Comprehending cannabis strains is a complex and rather contentious topic, complicated by vast differences in common vernacular and scientific plant classification, known as botanical nomenclature. As with most things in society, the language we use surrounding cannabis- both medical cannabis and recreational cannabis – informs the actions of individuals, industry and cultural beliefs. Many researchers and industry thought leaders believe the confusion surrounding cannabis strains and the resulting variability in products is a detriment to the integrity of the industry and patient outcomes.
Historically there has always been confusion surrounding methods for classifying plants, until Carl Linnaeus formalised naming conventions in the 18th Century, different regions utilised different approaches. Over time many Latin binomials for plants that denote their genus and species (eg. Cannabis sativa) have been reclassified or renamed as botanists gain a deeper understanding of their phytochemical and genetic profile – further fueling confusion.
The story of strains entwines with that of species, so let’s start there given species rank higher in taxonomy. In the case of cannabis, even after years of research, the consensus on species within the cannabis genus is still expressed differently by various botanists and cannabis researchers.
Some prescribe to the theory that all cannabis- both medical cannabis and recreational cannabis – derives from the Cannabis sativa species. The concept that all other species (indica, ruderalis) are subspecies of Cannabis sativa was proposed in 1976 by Earnest Small and Arthur Conquist and is now the generally accepted convention.
Within this, Cannabis sativa is classified as the sole species, with subspecies further divided as follows:
While many in the scientific and botanical community prescribe to this method, there are others, such as cannabis botanist Robert Connell Clarke, that still believe the indica/sativa species paradigm to be accurate.
Prominent cannabinoid researcher Ethan Russo believes the common vernacular describing denoting indica/sativa is “total nonsense and an exercise in futility”, he encourages the medical cannabis scientific community and the wider public to abandon the indica/sativa paradigm for detailed understanding of phytochemical profiles.
Moving now from species to strains, there is no scientific convention for naming cannabis strains, nor is there a taxonomical rank within botanical nomenclature. Without diving too much further into plant taxonomy, comparable instances with plants that might be called ‘strains’ in the medical cannabis and ault-use landscape, would be classified as varieties.
For instance, tomatoes come under the binomial Solanum lycopersicum, yet it is the varieties that give us a range of different tomatoes ie. Roma or Black Russian tomatoes.
So it has been through human design, plants have been hybridised and bred for specific cannabinoid profiles or growing conditions, creating cultivated varieties or cultivars. Thus cannabis strains are more accurately scientifically labelled by the interchangeable terms of cultivar or variety.
Resources like the Phylos Galaxy give good visual examples of how many varieties there are available and how they are genetically connected.
Image: Phylos Biosciences
Landraces is another term that is commonly encountered when fleshing out an understanding of cannabis strains.
Landraces are varieties originating from (or having been introduced to) a certain region where it has grown for an extended period of time, a couple of centuries at the very least. This results in strong genetics leading to predictable growth patterns, appearance, THC, CBD oil and phytochemical composition.
Having grown and adapted to specific climatic and environmental conditions for so long, landrace varieties are generally robust enough to produce homogenous offspring – for example, seeds that are likely to produce medicinal cannabis plants with very similar characteristics and genetics to the parent.
Landraces are essentially the ancestors of modern varieties, both those bred from adult-use and those meticulously cultivated for medicinal cannabis formulations. Yet due to extensive hybridisation original landrace varieties are hard to come by.
A chemovar describes a group of cannabis ‘strains’ or varieties that exhibit similar phytochemical profiles and are thus grouped together. When we take into account the vast amount of hybridisation, as well as the fact that cannabis seeds are not direct genetic replicas for the mother plant, grouping cannabis in terms of chemovars makes sense.
Broadly chemovars are grouped as noted below, with further testing done determining minor cannabinoids, terpenes, flavonoids and other phytochemicals.
By understanding the THC:CBD oil ratio and phytochemical profile of varieties, medical cannabis prescribers can gain a greater understanding of which chemovars are best suited to specific medical conditions.
Cannabis industry adopted the term strain from microbiology, where different bacteria, viruses and fungi manifest from the same species or subspecies, yet with a slightly different genetic code creating strains.
The continued use is largely to do with the human tendency to use familiar concepts for ease of understanding. The public is cognisant with the terms sativa, indica and strains. Familiarity reduces decision-making fatigue, so by being able to make broad assumptions about the action of a plant by its strain consumers may find it easier to choose.
Strain names also offer a marketing tool for companies operating in both recreational and medical cannabis markets. Unfortunately, in an already stigmatised industry, pop-culture-inspired strain names do little to bolster confidence in the medicinal cannabis aspects of the plant.
