What lab studies say about differences between cubensis strains

The question, and why it is hard to answer

Shops and forums describe McKennaii with words such as "strong" or "potent". To test that, a study would need several cultures sold as McKennaii, grown side by side with other cultivars under the same conditions, dried the same way and analysed with one validated method, with single mushrooms measured separately. For McKennaii that study does not exist. For a handful of other strains, it does, and those results set the limits on what any strain name can tell you.

Five strains, one method

A group at the University of Texas at Arlington developed a liquid chromatography and tandem mass spectrometry method and applied it to five dried strains, analysing three whole mushrooms per strain (Goff et al., 2024¹). A second, independent laboratory measured part of the material and found comparable results.

Table 1. Average psilocybin plus psilocin in five P. cubensis strains, as percentage of dry weight (Goff et al., 2024).

The spread between the highest and lowest strain is about 1.5-fold. The authors also noted that measurements became more precise when several mushrooms were ground together before extraction, which is a sign that single mushrooms differ.

Fourteen strains under identical conditions

A 2026 study from the University of Haifa grew 14 cubensis strains under identical conditions, each in its own growth chamber on the same substrate, and dried and analysed them in the same way (Sharchaton et al., 2026²). DNA sequencing of the ITS region confirmed that all 14 were P. cubensis.

Table 2. Total tryptamines in dried fruit bodies, selected strains (Sharchaton et al., 2026).

Across all 14 strains, total tryptamines ranged from 2.62 to 20.65 mg per gram, a difference of more than sevenfold. Psilocybin was the main compound in every strain. When five single mushrooms of the same strain were measured separately, the coefficient of variation for psilocybin was 12.8 to 23.4%. Mushrooms of one strain, grown in one chamber and harvested together, still differed noticeably from each other.

Golden Teacher itself was not tested, only a cross that includes it. McKennaii was not in the study.

Flush to flush

An older study grew P. cubensis in controlled culture and followed it through repeated harvests (Bigwood and Beug, 1982³). Psilocybin varied by up to a factor of four between flushes, without a clear upward or downward trend. Psilocin was generally absent in the first flush and peaked by the fourth. Samples from outside sources differed by more than a factor of ten. Harvest, drying and storage matter as much as the name.

Storage

A Czech study measured how psilocybin and related compounds break down in P. cubensis biomass (Gotvaldová et al., 2021⁴). Losses were largest in fresh mushrooms stored at minus 80 °C and smallest in dried material kept in the dark at room temperature. The same study found no tryptamines in the spores. A strain comparison that ignores storage is comparing storage as much as genetics.

What the genome data add

A 2023 genome study of 86 commercial cultivars found low genetic diversity and identical alleles in the psilocybin gene cluster in most of them (McTaggart et al., 2023⁵). The authors suggest that the rarer variants, found in Australian wild isolates and some cultivars, may lead to differences in psilocybin biosynthesis. Taken with the chemistry above, this suggests that many cultivar names cover closely related cultures, while some genuine differences exist between lines.

What this means for McKennaii

• The name does not come with a measured content. Descriptions of its strength are anecdote.
• Even if McKennaii were measured, single mushrooms and single harvests would vary by tens of percent.
• The only laboratory paper we found that used McKennaii material was an analytical methods study from Amsterdam. It used an extract as test material for a screening technique and did not report its psilocybin content (Otvos et al., 2016⁶).
• A 2025 review notes that most descriptions of named strains come from non-academic, community-based reports (Kurzbaum et al., 2025⁷).

How the species is defined is covered in what McKennaii is. What these numbers mean for the experience itself is in effects and safety.