What Jack Frost is
Jack Frost is an albino Psilocybe cubensis cross, usually described as True Albino Teacher crossed with Albino Penis Envy and credited to the breeder Dave Wombat. Dino Spores and Fungus Frequency both list it that way, and the pedigree is repeated widely enough that most people treat it as settled, even though nobody has published it formally. The name describes the fruit: white from base to cap, with caps that often take on a frosted, crystalline look as they mature, and gills that Fungus Frequency describes as "bright blue".
Both parents matter for what follows. True Albino Teacher (TAT) is an albino isolate out of Golden Teacher, and Albino Penis Envy (APE) is the pale form of Penis Envy. Put two albino lines together and you get an albino child, which is why Jack Frost has become the starting point for so many white crosses since.
Under the microscope it is a true albino: Sporeworks notes that Jack Frost, Pearly Gates and TAT all produce non-pigmented, translucent spores at maturity. The print is faint, the syringe looks almost clear, and you will want low light or a stain to pick the spores out. The spores themselves are ordinary cubensis, subellipsoid and in the usual size range. Jack Frost is listed by Dino Spores, Fungus Frequency, CB Shroomy, SummerBreeze and Sporeworks as isolate syringes, swabs, liquid cultures and research plates, so it is one of the easier lines on the site to find.
How a cross gets its name
Most of the names below follow three habits, and once you can see them the family tree reads itself.
- Parent x parent. The "x" means crossed with. There is no agreed rule about which parent is written first, so Toque x Jack Frost and FROTO (listed as Jack Frost x Toque) describe the same pairing in opposite order, made by different people.
- A blended word. ToqueJack, FROTO and Frosty Pearlz are portmanteaus. This is also why a word like "Frost" in a name usually signals Jack Frost somewhere in the pedigree, in the same way "Gates" signals the Gates lines.
- A tag on the parent name. Isolations keep the parent's name and add a tag: Permafrost, Jack Frost 2.0, Frost 324. A number is a catalogue mark for one particular isolate. What The Fungi notes Frosty Pearlz 393 as a 393g iso, meaning the number is the weight of the specimen the clone was taken from, so the same style of number can mean different things from different vendors.
Two more terms turn up on these labels. An F number (F6, F7) is the generation count, which the Toque post explains in full. A di-mon cross, the term Dino Spores uses for Shiva, pairs a monokaryon (a culture grown from a single spore) with a dikaryon (an already mated culture) rather than letting two spore batches mix at random, which gives the breeder more say over which parent contributes what.
Why the frosty white look keeps coming back
Albinism in cubensis is a missing-pigment trait, and breeders treat it as recessive: cross two albino lines and the offspring stay white, cross an albino with a pigmented line and colour usually comes back in the first generation, with white forms reappearing only in later selections. Jack Frost is albino on both sides, so any cross that pairs it with another albino line stays frosty. Star Frost (Jack Frost x Starry Night APE), Frosty Pearlz (Jack Frost x Pearly Gates) and Icy Gates (Lucid Gates x Iceberg) all pair pale with pale, and all come out white.
The blue is part of the same picture. Cubensis tissue bruises blue when handled, and on a white fruit that shows far more clearly than on a brown one, so blue gills, blue caps and intense blue bruising turn up in vendor notes right across the family. Cross Jack Frost with something pigmented, as Yellow Umbo does, and the colour returns, which is one reason that hybrid is interesting to look at under the scope.
Jack Frost isolations and re-selections
These carry Jack Frost genetics without a second parent. Each is one individual picked out of the line and kept as a clone, which is what iso means on a label (see isolated vs multispore syringes).
Jack Frost 2.0 is Telly Monster Myco's re-selection, described as an albino line derived from Jack Frost with "frosted white fruits, thick stems, and upturned caps with intense blue bruising". Permafrost is listed by Dino Spores as a Jack Frost isolation by Dave Wombat himself. Frost 324 is What The Fungi's isolate, picked out first for full albinism and later for size; the vendor says some specimens show the blue-gilled canopy and some do not. BrainFrost is sold by Mr. Rogers Labz as liquid culture and described simply as a Jack Frost mutant, a brain-like growth form kept as a clone.
