Genomics-based taxonomy to clarify cannabis classification

Abstract

In the 18th century, Carolus Linnaeus created a formalized system of classification of living organisms based on their anatomic relationships, which we know as taxonomic nomenclature. Historically, the genus <i>Cannabis</i> has been described three ways under this system: <i>Cannabis sativa</i> by C. Linnaeus in 1753, <i>Cannabis indica</i> by J.B. Lamarck in 1785, and <i>Cannabis ruderalis</i> by D.E. Janischewsky in 1924, with these taxonomic classifications having been derived from physical, morphological, chemical, and geographical data. Today, this confusing taxonomy has led to an ongoing debate about whether the genus <i>Cannabis</i> consists of a single species or multiple distinct species or subspecies. Recently, genome sequencing and bioinformatics have provided greater resolution of taxonomic assignments at the species level. As a result, some previously discussed classification frameworks have been brought into question. The aim of this review is to provide a historical context for the confusion surrounding the taxonomy of the genus <i>Cannabis</i> and highlight recent research on genomics-based taxonomical approaches to clarify the question of <i>Cannabis</i> taxonomy. We suggest that the latest evidence shifts away from the previous multiple species framework and points towards the genus <i>Cannabis</i> consisting of a highly diverse monotypic species.