Quick answer: B+ is a named strain of Psilocybe cubensis that dates to the 1990s Florida hobbyist scene, where community lore credits a cultivator known as “Mr. G.” It has large caramel-brown caps, tall pale stems and a heavy spore drop, and it has been one of the most common strains for about 25 years. The old claim that B+ is a hybrid of two species is a myth: it is ordinary cubensis.
Spores are legal to buy for microscopy in 46 states. Germinating them is not, which is why nothing on this page is about cultivation.
Looking for B+ spores?
Our B+ spore syringe is a 10 cc syringe, and it ships the same business day. Orders over $100 ship free, and our spore syringe packs save you up to 40%.
Intended use. Our B+ spore syringes are sold for microscopy, taxonomy and educational use only. This guide covers the strain’s history, what the mushroom looks like, and what its spores look like under a microscope. It does not cover cultivation, effects or dosing, and we do not answer questions about them.
In this guide
- What B+ is
- History and origin
- The “azurescens hybrid” myth
- Why it is called B+
- What the mushroom looks like
- What B+ spores look like
- Related strains
- Legal status of B+ spores
- Frequently asked questions
- Sources
What B+ is
B+ (“B plus”) is a strain of Psilocybe cubensis, the same species as Golden Teacher, Jedi Mind Fuck and Penis Envy. Strain names are informal: there is no registry or type specimen, and genome sequencing published in Current Biology in 2023 found that cultivated cubensis lines descend from a handful of founders and are highly inbred. B+ earns its name by phenotype: it is a big, tall, classically proportioned cubensis that produces a heavy purple-brown spore print, which is one reason it became a catalog staple.
History and origin
B+ entered circulation in the 1990s. The story told in hobbyist forums since the early 2000s credits a Florida cultivator posting under the name “Mr. G,” who is said to have isolated the line from a Florida collection and released prints that spread quickly through the mail-order spore trade of the late 1990s. As with most strains of that era, the account rests on forum posts and retellings rather than any dated record, and “Mr. G” never published a first-hand history. What is documented is B+’s ubiquity: it appears in the earliest online spore catalogs and has been continuously offered by nearly every U.S. vendor since.
The “azurescens hybrid” myth
For years B+ was described, including by some vendors, as a hybrid between Psilocybe cubensis and Psilocybe azurescens, a wood-loving species from the Pacific Northwest. It is not, and it could not be. The two are separate species that do not interbreed, and B+ has every hallmark of plain cubensis: dung-loving habit, cubensis-sized purple-brown spores, and a cubensis genome in every sequencing effort that has included it. The azurescens-hybrid claim is usually traced to Mr. G, who reportedly sold B+ as a cross. If a listing still makes the claim, treat it as a sign the seller has not checked.
Why it is called B+
No one has documented what the name B+ stands for. The most common guess is that the “+” signaled an improved or selected line (“B, plus”). It is sometimes written “B Plus” or “B-Plus” in catalogs, all referring to the same strain.
What the mushroom looks like
- Cap: caramel to chestnut brown, often with a paler margin, drying to a lighter tan. Broadly convex to flat at maturity, frequently large, with a smooth surface that is sticky when damp. B+ caps tend to be among the broadest of the common strains.
- Gills: attached to the stem, closely spaced, gray when young and purple-brown when mature.
- Stem: tall and pale, white to cream, thickening toward the base, with a persistent ring dusted dark by spores. Handled areas bruise blue, a trait shared across the species.
- Spore print: dark purple-brown and unusually heavy, which is why B+ prints and syringes are so easy to find.
What B+ spores look like
At 400× B+ spores are textbook cubensis: smooth, thick-walled, subellipsoid with a germ pore, purple-brown singly and near black in mass, roughly 11–17 by 7–11 micrometers. They are not distinguishable from Golden Teacher or Jedi Mind Fuck spores by light microscopy. A B+ syringe typically carries a very heavy spore load.
Related strains
- Tidal Wave is widely reported as a cross of B+ and Penis Envy made in the late 2010s, and has become one of the most requested strains of the 2020s. Its unusual look (thick stems, wavy caps) comes from the Penis Envy side.
- Golden Teacher is the other 1980s–90s staple B+ is most often compared with; see our Golden Teacher guide.
Legal status of B+ spores
B+ spores contain no psilocybin or psilocin, so under federal law and the law of 46 states they are not a controlled substance; the DEA confirmed the federal position in writing in January 2024. California and Florida restrict spores, Georgia and Idaho ban them, and we do not ship Psilocybe spores to those four states. Germinating spores is illegal under federal law everywhere. Our state-by-state legal guide has every statute.
Frequently asked questions
What is the B+ mushroom?
A named strain of Psilocybe cubensis from the 1990s Florida hobbyist scene, known for broad caramel caps, tall pale stems and heavy spore production.
What is the B+ strain’s scientific name?
Psilocybe cubensis. “B+” is an informal strain name.
Is B+ a hybrid of cubensis and azurescens?
No. That claim circulated for years but is biologically impossible; B+ is ordinary Psilocybe cubensis.
Where did B+ come from?
Community lore credits a Florida cultivator known as “Mr. G” in the 1990s. No first-hand record exists.
Why is it called B+?
No one has documented what the name B+ stands for. The usual guess is that the plus sign marked a selected or improved line.
B+ vs. Golden Teacher: what is the difference?
Both are cubensis with golden-to-caramel caps. B+ tends to be taller with broader, browner caps and a heavier spore drop; Golden Teacher’s cap is more yellow-gold with a paler margin. Their spores are indistinguishable under a light microscope.
Are B+ spores legal?
Yes, for microscopy, in 46 states. Not in California, Florida, Georgia or Idaho, where we do not ship.
Do you sell B+ spores?
Yes. View our B+ spore syringe →
Sources
- McTaggart A.R. et al. (2023). “Domestication through clandestine cultivation constrained genetic diversity in magic mushrooms relative to naturalized populations.” Current Biology. doi:10.1016/j.cub.2023.10.059
- Kurzbaum E. et al. (2025). “Exploring Psilocybe cubensis Strains.” Journal of Fungi 11(2):99. PMC11856550 (lists B+ among the common strains and notes that strain knowledge is community-sourced).
- Stamets P. (1996). Psilocybin Mushrooms of the World. Ten Speed Press. (Species description and spore measurements for P. cubensis and P. azurescens.)
- DEA Diversion Control Division letter on the status of spores (January 2, 2024). PDF
B+ spore syringe
Our B+ spore syringe is a 10 cc syringe filled in our ISO-7 cleanroom, with a sterile needle included. Orders placed by 1 p.m. Eastern on a weekday ship the same day, to the 46 states where spores are legal. You get free shipping on orders over $100, up to 40% off with our 3-, 5- and 10-packs, and a 30-day warranty. It is sold for microscopy and taxonomy use only.
