Psilocybe Cubensis Spores UK | Catalogued Isolates

Psilocybe cubensis (Earle) Singer is the most widely studied member of the genus and the reference species for most spore microscopy. It is a dung-associated, pantropical species, described from Cuba in 1906, and it is the species behind almost every named strain in circulation.

Under the microscope cubensis spores are subellipsoid to ellipsoid in face view, thick-walled, and carry a distinct germ pore at the apex. Reference measurements put them at roughly 11-17 x 8-11 micrometres, which makes them comfortably resolvable at 400x and straightforward to measure at 1000x under oil. The spore print is a dark purple-brown, dark enough that print colour alone separates the species from most lookalikes.

What you are looking at on the slide

Work at 400x first to survey the field, then move to 1000x with oil for measurement against a stage micrometer. The germ pore is the feature worth finding: a distinct, flattened aperture at the apex of the spore, clearly visible as a lighter spot when the spore is oriented face-on.

Wall thickness is the other diagnostic. Cubensis spores are noticeably thick-walled compared with Panaeolus, which is the comparison most people are actually trying to make when they put both on a slide.

Isolates, crosses and why the names differ

A strain name in this catalogue means one of two things. Either it is an isolate, a line taken down to a single stable phenotype from a parent population, or it is a documented cross between two named parents. Where we know the cross, it is printed in the product name in brackets.

This matters for microscopy because an isolate gives you a far more uniform sample. A multispore syringe from the same parent will show you the whole genetic spread instead, which is interesting for a different reason.

Frequently asked

How big are Psilocybe cubensis spores?

Reference measurements put Psilocybe cubensis spores at roughly 11-17 micrometres long by 8-11 micrometres wide, subellipsoid in face view and thick-walled with a distinct germ pore. Measure at 1000x under oil against a stage micrometer.

What colour is a Psilocybe cubensis spore print?

Dark purple-brown to almost black. The print colour is one of the more reliable macroscopic characters for the species and separates it from most lookalikes.

Is Psilocybe cubensis found in the UK?

No. Psilocybe cubensis is a pantropical, dung-associated species and does not occur naturally in the British Isles. The Psilocybe species that do occur here are semilanceata, cyanescens and a small number of others, which we cover in our UK species guide.

Are Psilocybe cubensis spores legal in the UK?

The spores themselves contain no psilocybin or psilocin and are not controlled under the Misuse of Drugs Act 1971. They are lawful to supply and possess for microscopy and research. Cultivating them is not, because the resulting fungus is a Class A drug.

What does iso mean in a strain name?

It marks an isolate: a line taken down to a single stable phenotype rather than left as a multispore mix. Isolates give a far more uniform sample on the slide.