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Yosterizii

Psilocybe cubensis

Yosterizii

A short, stubby Ecuador substrain with a wood-grained cap, named after the contested forum figure who put it out. Well-pigmented spores and a backstory that is half mycology, half message-board drama.

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The short version

Yosterizii is a Psilocybe cubensis line said to be a substrain of the South American Ecuador strain, named for a forum figure called Dr Yoster who reportedly spent about three years working on it. It is remembered as much for the arguments around its creator as for the mushroom: small, stubby fruits with a wood-grained cap that sometimes skips its veil ring. The spores are ordinary cubensis, well-pigmented and worth a slide.

Straight talk

Fact vs. legend

There is a lot of folklore around this strain. Here is which bits are real, side by side.

What we actually know

By most accounts Yosterizii is presented as a substrain of the Ecuador (EQ) line, a South American cubensis, rather than its own species or a hybrid.
Genetically it is plain Psilocybe cubensis, with nothing exotic in the family tree.
The name traces to a Shroomery-era handle, Dr Yoster, who is said to have worked on the line for around three years before circulating it.
Growers who studied it reported a wood-grained, lined cap and short, stubby fruits with solid stems, with some specimens lacking the usual veil ring (annulus).
Being a normal Ecuador-type cubensis, it deposits a standard dark purple-brown spore print and bruises blue-green like any other cube.
Independent of any vendor hype, strain-to-strain potency differences in cubensis are largely cultivation-driven. As the hobby saying goes, a cube is a cube.

What the community says

The headline claim, reportedly from Dr Yoster, that it took three years to perfect and would throw a flush every two weeks for six months, is unverified vendor and forum lore, not documented fact.
Some long-time forum members flatly dismissed it, calling it bull and saying it was probably just another cubensis substrain with a new name on it. Treat the dispute as community lore on both sides.
There is a persistent message-board story that Yosterizii was being resold under the name Oracle. The warning itself came from Dr Yoster, who offered no proof and was asked for it.
The name appears to be nothing more exotic than the creator's own handle with a mock-Latin tail stuck on it, in the style of a species epithet. Treat that as the likely reading, not a settled fact.

The story

The cube named after the man, and the man named after nobody

Most famous cubes are named for a place, a colour or a joke. Yosterizii is named for a person, or at least a forum handle: Dr Yoster, who turned up on the old mushroom message boards in the mid-2000s and is said to have spent roughly three years working on a line he then circulated as his own. By most accounts it began as a selection out of the South American Ecuador (EQ) strain, which makes Yosterizii a substrain rather than anything genuinely new under the sun.

What happened next is the interesting part, and almost none of it is about the mushroom. Dr Yoster became a contested figure. Some growers reported good results and treated the line as legitimate. Others were blunt, calling the whole thing fiction and saying Yosterizii was probably just another cubensis with a fresh label and a long sales pitch attached. The truth is somewhere in the noise, and we would rather tell you the noise is there than pretend it isn't.

The version is that Yosterizii is a real, ordinary Ecuador-type cubensis wrapped in an unusually loud origin story. The mushroom is calmer than its reputation.

The Oracle muddle

There is one more wrinkle worth knowing about, because it tells you how tangled strain names get once they leave the person who coined them. The story goes that Yosterizii was, at some point, being resold under the name Oracle. The catch is that the warning about it apparently came from Dr Yoster himself, and he was promptly asked for proof he never produced. Whether it was relabelling, a feud, or both, it is a tidy reminder that a cubensis "strain" is really just a name people agree to use, and those names drift, split and get borrowed all the time.

The species

Meet Psilocybe cubensis

Yosterizii is a collector’s line of a single, well-travelled species. Psilocybe cubensis was first written up in 1906 by the American mycologist Franklin Sumner Earle, from a specimen found in a cattle field in Cuba, which is where the name comes from. He originally called it Stropharia cubensis; Rolf Singer moved it into the genus Psilocybe in 1948.

The genus name is a tidy bit of Greek: psilos (“bare”) plus kubē (“head”), for the smooth, peelable skin of the cap, so the full name reads roughly as “the bare-headed mushroom from Cuba.”

Family: Hymenogastraceae (older books say Strophariaceae)
Genus: Psilocybe (Fr.) P. Kumm., 1871
Species: Psilocybe cubensis (Earle) Singer, 1948
Basionym: Stropharia cubensis Earle, 1906
This product: Yosterizii, a collector’s cultivar of the species
Type locality: Cuba (where it was first named)

How you’d know it

Field marks

These describe the mature mushroom for reference and identification.

Wood-grained cap

The signature mark people point to: a cap that often shows faint wood-grain streaking or fine radial lines rather than a flat, even colour. Otherwise a standard golden to caramel-brown cube cap, paler at the rim.

Short, stubby build

Reportedly grows on the squat side, with solid, fairly thick stems and compact fruits rather than the tall, lanky look some cubes throw. Early flushes were described as notably small.

