Figure 1S. Cannabis taxonomy: a problem throughout the history
Cannabis sativa L., with the onlyHumulus lupulus, belongs to Cannabaceae family. Over the centuries, the selection and cultivation have generated about 700 cultivars of this unique species that for a classification error is now referred to as C. sativa L., now as C. indica Lam. Indeed, the binomial C. indica and C. sativa has been maintained in pharmacological and toxicological literature, creating strong confusion. It is now clear that the only species of the genus Cannabis is characterized, according to the different content of psychoactive substances, in two subspecies: a species having greater value for fiber and oil (C. sativasubs. sativa) and one with greater inebriating potential (C. sativa subs. indica).The first to describe the plant was Linnaeus, who in 1753 considered the existence of the only species Cannabis sativa (Pollio 2016). The first disagreements came only thirty years later from Lamarck who determined that the strains of Cannabis coming from India are different from the European ones, thus calling the new species precisely C. indica Lam.The main distinguishing features of C. indica are a greater branching of the plant, a thinner bark, narrower leaves and the general ability to induce a state of intoxication if consumed.Further independent families of Cannabis were subsequently proposed, such as C. ruderalis Janisch, discovered by the Russian botanist D.E. Janischevsky during studies carried out on spontaneous varieties grown in central Russia.A further step forward made in understanding Cannabis botany is due to the research of another Russian botanist, Nikolai Ivanovich Vavilov, who considered the wild species C. ruderalis to be synonymous with C. sativa L. var. spontaneous Vav. and not an independent species, but rather a spontaneous variety of C. sativa. Moreover, the same Vavilov, after having discovered some wild populations in Afghanistan different by the spontaneous variety of C. indica, coins the new taxonomic genus of C. indica Lam. var. kafiristanica Vav. Small and Cronquist in more recent times have proposed the hypothesis of a single categorization for Cannabis, illustrated in the book "Practical and Natural Taxonomy for Cannabis". It was 1976. This new classification modified the previous concepts of Lamarck and Vavilov, grouping all the subspecies of the plant under the "mother species" C. sativa.The C. indicawas then redefined as C. sativa L. subsp. indica, subspecies of C. sativa and differentiated on the basis of the purpose of cultivation, used mainly for medicinal use and not for fibers and seeds. Small and Cronquist also forked both subspecies (indica and sativa) in 'wild' and 'domesticated' varieties based on seed size and other plant characteristics. Hillig (2005), based on genetic studies, demonstratedthat the genus Cannabis derived from distinct gene pools. Thus, the two species C. sativa and C. indica were again distinguished,and the third species C. ruderalisadded. Genotyping studies also showed that marijuana and hemp cultivars are significantly differentiable at gene level (Sawler et al. 2015). The taxonomic problem, which has lasted for more than two centuries, has been joined by the folk classifications according to which hemp plants can be selected for fiber, to obtain seeds for oil, for the production of plants with intoxicating power. Based on the phenotype, Cannabis plants are distinguished in drug-type (THC> 0.5%, CBD <0.5%), intermediate (THC = CBD), hemp fiber type (very low content in THC).
Hilling KW (2005) Genetic evidence for speciation in Cannabis (Cannabaceae). Genet Resour Crop Evol 52:161–180.
Pollio A (2016) The name of Cannabis: a short guide for nonbotanists. Cannabis Cannabinoid Res 1:234–238.
Sawler J, Stout JM, Gardner KM, Hudson D, Vidmar J, Butler L, Page JE, Myles S (2015) The genetic structure of marijuana and hemp. Plos One 10:e0133292.