Frostbite and Frost Squat are agar plates from Teche Genetics with no lineage written on the listing. The names follow the convention, Frost for the parent and a tag for the selection, and squat is the usual word for a short, wide fruit with a thick stem, the same sense it carries in the Mak family.
The Jack Frost crosses, line by line
Crosses with other albino lines
Star Frost pairs Jack Frost with Starry Night APE, the dark-capped APE isolate sold as SNAPE. Fungus Frequency credits the cross to Monokaryon MyWaywardson and describes dense, fat albino fruit with blue caps. It is listed by Black Forest Cultures, Fungus Frequency and Dino Spores, which makes it the most widely listed cross in the family.
Frosty Pearlz 393 is What The Fungi's original cross of Jack Frost and Pearly Gates, made, the listing says, from a monokaryotised culture of each parent. Pearly Gates is itself a TAT cross, so this is TAT genetics meeting TAT genetics from two directions.
Icy Gates is Telly Monster Myco's cross of Lucid Gates and Iceberg, which the vendor describes as merging "the Penis Envy / True Albino Teacher lineage with the Jack Frost / Albino lineage". Fungus Frequency lists Iceberg as an albino isolation of the Thai landrace Lipa Yai, so how much Jack Frost is actually in Icy Gates depends on whose account you follow. It belongs on this tree by name and by look, with the pedigree marked as the vendor's.
Crosses with pigmented and mutant lines
Shiva is Jack Frost x Shakti. Dino Spores lists it as a di-mon cross by Yoshi Amano, a Jack Frost monokaryon paired with a dikaryon of Shakti Blue Mutant, and offers it at F6 as swabs and F7 as isolated syringes. Shakti is a pale Malabar Coast isolate, so this is pale meeting pale again, with the blue mutant's odd forms in the mix.
Three labels cover Jack Frost crossed with Toque, the stacked-cap Tidal Wave isolation. FROTO is What The Fungi's in-house cross, listed as Jack Frost x Toque. Toque x Jack Frost is an isolated syringe listed by Mushrealm and Mushrealm UK. ToqueJack is a Black Forest Cultures research plate of what the vendor calls the original Toque x Jack Frost developed by Dave Wombat, passed on by Dichotomous Keys. Same pairing, three separate crosses, so expect three different looks.
Yellow Umbo is the odd one out: a cross between two species, Psilocybe ochraceocentrata and Psilocybe cubensis "Jack Frost". Dino Spores describes it as the first documented hybrid of cubensis with another species, made by Yoshi by pairing monokaryons of each species that were gathered through serial streaking on agar. It is listed at F7 as isolated syringes and swabs. The same project produced Low Spore Umbo, an isolation that drops far fewer spores; the vendor assumed it was sterile until microscopy showed mature, pigmented spores on the gills. For anyone who studies spores, a cubensis hybrid that carries ochraceocentrata pigment is worth a slide of its own.
Bi Frost sounds like a Jack Frost line and is not one, at least by the vendor's account. Fungus Frequency lists it as a PsyTeamUnited cross of ochraceocentrata with SV-13. It sits here as a warning that Frost in a name is a strong hint, not a guarantee; read the listing.
Reading a Jack Frost label
Whatever the line, the label should tell you three things: whether the syringe is an isolate or multispore, the generation if the vendor knows it, and the parentage as that vendor understands it. Treat every pedigree above as the listing's own account, because none of them is documented outside the hobby. A clear syringe is normal for this family and not a sign of an empty one; the spores are there, they just carry no colour.
Psilocybe and Panaeolus spores on Culture Cave are sold for microscopy and taxonomy use only, and buyers must know their local law before they order; the UK legality guide covers the basics for British buyers.