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Testing & Processing Classification, Omics, Cannabinoid analysis

Not as Advertised

Product consistency is an accepted consumer expectation. “Take apples, for example,” says Anna Schwabe, a Research Coordinator at Mile High Labs. “Consumers have a level of expectation of what a Granny Smith apple is: green, crunchy, and tart. Each apple is not identical, but there are common features that make a Granny Smith apple a Granny Smith apple.”

When it comes to cannabis, plants labeled as a given strain should demonstrate a similar phenotype – and thus exert similar effects when consumed – somewhat irrespective of the seller… in theory.

Schwabe first became suspicious of dispensary claims when her friend found a cannabis strain she adored, and yet experienced different effects when buying “the same strain” from other sellers. Later, “the same strain” from the original dispensary wasn’t quite hitting the spot. Given a background in population genetics, Schwabe is well aware that some phenotypic variation is a given. “Phenotype is a product of the environment and the genotype. We know that grow facilities don’t follow the same protocols; plants are grown under slightly different conditions (soil, water, nutrients, harvest time, storage, and so on), and that can lead to variation in phenotypes (as with Granny Smith apples), but to what extent?” asks Schwabe. “And what if it isn’t just different growing conditions? What if dispensaries really do have plants that are genetically different but labeled with the same name? And, if they do, how would they even know?” She decided to explore (1).

With co-investigator Mitchell McGlaughlin, Schwabe collected 122 cannabis samples across 30 strains from 20 recreational and medical dispensaries across Colorado, California and Washington. When asked why they didn’t declare the nature of their study to the dispensaries, Schwabe says, “We wanted to know what consumers were being provided with – and we believe this research is especially valuable for those using cannabis for medicinal purposes.”

DNA was extracted from each sample and assessed for genetic similarity within labeled strains. Their alignment with purported proportions of genes belonging to typical Sativa- and Indica-type plants were also assessed to investigate the true value of these distinctions among tested strains.

So, what did they find? Some strains were cohesive – though Schwabe notes that would probably not be the case if further samples were added for under-represented strains. Specifically, Jack Flash (n = 2), Island Sweet Skunk (n = 3) and Chemdawg (n = 7) all displayed over 90 percent similarity. Blue Dream (n = 9) and Durban Poison (n = 9) samples were 89 percent similar – but the two strains each harbored one genetic outlier. Schwabe summarized: “27 of 30 strains had at least one genetic outlier, indicating there are substantial genetic differences within strains that are largely propagated from cloning methods.”

Sativa, Indica and hybrid plants were also poorly defined at a genetic level. The likely reason? “Extensive hybridization and selection leading to homogenization and erased evidence of potentially divergent historic phenotypes,” says Schwabe.

The extent of genetic variation observed highlights the need for aligned product verification in the cannabis industry. Schwabe offers a solution for part of that problem: “Industry standard regulatory checks should be implemented in the form of genetic testing to provide consistency, especially for medical applications [...] How will you ever provide consistency without first making sure you have what you think you have?”

As for Schwabe’s friend… “She is still hunting for the elusive perfect strain she found so many years ago.”

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  1. AL Schwabe & ME McGlaughlin, “Genetic tools weed out misconceptions of strain reliability in Cannabis sativa: implications for a budding industry”, J Cann Res, 1 (2019). DOI: 10.1186/s42238-019-001-1
About the Author
Matthew Hallam

I've always wanted a career in which I could practice my creativity, even when I worked on the assembly line in a fish factory. At one time, I channeled this need into dance, drawing, poetry and fiction, and I still do most of these things. But, following completion of my MSc(Res) in Translational Oncology and time working in labs and as a Medical Writer for major pharmaceutical companies, I'm happy to find myself in a career that allows me to combine my creative side with my scientific mind as the Deputy Editor of The Analytical Scientist.

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