Asides from cannabis strain names being redundant in terms of scientific classification, they aren’t reflective of an evidenced-based understanding of a particular variety. While the terms cultivar or variety are a more scientifically accurate description than ‘strain’, it is still challenging to account for the many variabilities that come with cultivating cannabis. Which brings us to genetics…
You can’t discuss cannabis varieties or cultivars without at least touching on the complexities of genetics. There are two key factors that determine the physical and phytochemical manifestations in a plant these are; the genetics innate to the plant or seed and the external factors that influence the expression of genetic traits. Referred to as the genotype and phenotype, respectively.
Whilst cannabis seeds produced from the same mother plant may have a very similar genotype -think fraternal twins, not identical ones- it is the environment (water, light, altitude, etc) that activates the expression of these genes, giving rise to the phenotype. Thus cannabis seeds with the similar genotype can exhibit a different phenotype and therefore cannabinoid profile to the mother or sibling plants.
This places a lot of pressure on medical cannabis companies to create homogenous cannabis plants, where THC, CBD oil and terpene profiles are within a specific range, to ensure consistency and quality in the resulting raw material.
Fortunately, with cloning and other modern cultivation techniques, as well as diverse extraction and formulation methods, the medical cannabis industry has found ways to ensure patients are receiving extensively tested and standardised products.
What is more relevant to the application of medical cannabis is not the strain name but the phytochemical profile. Different cannabis varieties contain varying levels of cannabinoids (like CBD oil and THC), terpenes, flavanoids and numerous other phytochemicals, it is the ratio of these constituents and their synergistic actions that determines specific therapeutic effects.
Discerning the chemical profile of a cannabis variety can be done via a number of methods. High performance liquid chromatography (HPLC) is the most commonly utilized method to determine cannabinoid levels. Gas chromatography or mass spectrometry (GC or MS) are two other ways used to measure terpene and phytochemical content.
More recently scientists have been experimenting with RNA testing. While this method may not be suited to testing mass raw cannabis, it does provide an understanding of the RNA and gene expression that allows for more accurate differentiation between cannabis cultivars.
As scientists gain deeper understanding of the actions of cannabis phytochemicals and their effect on the Endocannabinoid System, physicians will be able to have greater confidence in prescribing medical cannabis products with a focus on specific constituents for individual conditions.
Despite recreational, and illegal cannabis markets continuing to fuel the strain and indica/sativa paradigm, the medical cannabis community continues to push for a more scientific and evidence-based approach. What is more important than the strain is the composition, quality and consistency of a medicinal cannabis.
All doctors who prescribe medical cannabis in the UK will typically focus on the specific chemical content that will be best for each patient. ‘Indica does x, and sativa does y’ is a significant oversimplification, when in reality the prescribing doctor’s decision is much more complicated.
Having confidence that a medical cannabis flos/flower, or oil/tincture has a specific THC:CBD oil ratio and phytochemical profile, is free from contaminants, is standardised and of pharmaceutical-grade quality ensures that patients receive safe and repeatable medication.
By steering away from pop-culture inspired strain names and focusing on cannabinoids and phytochemicals, there is a greater opportunity to effectively treat conditions and foster a destigmatised and evidenced-based medical cannabis industry.
By Jessica Kindynis
Whilst researchers continue to focus their efforts into new ways of combating COVID-19, a number of researchers are looking into whether cannabis or cannabis derived CBD (cannabidiol) or THC (tetrahydrocannabinol) might offer support for those suffering from severe forms of this infection.
ElSohly, M., Radwan, M., Gul, W., Chandra, S., & Galal, A. (2017). Phytochemistry of Cannabis sativa L. Progress In The Chemistry Of Organic Natural Products, 1-36.
Piomelli, D., & Russo, E. (2016). The Cannabis sativa Versus Cannabis indica Debate: An Interview with Ethan Russo, MD. Cannabis And Cannabinoid Research, 1(1), 44-46.
Pollio, A. (2016). The Name of Cannabis: A Short Guide for Nonbotanists. Cannabis And Cannabinoid Research, 1(1), 234-238.
Reimann-Philipp, U., Speck, M., Orser, C., Johnson, S., Hilyard, A., & Turner, H. et al. (2019). Cannabis Chemovar Nomenclature Misrepresents Chemical and Genetic Diversity; Survey of Variations in Chemical Profiles and Genetic Markers in Nevada Medical Cannabis Samples. Cannabis And Cannabinoid Research.
Small, E., & Cronquist, A. (1976). A practical and natural taxonomy for cannabis. Taxon, 25(4), 405-435.
Zager, J., Lange, I., Srividya, N., Smith, A., & Lange, B. (2019). Gene Networks Underlying Cannabinoid and Terpenoid Accumulation in Cannabis. Plant Physiology, 180(4), 1877-1897.