Cannabis sativa vs. Cannabis indica

• Vernacular taxonomy
• Botanical taxonomy
• Chemotaxonomy
• Taxonomy based on genetic sequencing
• Summary, tables, illustrations

As we mentioned in the Varieties chapter, there are numerous characteristics by which cannabis plants can be classified, and different types of taxonomy are used for that matter. In this chapter, we will explain the most common ones.

Vernacular taxonomy

A vernacular taxonomy (or more accurately, a nomenclature of sativa and indica) has developed among recreational growers and users of cannabis.¹ They often refer to cannabis varieties as ‘strains’. Recreational users and medical patients use this system because it is based on the reported – although not scientifically verified – physical effects that the strains exhibit. According to this common and unsubstantiated belief, the effects by sativa ‘strains’ are described as uplifting and energetic, and are considered more hallucinogenic. In contrast, indica ‘strains’, including hybrids (a cross-breed between the two varieties), are described as calming and are said to cause relaxation and stress relief.² However, a medical doctor and researcher John McPartland wrote:

”Categorizing cannabis as either “Sativa” and “Indica” has become an exercise in futility. Ubiquitous interbreeding and hybridization renders their distinction meaningless. The arbitrariness of these designations is illustrated by “AK-47,” a hybrid that won “Best Sativa” in the 1999 Cannabis Cup, and won “Best Indica” four years later.”³

Botanical taxonomy

Botanically (i.e. from the plant-science perspective), cannabis has been sub-classified based on its phenotypic traits {call-out, text:The observable properties of an organism that are produced by the interaction of the genes and the environment.} to distinguish the differences between sativa and indica cultivars. Both cultivars are subspecies of Cannabis sativa L.⁴ Sativa cultivars are phenotypically characterized as being tall with a fibrous stalk, widely spaced branches, and long thin leaves; they were originally cultivated for the industrial use of fiber, seed oil, and animal feed. In contrast, indica cultivars, originally from Southern Asia, are characterized as shorter bushy plants with a woody stalk and broader leaves that are known to be psychoactive.^{1, 3} Due to extensive breeding programs, most of the cannabis used medically is a hybrid of sativa and indica cultivars. Some researchers recognize a third cultivar: cannabis ruderalis, a smaller, weedy plant originally from Central Russia (see Figure 1).⁴

Chemotaxonomy

If you want to study effects of different cannabis varieties, it makes sense to classify cannabis varieties based on their chemical profile, called chemotaxonomy – the chemical constituents are largely responsible for the effects that are induced in the body. Chemotaxonomy is a field that is still under development and has changed a lot, especially over the past decade. In earlier stages of chemotaxonomy, several scientific groups made a joint effort to classify cannabis varieties into 3 chemotypes: a high THC, a high CBD, and a variety with comparable levels of THC and CBD.⁵ This classification method could be applied to some degree for the purpose of effect prediction, however, it is generally ineffective in distinguishing between botanical cultivars. Other groups were also not able to distinguish between vernacular sativa and indica types. For example, Elzinga and colleagues performed a principal component analysis {call-out, text:An analysis used to accentuate differences and highlight patterns in a dataset.} of 31 chemical compounds in 494 flower samples (35 varieties). They concluded that variability and overlapping were too great to differentiate between indica and sativa varieties based on the cannabinoids and terpenes.⁶ To some extent, they were able to identify groups of varieties that clustered together.⁶ For example, the group of varieties named ‘Harlequin’ consistently contained more CBD than other varieties tested in this study. Lynch and colleagues found some chemical differences between the two varieties, but focused on the botanic taxonomy rather than the vernacular: broad leaf type plants (botanically referring to indica) had a significant different percentage of the terpene linalool, compared to narrow leaf plants (botanically referring to sativa) and hemp-type plants. The terpene terpinolene was different in the narrow leaf type.⁷ Furthermore, while higher CBD concentrations are typically associated with cannabis indica at cannabis retail locations,  this study found that the broad leaf type had less CBD than the narrow leaf type.⁷ Metabolic taxonomy is a type of chemotaxonomy brought up by another group of researchers who combined the chemical composition with vernacular information, thereby providing a unique chemical fingerprint.⁸ A classification system of chemovars was proposed to differentiate cannabis chemical varieties. ⁸ Researchers tested 460 cannabis samples for 44 cannabinoids and terpenes simultaneously, thereby using multivariate data analysis {call-out, text:Involving several independent mathematical or statistical variables\, and an analysis of more than one statistical outcome variable at a time.} to determine each sample’s unique signature. As far as vernacular indica versus sativa types, they were able to separate the two based on total chemical composition, specifically their different terpene content (see Table 2).⁸ Contrary to popular belief, there was no difference in the major cannabinoids, THC and CBD, but they observed that cannabichromene (CBC) and cannabigerol (CBG) were more pronounced in sativa type, while the mean THC concentrations were similar.⁸ Also, they noted that the so-called hydroxylated terpenes were more prevalent in indica than sativa.⁸ This work was built on their earlier work⁹ in which they showed a difference in their terpene profiles in two recreational varieties, a sativa-dominant (Amnesia) and an indica-dominant (White Widow). Dominant refers to cross-bred plants that predominantly consist of one variety. They also found that two out of three pharmaceutical-grade cannabis samples, namely Bedica and Bedrobinol, more closely matched the indica-dominant variety (White Widow), even though Bedrobinol is derived from a sativa-dominant variety (a Haze variety). The third pharmaceutical-grade cannabis sample, Bedrocan, was actually distinctly different in its terpene profile from both sativa-dominant and indica-dominant clusters.⁹

