Research conducted by members of the University of British Columbia and Dalhousie University in Canada has allowed scientists to paint a clearer picture of the evolutionary history and genetic organisation of cannabis.
Jonathan Page, a University of British Columbia botanist who co-led the first large scale study, published in PLOS One, of the genetic diversity of cannabis, said: "Even though hemp and marijuana are important crops, knowledge about cannabis is lacking because of its status as a controlled drug."
Page and Sean Myles, a population geneticist at Dalhousie University, researched the genotypes of 81 marijuana and 43 hemp samples and after using the DNA variants in the cannabis genome, they were able to search for the relationships between the different plants. There are three species of cannabis plants - C. sativa, C. indica and C. ruderalis – and the research has led scientists to the conclusion that all three are often mislabelled by growers.
Traditionally, marijuana plants have different characteristics. Indica-type plants provokes a relaxing state with sedative effects whereas Sativa-type plants are more stimulating, for example. However, the researchers found that there is only a moderate correlation between the ancestry of marijuana strains which is noted by breeders and the ancestry information gathered from their DNA. It says that, for example, a sample of Jamaican Lambs Bread is a strain of C. sativa, which is almost identical genetically to a C. indica strain from Afghanistan.
"Cannabis breeders and growers often indicate the percentage of Sativa or Indica in a cannabis strain, but they are not very accurate," Page said. "The genetic difference between marijuana and hemp has legal implications in many countries. Right now, the genetic identity of a marijuana strain cannot be accurately determined by its name or reported ancestry. Ultimately we require a practical, accurate and more reliable classification system of this plant."