B+ (also written "B Plus") is one of the most-sold Psilocybe cubensis strains in the world, and for good reason. Its combination of large spore production, adaptability to varied growing conditions, and visually distinctive microscopy characteristics make it a staple for both first-time researchers and experienced taxonomists. This guide covers everything you need to know about B+ โ from its debated origins to its spore morphology under high magnification.
This guide is part of our strain series. If you're new to spore microscopy, start with how to use a spore syringe for microscopy. For a comparison of B+ alongside other top strains, see our Golden Teacher strain guide.
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Origin & history
The B+ strain was reportedly developed in the early 1990s by a Florida cultivator known online as "Mr. G." The "B" in the name is sometimes said to stand for "beautiful" โ a reference to the large, caramel-capped fruiting bodies the strain reliably produces. Whether that etymology is accurate or apocryphal is debated, but the strain's popularity is not: B+ became one of the most-traded specimens in amateur mycology circles throughout the late 1990s and 2000s.
One of the more interesting claims around B+ is that it was developed as a cross between Psilocybe cubensis and Psilocybe azurescens โ a wood-loving species with notably different spore morphology. Most mycologists consider this claim genetically improbable (the two species have different chromosome counts and significantly different genetic profiles), but it persists in the community. What's well-documented is that B+ expresses unusual phenotypic adaptability: it tolerates a wider range of temperatures and substrate conditions than most cubensis strains.
Physical characteristics
B+ is a large-fruiting strain. Key visible features:
- Cap (pileus): Broad and convex in youth, flattening with age. Color ranges from light caramel to dark chestnut brown, often with a distinct nipple-like umbo at the center of mature caps. Diameters of 50โ100mm are common.
- Stem (stipe): Thick, white to pale yellow, often โฅ8mm diameter. Typically longer than most cubensis strains โ 80โ150mm is typical. The stem bruises blue readily on impact.
- Gills: Dense, close-set, gray in youth, darkening to deep purple-black at maturity as spores develop.
- Veil: A thick, persistent partial veil that leaves a well-defined annulus on the stipe.
- Spore print: Dark purple-black, dense, produced reliably even from young fruiting bodies.
Under the microscope
B+ spores are among the easiest to identify in the P. cubensis group โ large, numerous, and clearly featured at 400ร and above.
- Size: 11โ17 ร 7โ12 ฮผm โ on the larger end of the cubensis range, which is part of why the strain produces such dense, dark spore prints.
- Shape: Subellipsoid to ellipsoid, slightly more rounded than Golden Teacher. The breadth-to-length ratio is notably high compared to other strains.
- Color: Deep purple-brown under transmitted light. The thick spore wall gives B+ a more opaque appearance than thinner-walled strains.
- Germ pore: Prominent, well-defined, consistent. B+ shows one of the clearest germ pore presentations in the species โ useful for teaching taxonomic identification to beginners.
- Surface: Smooth under oil immersion. No ornamentation distinguishable at 1000ร.
For a practical walkthrough of how to prepare slides and measure spores, see our microscopy research guide.
Genetics & related strains
Despite the azurescens hybrid claim, genetic analysis places B+ firmly within Psilocybe cubensis. Its unusually large fruiting bodies and adaptability likely reflect selective pressure during cultivation rather than interspecies hybridization.
Strains with documented genetic proximity or phenotypic similarity to B+:
- Tidal Wave: A B+ ร Penis Envy cross. Inherits B+'s large spore size and thick spore walls, with PE's denser potency profile. See our Tidal Wave strain guide.
- Golden Teacher: Often cited alongside B+ as the other "beginner-friendly" cubensis strain. GT has slightly smaller spores and a more predictable morphology. See Golden Teacher strain guide.
- Amazonian: Similar large-cap morphology, different spore color profile โ see Amazonian strain guide.
Research value
B+ is recommended for taxonomic beginners for three specific reasons:
- Large, clear germ pore. The germ pore is the single most important morphological feature for identifying Psilocybe genus spores โ and B+'s pore presentation is unusually unambiguous, making it ideal for first-time identification exercises.
- High spore density. A single B+ syringe yields dozens of dense fields, reducing the time spent searching for suitable specimens under the scope.
- Stable morphology. Less phenotypic drift than many strains โ a B+ spore looks like a B+ spore across samples, which makes it valuable for comparative studies.
Legal status
Psilocybe cubensis spores โ including B+ โ are legal to purchase and possess for microscopy research in 47 US states. Three states prohibit them: California, Idaho, and Georgia. Living mycelium is a separate legal question and federally controlled. For the full picture, see our Spore Law & Compliance page.
FAQ
Why is B+ recommended for beginners?
Two reasons: the spores are large and clearly structured (easy to find and identify at 400ร), and the strain produces abundant spore prints, meaning a single syringe gives you many sessions of clean material to work with.
How does B+ compare to Golden Teacher under a microscope?
B+ spores are slightly larger on average and show a more prominent germ pore. Golden Teacher has a more regular ellipsoid shape and slightly more transparent spore walls. Both are excellent teaching strains โ B+ is marginally easier to photograph at 1000ร due to its size.
Is the B+ ร azurescens claim true?
Almost certainly not. Interspecies hybridization between P. cubensis and P. azurescens would require compatible chromosome counts and mating types โ and there's no genetic evidence supporting the claim. B+ is most accurately described as a selected P. cubensis phenotype with unusual adaptability, not a hybrid.
Where can I buy B+ spore syringes?
Our B+ spore syringe is produced fresh to order in a sterile flow hood and ships within 1โ2 business days. Each 10ml syringe produces dozens of microscopy sessions when refrigerated.
Disclaimer: HelloSpore sells Psilocybe cubensis spore syringes strictly for microscopy, taxonomy, and educational research. We do not support or condone germination or cultivation of controlled species. Follow all local, state, and federal laws.