Taxonomy based on genetic sequencing

There is also a growing interest in classifying strains based on their genetics. Van Bakel and coworkers reported the draft genome of cannabis.¹⁰ The sequenced genome of several cannabis strains is available on the internet by several companies through Google’s BigQuery genomics cannabis dataset. Sawler and colleagues used the genetic sequence of cannabis to differentiate marijuana and hemp types of cannabis. This research concluded that cannabis sativa and cannabis indica were not genetically different. Also, there was no distinction between the varieties based on so-called single nucleotide polymorphisms (SNPs), a particular genetic variation.¹¹ Notably, they found cases where the genetic data strongly disagrees with the “reported” ancestry: they provided an example of a variety called ‘Jamaican Lambs Bread’ that was reported as 100% sativa, which turned out to be almost identical with a 100% indica strain from Afghanistan.¹¹ The researchers found that in 6 out of 17 comparisons (35%) between varieties at the genetic level vs. varieties with identical names, samples were more genetically similar to samples with different names than to samples with identical names.¹¹ This reinforces the fact that the name of a cannabis variety is not a reliable indication of the genetics of that variety.

Summary, tables, illustrations

Although generally outmoded, it is difficult to change the terminology that is commonly used by cannabis retailers and manufacturers and with which people got so familiar (cannabis sativa and cannabis indica). However, realizing that more research needs to be done to improve classification methods helps in understanding the general disappointment of many patients who find it hard to achieve consistent and desired effects. To fill the gaps in cannabis classification knowledge, studies on botanical taxonomy, chemotaxonomy, metabolic taxonomy, and taxonomy based on genetic sequencing are still being performed. Table 1: Botanical Differences Between Sativa, Indica and Ruderalis.

Botanical Differences Between Sativa, Indica and Ruderalis
Sativa	Indica	Ruderalis
Tall plant	Short plant	Small plant
Long thin leaves	Broad leaves	Smaller leaves
Widely spaced branches	Bushier plant	Weedy, less dense

Figure 1: The difference in plant size and leaf shape is evident in three cannabis cultivars (Image taken from Wikimedia). Table 2: Hazekamp and colleagues found that the terpenes listed in the table were strongly associated with their respective cannabis variety of indica or sativa.⁸

Association of Terpenes in Indica vs Sativa Types
Indica	Sativa
beta-eudesmol	trans-bergamotene
gamma-eudesmol	trans-beta-farnesene
guaiol	delta-3-carene
myrcene	terpinolene
gamma-elemene

References:

1. Upton, Roy; Craker, Lyle; ElSohly, Mahmoud; Romm, Aviva; Russo, Ethan; Sexton, Michelle (2013). Cannabis inflorescence : cannabis spp. ; standards of identity, analysis, and quality control (61). American Herbal Pharmacopoeia.
2. Pearce, Daniel D.; Mitsouras, Katherine; Irizarry, Kristopher J. (2014). Discriminating the Effects of Cannabis sativa and Cannabis indica: A Web Survey of Medical Cannabis Users. The Journal of Alternative and Complementary Medicine, 20(10), 787--791.
3. McPartland, John M. (2018). Cannabis Systematics at the Levels of Family, Genus, and Species. Cannabis and Cannabinoid Research, 3(1), 203--212.
4. Erkelens, Jacob L.; Hazekamp, Arno (2014). That which we call Indica, by any other name would smell as sweet. Cannabinoids, 9(1), 9.
5. Fischedick, Justin Thomas; Hazekamp, Arno; Erkelens, Tjalling; Choi, Young Hae; Verpoorte, Rob (2010). Metabolic fingerprinting of Cannabis sativa L., cannabinoids and terpenoids for chemotaxonomic and drug standardization purposes. Phytochemistry, 71(17-18), 2058--2073.
6. Elzinga, S.; Fischedick, J. (2015). Cannabinoids and Terpenes as Chemotaxonomic Markers in Cannabis. Natural Products Chemistry & Research. OMICS International.,.
7. Lynch, Ryan C.; Vergara, Daniela; Tittes, Silas; White, Kristin; Schwartz, C. J.; Gibbs, Matthew J.; Ruthenburg, Travis C.; DeCesare, Kymron; Land, Donald P.; Kane, Nolan C. (2016). Genomic and Chemical Diversity in Cannabis. Critical Reviews in Plant Sciences, 35(5-6), 349--363.
8. Hazekamp, Arno; Tejkalová, Katerina; Papadimitriou, Stelios (2016). Cannabis: From Cultivar to Chemovar II—A Metabolomics Approach to Cannabis Classification. Cannabis and Cannabinoid Research, 1(1), 202--215.
9. Hazekamp, A.; Fischedick, J. T. (2012). Cannabis - from cultivar to chemovar. Drug Testing and Analysis, 4(7-8), 660--667.
10. van Bakel, Harm; Stout, Jake M.; Cote, Atina G.; Tallon, Carling M.; Sharpe, Andrew G.; Hughes, Timothy R.; Page, Jonathan E. (2011). The draft genome and transcriptome of Cannabis sativa. Genome Biology, 12(10), R102.
11. Sawler, Jason; Stout, Jake M.; Gardner, Kyle M.; Hudson, Darryl; Vidmar, John; Butler, Laura; Page, Jonathan E.; Myles, Sean (2015). The Genetic Structure of Marijuana and Hemp. PLOS ONE, 10(8), e0133292.