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Advanced Cannabis Classification Gets a New Facelift with 16 Terpene Clusters

by | Nov 20, 2023

cannabis classification header image

Written by Jessica McKeil

Jessica McKeil is a cannabis writer and B2B content marketer living in British Columbia, Canada. Her focus on cannabis tech, scientific breakthroughs, and extraction has led to bylines with Cannabis & Tech Today, Terpenes and Testing, Analytical Cannabis, and Grow Mag among others. She is the owner and lead-writer of Sea to Sky Content, which provides content and strategy to the industry’s biggest brands.

Cannabis classification has eluded botanists, researchers, and breeders for centuries. Even with today’s genetic and advanced chemical analyses, the industry remains divided on what categories, if any, we can use to distinguish one type from another.

As stated by one team of researchers, cannabis’ “vernacular naming convention has become unreliable and inadequate for identifying or selecting strains for clinical research and medicinal production.” While there are many approaches to classifying cannabis, none work from the consumer’s perspective.

Could terpenes be the key to solving the cannabis classification puzzle once and for all? It’s an idea gaining traction, and not just among scientists. From Blueberries to Cookies to Kush, could we use clusters of terpenes to classify cultivars and ultimately facilitate a more predictable experience for consumers and patients alike?

After speaking with one of the leading voices in this field, Hubert Marceau, ​​Directeur de Développement at Laboratoire PhytoChemia in Quebec, Canada, it seems possible that the industry is on the cusp of a classification breakthrough.

The Long and Inexact History of Cannabis Classification 

vintage cannabis classification, vintage drawing.
It has taken scientists and botanists several centuries of work on cannabis classification, and we still aren’t there yet.

Cannabis has undergone several nomenclatural transformations since Swedish botanist Carl Linnaeus first attempted to categorize the species in the 18th century. Under Linnaeus’ declaration, the species was singular, locked in as Cannabis sativa.

But then, rather quickly, Jean-Baptiste Lamarck proposed two separate species of cannabis: Cannabis sativa and Cannabis indica. It was an attempt to account for the geographic and morphological differences between plants growing in the Indian subcontinent versus in North America. 

However, prominent botanists rejected this second species only a few decades later. Over the next century, cannabis classification didn’t get any clearer. Even as we rolled into the 1990s, a third type, Cannabis ruderalis, was proposed.

Despite several centuries of scientific debate, the incredible capabilities of modern-day genetics testing, and our advanced techniques for chemical analysis, the cannabis industry is only just (and barely) moving on from classifying all cannabis as indicas or sativas.

Beyond the dispensary shelves, there are countless ways cannabis is divided, subdivided, and classified. Scientists discuss drug-type vs non-drug-type while regulators work with marijuana vs. hemp, and if we want to go even further with a proposition from Ernest Smalls, there could be as many as six groups:

“Two composed of essentially non-narcotic fiber and oilseed cultivars as well as an additional group composed of their hybrids; and two composed of narcotic strains as well as an additional group composed of their hybrids.”

From the consumer perspective, none of these classifications provide accurate or reliable information on the end experience, which may be why the stereotypes of sativa and indica linger on product labels. It’s the closest, albeit wildly imperfect, means for consumers to customize their high. 

Consumers need something to navigate with, especially when presented with a never-ending list of options, thousands of strains, and endless possible psychoactive experiences. Thus far, a sleepy indica and an energizing sativa, or an in-between hybrid, are about as accurate as we have gotten.

A New Approach: Cannabis Classification by Terpene Profile

Over the last decade, many have proposed a more accurate cannabis classification system that will help recreational consumers better choose their adventure and medicinal consumers get better therapeutic outcomes.

Whether it’s the Emerald Cup teaming up with Phytofacts and SC Labs to create a new terpene classification system compromising six distinct families of aromatic profiles or the Vigil Index of Cannabis Chemovars (VICC) that relies on “a four-character chemovar code that broadly describes the primary and secondary terpene levels, as well as THC and CBD levels,” the 

industry is awash in proposals. 

Yet, they all generally have one thing in common: terpenes. In almost every case, the new strategy for cannabis classification hinges on the plant’s complex terpene fingerprint that gives each cultivar its unique aromatic profile. 

Terpene Clustering: What Evidence from 6500 Samples Tells Us

Hubert Marceau, ​​Directeur de Développement at Laboratoire PhytoChemia terpene cannabis classification graph
Image provided by Hubert Marceau, ​​Directeur de Développement at Laboratoire PhytoChemia

Hubert Marceau, ​​Directeur de Développement at Laboratoire PhytoChemia in Quebec, Canada, is adding evidence to the terpene consensus. His lab specializes in testing volatile botanical compounds from various sources, including cannabis. Marceau’s current obsession is to find novel ways to quantify and detect chemotypes in cannabis. 

The inspiration behind this article was actually from one of his more recent LinkedIn posts, where he previewed the preliminary results of his work categorizing cannabis cultivars by volatile profiles. 

While still in the early stages of this research, Marceau and his team have already found polymodal distribution within the 6,500 samples in their data analysis, unsurprisingly driven by terpenes. 

As Marceau explained, “By looking at these, we know that there are some variations going on in the cannabis plant. And we are able to say, ‘This fits with the label that was put there by the producer, the strain name.'” Essentially, this approach to classifying cannabis strains by volatile chemical families is a template for better data analysis and, for consumers, better prediction of strain effects.

Marceau underscored that his work is still in the early stages and that many of the parameters they’ve played with have been arbitrary thus far. Still, from these samples, the Marceaus team tested different methodologies pulled from the literature and their own previous research. 

Unlike other research published on this topic, Marceau’s team didn’t start with labels, just the data from the samples. As he detailed in our interview, they didn’t “give bias to the system based on what could be wrong labeling.” 

As soon as they started graphing the data points, Marceau’s team began to “clearly see clusters appearing” in the terpene distribution. Already, they’ve found 16 broad clusters (although Marceau admits it could easily have been 700, but this is unrealistic for a consumer-driven industry). 

One cluster may be created from mostly cookie-type strains, while another from kush-types. Again, because Marceau and his team only look at strain names afterward, any inaccurate names don’t impact the original cluster formation. They are now working on identifying the main contributors within each of these groupings or families. 

Interestingly, some of these clusters seem to correlate with previous research working on this cannabis classification approach, which leads Marceau to postulate that there may be a “finite number of clusters, or an optimal amount of clusters, because the data seems to converge in this direction.” 

Embracing Terpenes for Accurate and Concise Cannabis Classification

If we are ever to move beyond the inexact cannabis classification of indica and sativa, we need to follow the data. The quest for a definitive cannabis classification system remains critical for everyone from regulators to consumers to healthcare professionals. 

The historical approaches, ranging from the simplistic indica-sativa dichotomy to complex botanical categorizations, have proven inadequate for addressing the diverse needs of our industry. What’s emerging now, as highlighted by Hubert Marceau’s research, is a promising new paradigm: classification based on terpene profiles.

As it adds to the growing literature, the significance of Marceau’s work cannot be understated. It represents a shift toward a more scientifically grounded yet still consumer-friendly cannabis classification system. This method not only aids consumers in making informed choices but also paves the way for more targeted and effective medicinal use of cannabis. 

Already, as Marceau has mentioned, there seem to be convergences in terpene clusters. And while the path to a comprehensive and universally accepted cannabis classification system is undoubtedly a long one, the goal is within sight. The future of cannabis classification, therefore, lies not in the oversimplified labels of the past but in the rich and varied tapestry of terpenes that define each unique strain.

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