes in the forced swim test. Baeocystin — the compound azurescens is characterised by — did neither. The paper's stated conclusion is that these tryptamines "may share overlapping therapeutic potential with psilocybin, but without causing hallucinations."
So the honest reading is close to the inverse of the folk claim. Baeocystin is not inert, and it is not pharmacologically identical to psilocybin. But the preclinical evidence points toward it not contributing psychedelic-like activity, rather than toward it making azurescens hit differently. No controlled human trial has compared species with high and low baeocystin content, and none of this has been tested in people.
Storage and handling shift the picture further. Gotvaldová and colleagues' 2021 stability study of P. cubensis found that caps carried roughly twice the tryptamine content of stipes (1.03% versus 0.52% by weight, though not statistically significant given the variability), and that degradation depended strongly on storage: the greatest losses occurred in fresh mushrooms stored at −80°C, and the lowest in dried biomass kept in the dark at room temperature.[7] Any figure measured on a specimen decades ago describes that specimen's handling history as much as its species.
Where Psilocybe azurescens Grows — Habitat and Range
Psilocybe azurescens is native to the Pacific Northwest coast of the United States, with its type locality near Astoria, Oregon. It grows in a narrow ecological window: sandy, well-drained soils in coastal areas, with abundant decomposing alder, cottonwood, and conifer wood. Wood chip mulch in landscaped areas, dune grass margins, and riparian zones near the coast create the specific conditions it prefers. Fruiting season runs from late September through early December in its native range.
The common name "flying saucer mushroom" describes the cap morphology. Azurescens develops a broadly convex cap that flattens and often becomes concave at maturity, with a distinct central bump called an umbo and a margin that becomes characteristically wavy and undulating as the fruiting body ages. The cap color is caramel to ochraceous brown when moist, fading to a pale cream or tan as it dries. Bluing when handled or cut is heavy, reflecting psilocin oxidation at sites of cellular damage.
Unlike P. cubensis, azurescens does not grow on dung or easily cultivated grain substrates. It requires wood-based substrates and cooler fruiting temperatures than the tropical cubensis — typically in the 7–15°C range. Commercial cultivation is uncommon. Most azurescens encountered outside its native range represents naturalized populations established through wood chip mulch in European gardens and other temperate maritime climates, rather than commercial production.
Van Court and colleagues' 2022 review of psilocybin-containing fungi noted that research attention has concentrated overwhelmingly on a small number of accessible species, leaving the wider diversity of psilocybin-producing fungi — including the lignicolous species — comparatively understudied.[8] That imbalance is the reason the azurescens chemistry rests on a single 1995 description in the first place. The weight of analytical work follows the most cultivated species, not the most potent one.
The Misidentification Problem — Why Visual ID Is Not Sufficient
The most practically important fact about P. azurescens is that reliable identification from visual characteristics alone is not achievable for this species complex.
Bradshaw and colleagues' 2022 study re-examined 94 Psilocybe fungarium specimens representing 18 species by DNA barcoding, evaluated tryptamine stability in 25 specimens across the most commonly vouchered species, and explored the metabolome of cultivated P. cubensis. Their conclusion was blunt: apart from a few well-known species, the taxonomic accuracy of specimen determinations is "largely unreliable, even at the genus level." They also documented substantial quantities of poor-quality and mislabeled sequence data in public repositories, and a scarcity of sequences derived from type specimens — problems that compound each other.[9]
These are formally collected, curated, institutionally housed specimens — the benchmark for documented material. If determinations at that standard are unreliable, field identification by non-specialists is considerably less dependable.
P. azurescens shares habitat and general appearance with several species in the wood-lover clade, including P. cyanescens, P. allenii, and P. baeocystis. All produce heavy bluing when damaged. All grow on woody debris in temperate coastal climates. All have broadly similar cap colors and shapes. The distinguishing characters — precise cap margin waviness, umbo morphology, gill attachment, spore print darkness, cheilocystidia shape — require experience and often microscopy to apply reliably.
This has a direct consequence for everything above. The potency figures attached to the azurescens name apply only to verified azurescens. A field specimen visually identified as azurescens may be cyanescens — which Gotvaldová measured at up to 13.808 mg/g, genuinely comparable — or allenii, or something else. Given that the azurescens benchmark itself rests on a single unreplicated source, applying it to an unverified specimen compounds one uncertainty with another.
ITS sequencing — using the Internal Transcribed Spacer region of fungal ribosomal DNA — is the reliable identification method for this complex. Multiple university mycology programs and private services process dried specimens. Visual identification alone, even by experienced foragers, does not resolve the cyanescens–azurescens–allenii complex with adequate confidence.
The companion piece on DNA testing for mushroom supplements covers how the same authentication technology applies to verifying species identity in commercial contexts. For an overview of toxic lookalikes that can be confused with wood-loving psilocybin species, the companion piece on deadly mushroom lookalikes covers the most dangerous visual confusions in temperate habitats.