Sometimes no ring

Most cubes keep a persistent membranous ring (annulus) where the partial veil tears. Yosterizii specimens reportedly skip it more often than usual, leaving the upper stem bare. Variable, not guaranteed.

Blue bruising and dark gills

Crowded gills go from pale grey to near-black as spores ripen, and handled flesh bruises blue-green, the classic Psilocybe enzyme reaction. Nothing unusual here, which is the point.

Where it comes from

A dung-lover with a wanderer’s history

Psilocybe cubensis is coprophilic, a fancy word for dung-loving. In the wild it lives on the droppings of big grazing animals, classically cattle and water buffalo, fruiting from warm, humid pasture. It does not grow on wood and it does not partner with tree roots.

You’ll find it across the warm parts of the world: the Gulf Coast of the United States, Mexico, Central and South America, Southeast Asia and Australia. It was named from Cuba, but where the lineage truly began is an open question. A 2026 study describing its closest wild relative in southern Africa suggests the deep roots are Old-World, the mushroom having apparently travelled with grazing herds long before anyone gave it a Latin name.

The main event

Under the microscope

This is what you actually bought the spores for. Put a print or a drop from a syringe on a slide and here’s what shows up.

Shape & size. Smooth, thick-walled and subellipsoid, like a slightly squashed rugby ball, roughly 11.5–17 µm long by 8–11 µm wide (the figures Paul Stamets settled on).
The germ pore. Look for a single pale, flattened dot at one end. That’s the one thin spot in the wall where, in nature, a mushroom would begin, and a real cubensis hallmark.
Pale alone, dark in a crowd. A single spore looks honey-amber with the light behind it; only in a mass do they read deep purple-brown to black. So a near-black print but pale spores on the slide is normal optics, not a dud.
What you’ll need. Find the field at 100×, study shape and the germ pore at 400×, and get the wall crisp at 1000× under oil. A touch of methylene blue or KOH lifts the contrast.
The legal bit, and why it’s true. A dormant spore carries no psilocybin or psilocin at all; that chemistry only appears later in living tissue. That is exactly why the spores are legal to own and study in the UK.

Choose your format

Print, syringe, vial or swab?

Same lab-grade genetics in every option. The honest difference is shelf life versus how soon you’re at the scope.

Spore print

Keeps longest

Spores dropped straight onto sterile foil. Stored cool and dry it outlasts everything else here, so it’s the one to reach for if you’re building a collection to keep for years.

Spore syringe

Ready tonight

Spores suspended in sterile water, ready to go straight onto a slide. The quickest way to be looking down the microscope this evening. Comes in 3 mL and 12 mL.

Vial & swab

Compact

A sealed glass vial is a tidy middle ground; a sterile swab is the most travel-friendly, robust little format for adding a strain to your reference set.

At a glance

The spec sheet

Species: Psilocybe cubensis
Strain: Yosterizii (collector’s cultivar)
Spore print: Dark purple-brown to near-black, heavy depositor
Spore shape: Subellipsoid, smooth, thick-walled, with a germ pore
Spore size: ~11.5–17 × 8–11 µm
Basidia: Mostly 4-spored, ~20–30 × 7–10 µm
Wild habitat: Coprophilic, on herbivore dung & warm pasture
Climate: Subtropical to tropical
Intended use: Microscopy, research & collecting only

Dig deeper

Frequently asked

Yes, for microscopy and research. A dormant spore contains no psilocybin or psilocin, so the spores themselves are not a controlled substance in the UK. We sell them strictly for microscopy, taxonomy and collecting, never for cultivation.

That has been argued both ways for years. It is presented as an Ecuador substrain, and some collectors treat it as its own line while others say it is plain Ecuador with a new name. Genetically it is ordinary Psilocybe cubensis either way, so for study purposes the label matters less than what is on the slide.

A mushroom-forum handle from the mid-2000s credited with circulating the line, reportedly after a few years of work. He became a contested figure, praised by some and dismissed as a scammer by others. We pass that on as community lore, because the documented record is thin and we are not going to pretend otherwise.

Standard cubensis spores: smooth, subellipsoid and thick-walled, pale amber on their own and dark purple-brown in a mass, each with a small flattened germ pore at one end. Find them at 100x, study at 400x, and bring the wall up sharp at 1000x under oil.

A normal, well-pigmented cube print: dark purple-brown to nearly black, and it deposits readily. This is not an albino or leucistic line, so you get a proper dark, dense print rather than a faint one.

Cool, dark and dry. A fridge (not freezer) suits syringes and vials; a print keeps happily in a sealed bag somewhere cool. Stored well, a print stays viable for study for years.

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Questions and answers

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For microscopy, taxonomy and collecting only.Sold for legal research. Not for cultivation. Spores contain no controlled substances. We trust you to be responsible.