A cultivar is a group of cultivated plants that all share the same character or characters that are consistently inherited within the group. This means that the cultivar is defined by the phenotype, and not specifically by the genotype. In other words,
A cultivar is a sort of functional grouping of plants based upon the fact that they fit a certain criterion—the trait or traits the breeder was looking for in selecting the cultivar in the first place.
To come back to the classification debate I propose looking into this aspect of the plant as a way to categorize cultivars. In his article “Cannabis – From Cultivar to Chemovar,” Dr. Arno Hazekamp proposes that cannabis is a monotypic species of cannabis sativa however, there are more than 700 varieties within that species. By looking at over 26 combined cannabinoids and terpenes Dr. Hazekamp was able to accurately classify two different samples acquired from a coffee shop and compare them to several of the Dutch pharmaceutical cultivars. He concluded that using their chemical footprints he could accurately group the different samples together.
Another scientist in Europe, Etienne De Meijer from GW Pharmaceuticals in the UK, proposed five different cannabis types based on the relative content of three major cannabinoids (THCA, CBDA, CBGA). This, however, misses out on the terpenes, which as we know, have a modulating effect on the cannabinoids and are the components that largely dictate the direction of the effect. Without this key defining aspect of the plant, it would be impossible to accurately predict effects. By using these chemical fingerprints we could more accurately group plants into effect-based categories giving consumers a clearer picture of how they will experience their highs. We would still need to look at people’s individual DNA as that too effects how the cannabis they consume effects them, but at least this new form of classification would be a more accurate way to describe various subtypes rather the conventional sativa or indica or hybrid.
Another interesting additional means of classification will be to examine flavonoids. These pigment based molecules were shown in a ’70s thesis to accurately separate what back then would have been sativas from indicas. This thesis written by Murray Nelson Clark for his graduate degree from UBC found that the flavonoid luteolin was a clear marker for the long flowering thin-leaf drug varietals also known as a sativas. This paper was written in 1975 and the accessions he used or genetic samples were from plants that would have been as close to un-hybridized plant cultivars as existed back then. They included ruderalis samples, samples from South Africa and Cambodia and also ones from the University of Mississippi. In his tests, the plats that had a thin leaf morphology contained luteolin at a rate of 99.9 percent of the samples. This led him to conclude that this was a defining indicator of what they knew to be sativa-dominant plants at the time.
Strain Has No Accepted Meaning
What about the term “strain,” and where does it fit? The term strain appears to be used most often and most correctly in connection with microbes and viruses (think: flu strain), and more informally in reference to plants and rodents. In plants it has no official meaning but generally applies to the group of offspring that are descended from a modified plant.
The term is not often used to describe plants. It does sometimes show up in breeding, but mostly as it relates to genetic modification. If genes of a wheat plant are altered, the offspring of that modified plant might be deemed a strain.
Cannabis strain can be defined as a group of plants created asexually through clonal propagation. This is the most common form of plant production in the marijuana industry. Clones, by definition, are nearly identical genetically with the exception of the random mutations during plant cell division in the development of the “mother plant” (the plant from which a population of clones is generated). Mutations are almost always deleterious. A single mother plant creates a finite number of progeny so the maintenance of a strain requires cloning from the progeny of the original mother. Mutations accumulate with each successive generation so that, eventually, clone quality (e.g. cannabinoid profile.) deteriorates to the point that the strain is abandoned. Some may refer to this mutational load as genetic drift but this is a misnomer.
Cultivar is Most Correct, but Why?
Some plants, like Cannabis and turfgrasses, are propagated both via seeds and by cloning. For example, some Cannabis cultivars have traits that are uniform enough to be seed-propagated and other Cannabis cultivars require clonal propagation to maintain their key traits. This fact demonstrates why it was important to come up with a an inclusive term, like cultivar, that would cover both situations—cultivated varieties phenotypically “uniform enough” for commercial purposes, whether those varieties happened to be genotypically uniform or not. However the cultivation and selection is done, and whatever traits collectively are important enough to define the cultivated variety, that set of traits, uniformly inherited, defines the cultivar.
This usage appears much more common in Cannabis than in other plants I have worked with. My guess is that this is because Cannabis breeders have not been as involved in the out-in-the-open cultivar development and naming and intellectual-property protection process as breeders of other plants. So maybe it will take a while for the Cannabis community to move from “strain” to “cultivar,” or maybe it will remain a part of the idiom of the industry.