Where Azurescens Fits in the Psilocybe Genus
Bradshaw and colleagues' 2024 PNAS study substantially improved the phylogeny of Psilocybe using shotgun sequencing of fungarium specimens, obtaining 71 metagenomes including 23 from type specimens, and conducting phylogenomic analysis of 2,983 single-copy gene families.[10]
One finding is frequently misreported and worth stating carefully. The paper notes that the psilocybin biosynthetic gene cluster is known for only five of roughly 165 Psilocybe species — four of which belong to a single one of the genus's two major clades. The "~165 species" figure is the estimated size of the genus, not a count of species with a confirmed gene cluster. The gap between those two numbers is the point the authors were making.
Their molecular clock analysis suggests the stem lineage of Psilocybe arose around 67 million years ago and diversified around 56 million years ago, and that psilocybin biosynthesis first arose in Psilocybe with four to five possible horizontal transfers to other mushrooms between 40 and 9 million years ago. The analysis also revealed two distinct gene orders within the biosynthetic cluster, corresponding to a deep split within the genus.[10]
Within that structure, azurescens belongs to the lignicolous group of wood-decomposing Psilocybe species, alongside P. cyanescens — its closest commonly encountered relative and, on measured data, its closest chemical peer. That grouping is ecologically and evolutionarily distinct from the dung-dwelling and grassland species like cubensis and semilanceata.
For a comparison with the other major high-potency species in the wood-lover clade, the companion piece on Psilocybe cyanescens (wavy cap) covers identification and potency data for the species most frequently confused with azurescens in the field. For a broader species overview with potency rankings, the companion piece on psilocybin content by species: a comprehensive potency guide covers the full comparative data. And the companion piece on why psilocybin potency varies so much between mushrooms covers the biological mechanisms behind intraspecies variation.
The Bottom Line
Psilocybe azurescens is widely described as the most potent psilocybin species, but the figure behind that claim — 1.78% psilocybin by dry weight — originates in the species' original 1995 description by Stamets and Gartz and has not been independently re-measured. Gotvaldová 2022, the largest tryptamine survey of the genus (226 fruiting bodies, 82 collections), cites the figure as a benchmark but did not sample azurescens; its own highest measured value was 15.543 mg/g in P. serbica var. bohemica, within 15% of the azurescens benchmark. Against measured cubensis (0.651–3.509 mg/g), the roughly 5× multiplier holds. The commonly quoted 0.38% psilocin and 0.35% baeocystin figures appear in no accessible modern analysis. The claim that high baeocystin makes azurescens qualitatively different is not supported: Glatfelter 2022 and Rakoczy 2024 both found baeocystin did not produce head twitch responses, and Rakoczy concluded these tryptamines may carry therapeutic potential without hallucinogenic effect. Bradshaw 2022 found determinations of 94 fungarium specimens largely unreliable even at genus level, so any potency figure applies only to DNA-verified material.
Frequently Asked Questions
Sources & References
- 1RTHM-00762·Gotvaldová, Klára et al. (2022). “Extensive Collection of Psychotropic Mushrooms with Determination of Their Tryptamine Alkaloids..” International journal of molecular sciences.Study breakdown →PubMed →↩
- 2RTHM-00003·Bigwood, J et al. (1982). “Variation of psilocybin and psilocin levels with repeated flushes (harvests) of mature sporocarps of Psilocybe cubensis (Earle) Singer..” Journal of ethnopharmacology.Study breakdown →PubMed →↩
- 3RTHM-00879·Goff, Roman et al. (2024). “Determination of psilocybin and psilocin content in multiple Psilocybe cubensis mushroom strains using liquid chromatography - tandem mass spectrometry..” Analytica chimica acta.Study breakdown →PubMed →↩
- 4RTHM-02069·Cohen, Jonathan et al. (2025). “Comprehensive analysis of 42 psilocybin-producing fungal strains reveals metabolite diversity and species-specific clusters..” Scientific reports.Study breakdown →PubMed →↩
- 5RTHM-00759·Glatfelter, Grant C et al. (2022). “Structure-Activity Relationships for Psilocybin, Baeocystin, Aeruginascin, and Related Analogues to Produce Pharmacological Effects in Mice..” ACS pharmacology & translational science.Study breakdown →PubMed →↩
- 6RTHM-00901·Rakoczy, Ryan J et al. (2024). “Pharmacological and behavioural effects of tryptamines present in psilocybin-containing mushrooms..” British journal of pharmacology.Study breakdown →PubMed →↩
- 7RTHM-00688·Gotvaldová, Klára et al. (2021). “Stability of psilocybin and its four analogs in the biomass of the psychotropic mushroom Psilocybe cubensis..” Drug testing and analysis.Study breakdown →PubMed →↩
- 8RTHM-01629·Van Court, R C et al. (2022). “Diversity, biology, and history of psilocybin-containing fungi: Suggestions for research and technological development..” Fungal biology.Study breakdown →PubMed →↩
- 9RTHM-01490·Bradshaw, Alexander J et al. (2022). “DNA Authentication and Chemical Analysis of Psilocybe Mushrooms Reveal Widespread Misdeterminations in Fungaria and Inconsistencies in Metabolites..” Applied and environmental microbiology.Study breakdown →PubMed →↩
- 10RTHM-00865·Bradshaw, Alexander J et al. (2024). “Phylogenomics of the psychoactive mushroom genus Psilocybe and evolution of the psilocybin biosynthetic gene cluster..” Proceedings of the National Academy of Sciences of the United States of America.Study breakdown →PubMed →↩