As cannabis continues on the road toward normalization, many challenges still present themselves. One is the proper categorization and quantification of cannabis plants at the genetic and chemical levels.
Current Labeling Practices
Cannabis professionals and many in the mainstream use the terms sativa and indica when referring to different types of plants. They use these terms in reference to a plant’s certain characteristics, including the plant’s scents and the psychoactive effects it has on consumers.
However, the authors of a recent study argue that these two terms, sativa and indica, are unhelpful in conveying any meaningful information regarding the genetic and chemical profiles of cannabis plants. In fact, with specific reference to cannabinoids, researchers found that there was no distinct difference at a genomic level between the two different types of plants as categorized by current labeling practices. 
The research team analyzed nearly 300 THC-containing cannabis plants genetically using a five-point labeling scale. At no time did the terms sativa and indica, as used today, accurately express any real genomic, important distinction. Instead, the researchers found that the use of these terms is currently controlled by the psychoactive effects of a particular plant and the expression of its aroma-creating terpenes, which are governed by the genetic variation of terpene synthase genes and not the genetic variation of cannabinoids. 
What this all means is the terms sativa and indica are very limiting in what they actually describe. They do not offer any insight into the genetic differences between cultivars at the cannabinoid level, but instead only apply to a limited subset of characteristics based on terpene aroma and plant psychoactivity. Clarifying and establishing terms and categories of classification are essential for a healthy development of the cannabis market. With more research and dissemination of information, the researchers hope for more precise and comprehensive labeling practices in the future.
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Watts, S, et al. Cannabis labeling is associated with genetic variation in terpene synthase genes. Nature Plants. Vol 7(10), 1330-1334