Taxonomy: botanical aspects

Classification of Cannabis Species Plantarum, published in 1753, was the first formal publication to document the usage of Latin binomials, genus and species names. Later, the international community recognised it as the foundation for contemporary botanical nomenclature. Cannabis means "cane-like," and the genus name "sativa" means "planted or sown," indicating that the plant is grown from seed rather than perennial roots (Raman, 1998). Cannabis is classified under the Cannabaceae family, along with the Humulus genus (hops) (Turner et al., 1980). Over many generations, different kinds of Cannabis have evolved as a result of breeding and selection.

Hemp plant is botanically and most currently classified as Cannabis sativa. This identification considers all strains, including hemp and marijuana, as one species, Cannabis sativa, as originally named by Carl Linnaeus.

The complete taxonomically classification is as follows:

●       Kingdom: Plantae

●       Order: Rosales

●       Family: Cannabaceae

●       Genus: Cannabis

●       Species: sativa

However, the taxonomic classification of Cannabis has been debated among botanists due to possible differences in origin and chemical composition. Nevertheless, while there are many strains with unique characteristics, they all are capable of interbreeding, and therefore do not meet the typical biological definition of species.

Other recent taxonomic studies have been focusing on quantitative criteria, such as chemotaxonomic classification. These criteria distinguish phenotypes based on quantitative differences in the cannabinoid ratios of tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN), expressed as [THC] + [CBN]/[CBD]. If the ratio exceeds one, plants are designated as "chemo-type," otherwise as "fibre-type," and Fetterman et al. (1971) conducted the first quantitative analysis to distinguish between the psychoactive and fibre-types. As a result, Turner et al. (1979) used this ratio to distinguish between chemotype, intermediate type, and fibre type. Furthermore, it has been stated that the Cannabis plant can be divided into several morphotypes based on its age and stage of development. Although this chemotaxonomic categorisation is insufficient to clarify infrageneric taxonomic structure and does not specify the cannabinoid content of each chemotype, it is a useful classification tool (Hazekamp et al., 2010).

Hemp is classified by statute in many states and countries where hemp can be legally produced as C. sativa plants with THC levels less than 0.3% on a dry-weight basis. Hemp has traditionally been farmed for textile and seed production. It contains low amounts of the psychoactive component delta-9-tetrahydrocannabinol (THC) and significant amounts of cannabidiol (CBD), a non-psychoactive molecule with potential therapeutic use.

However, industrial hemp does not fit into any agreed-upon taxonomic or evolutionary categorisation, but rather reflects a specific cannabinoid profile, particularly in terms of THC level, and the related legislative restrictions. The above-mentioned conventional definition of industrial hemp remains pragmatic, with no recognised taxonomic or phylogenetic classification. Instead, it represents a distinct cannabinoids profile, particularly THC concentration and the corresponding legislative limits.

Schultes, Klein, Plowman, and Lockwood (1974) identified three species in the genus: C. sativa L., C. indica Lam., and C. ruderalis. Small and Cronquist (1976) classified the same species C. sativa into two subspecies: sativa and indica, each with domesticated and wild variations. Other writers used the same taxonomic classification exclusively at the subspecific level of a single species, C. sativa (Hoffmann, 1961).

The United Nations Office on Drugs and Crime (UNODC) considers the designation C. sativa L. suitable for all plants of the genus, due to the difficulty of distinguishing the Cannabis sativa L. subspecies, either chemically or morphologically, and the fact that this genus exhibits continuous changes depending on the environment and conditions in which it is planted. Other species in the genus (C. sativa ssp. sativa, C. sativa ssp. indica, C. sativa ssp. ruderalis, C. sativa ssp. spontanea, and C. sativa ssp. kafiristanca) are all recognised as subspecies of C. sativa L. (UNODC, 2022).