Controversial taxonomy of hemp

Hemp (Cannabis sativa L.) was one of the earliest domesticated plant species. Biological classification (taxonomy or systematization) manifests evolutional relationships between taxons according to trait similarities. When it comes to taxonomy, hemp is one of the most controversial plant species due to significant effects of environmental conditions on hemp phenology and expression of quantitative traits as well as different levels of gender expression observed in hemp plants. Controversial taxonomy of hemp has gone through several phases throughout history. The attitude on the number of species within the genus Cannabis and the criteria used in taxonomic units division were under dispute. Initially focused on morphological characteristics and geographical origin, the approach was greatly amended by the development of molecular and biochemical techniques. The main cause of taxonomic uncertainties is the inbreeding ability of all wild Cannabis populations, resulting in continual variability of quantitative traits. The aim of the paper is to review the history of Cannabis classification including different approaches to this scientific issue.