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Psilocybe cubensis
Koh Samui
A Thai island cube tied to ethnomycologist John Allen's field trips, famous for stumpy thick stems and broad saucer caps. A standard heavy purple-brown print and clean, textbook spores.
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Sold for microscopy, taxonomy and collecting only. Not for cultivation.
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The short version
Koh Samui is a Psilocybe cubensis line linked to the Thai island of the same name, where ethnomycologist John W. Allen collected wild specimens in the late 1980s and 1990s. It is a plain cubensis, not a hybrid and not a separate species, known for short stocky stems, broad caramel caps and a dependable dark purple-brown spore drop. A handsome, easy-to-study collector's classic with a genuinely documented field origin.
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
- The name comes from Koh Samui, a tropical island in the Gulf of Thailand, where the line is said to trace back to wild specimens collected on the island.
- It is associated with the ethnomycologist John W. Allen (Mushroom John), who collected mushroom specimens across Thailand and Southeast Asia in the late 1980s and 1990s.
- Genetically it is a plain Psilocybe cubensis, not a hybrid and not a separate species.
- It is reported to come from dung in rice-paddy plots fed by water buffalo and cattle, which fits cubensis perfectly as a coprophilic, dung-loving mushroom.
- Its field reputation is for short, thick, stocky stems and broad saucer-like caps rather than the tall lanky build of many cubes.
- It drops a standard dark purple-brown spore print and deposits readily, which is exactly why collectors keep it on the shelf.
What the community says
- The 'Super Strain' or 'KSSS' label you often see is a vendor selection claim, said to be a larger and more vigorous pick from the original Koh Samui stock. Treat the upgrade as marketing rather than a separate documented lineage.
- Koh Samui the cubensis strain is frequently confused with Psilocybe samuiensis, a genuinely separate species from the same island. Allen co-described that species with Guzman and Bandala, but it is not this mushroom.
- Sub-names float around the hobby, from Koh Samui Classic to an albino version, and most are renamings rather than distinct documented stock.
- The exact collection date is told a few different ways, some accounts say 1989 to 1990, others just 'the nineties'. The island is solid, the calendar is fuzzy.
- It sometimes gets billed as an unusually potent Thai 'super' cube. A cube is a cube, and strain-to-strain strength claims are mostly cultivation talk, so take that one with salt.
The story
The cube with a real island behind it
Most cube names are folklore with the serial numbers filed off. Koh Samui is a nice change of pace, because there is a real place, a real collector, and a fairly clear paper trail behind it. By most accounts the line traces to the island of Koh Samui in the Gulf of Thailand, where the self-taught ethnomycologist John W. Allen, the man the hobby calls Mushroom John, was collecting wild specimens through the late 1980s and into the 1990s. He photographed, pressed and printed what he found, and several Thai cubensis lines that are still passed around today carry the names of the places he worked.
The substrate story is exactly what you would hope for from a cube. The mushrooms were reportedly found in rice-paddy plots fertilised by water buffalo and cattle, which is textbook habitat for a coprophilic, dung-loving species. Whether the stock circulating now is a faithful descendant of those exact prints or something that drifted over decades of hand-to-hand sharing is impossible to verify, so treat the unbroken-lineage version as community lore rather than gospel.
The island is documented, the collector is documented, but the chain from his 1990s prints to the syringe in your fridge is built on trust, not paperwork.
Samui the strain versus samuiensis the species
Here is the trap people fall into. Allen also co-described a genuinely separate species from the same island, Psilocybe samuiensis (Guzman, Bandala and Allen, published in the early 1990s), a small reddish-brown grassland mushroom of the sandy, clay-rich soil in those rice fields. That is not this mushroom. Koh Samui the strain is a plain Psilocybe cubensis that happens to share an address with samuiensis. Same island, two different fungi. And the popular "Super Strain" badge is a vendor's selection claim, apparently a bigger, more vigorous pick from the original stock, so read it as a grade rather than a new lineage.
The species
Meet Psilocybe cubensis
Koh Samui 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
- Koh Samui, 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.
Broad caramel cap
Bell-shaped and golden when young, opening to a wide, often saucer-like cap with a sometimes uplifted rim at maturity. Caramel to light golden-brown, occasionally with a darker centre.
Short, stocky stem
The signature of the line. The stipe runs notably thick and stumpy rather than tall and lanky, creamy white to faintly yellowish, with a partial veil leaving a ring once it tears.
Darkening gills
Pale grey and crowded when young, deepening through purple-grey to near-black as the spores ripen, eventually dusting the ring purple-brown.
Blue bruising
Handle the flesh and it bruises blue-green, the usual Psilocybe enzyme reaction. Classic cubensis behaviour, nothing strain-specific about it.
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
- Koh Samui (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
Further reading
Independent, non-commercial sources, no shops, just good information.
- Psilocybe cubensis on Wikipedia: the species overview.
- The genus Psilocybe: taxonomy and the family reshuffle.
- Index Fungorum: the formal nomenclature record.
- Proc. Royal Society B (2026): the African wild-relative study.
Common questions
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.
No, and this is the single most common mix-up. Psilocybe samuiensis is a separate small species that John Allen co-described from the same island. The Koh Samui you are looking at here is a plain Psilocybe cubensis that simply shares the place name. Same island, two different mushrooms.
Mostly a label. The 'Super Strain' or KSSS tag is a vendor's selection claim, said to be a larger, more vigorous pick from the original Koh Samui stock. It is best read as a grade rather than a separate documented lineage.
Smooth, subellipsoid, thick-walled spores with a flattened germ pore at one end, pale amber individually and dark purple-brown in a mass. Find them at 100x, study at 400x, and bring the wall up sharp at 1000x under oil immersion.
Yes. It deposits a standard dark purple-brown print and is a willing, heavy depositor, which is part of why it has stayed popular with collectors for decades. Kept cool, dark and dry, a print stores for study for years.
What customers say
Reviews
Perfect for microscopy work. Would highly recommend!
Great quality products.
Really disappointed. I bought 3 syringes which were all contaminated. When I complained and ask for a refund they ignored me. —- Our Response: Hi there, please make sure to give us enough time to reply to emails before jumping to conclusions. Also - if you’re wanting a quicker reply, do <strong>not</strong> choose ‘medium’ as the priority level! Select ‘high’ or ‘critical’… we deal with those first obviously. Thank you :)
Yes they work 👍
Simply banging
Would love to do this as a job
Reply from Cylocybe
Well you should definately aim for that :) Thank you for the great review!
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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.