Since the 1970s, cannabis has been divided into three sub-species (often confused as different species), C. indica, C. sativa, C. ruderalis, with ruderalis largely being considered ‘wild cannabis,’ not fit for medicinal or recreational uses. A common lay-persons distinction is between marijuana, which is bred for high cannabinoid content, and hemp, which is bred for industrial uses like fiber.

Any of the three subspecies can be bred as a hemp or marijuana plant. John McPartland, a researcher affiliated with GW Pharmaceuticals, presented a study at the 2014 meeting of the International Cannabis Research Society, proposing a new nomenclature for cannabis. The original report on O’Shaughnessy’s contains more information than I can reproduce here, and has a wonderful chart; it is definitely worth your time to read.

It seems Richard Evans Schultes, the man who created the original taxonomy for cannabis in the 1970s, misidentified a C. afghanica plant as a C. indica plant. That one mistake began 40 years of confusion which has only been dispelled by McPartland’s research this year.

McPartland was the first researcher to look at the genetic markers on the three subspecies of cannabis using the plant’s genome to conclusively identify where it originated. He also proved conclusively that they are all the same species, just different subspecies. As it turns out, C. sativa should have been identified as C. indica, because it originated in India (hence indica). C. indica should have been identified as C. afghanica, because it actually originated in Afghanistan. Finally, it seems that C. ruderalis is actually what people mean when they refer to C. sativa.

If that sounds confusing, refer to this handy table, or the original chart.

Cannabis Indica (Formerly Sativa)

Origin: India

Morphology: Taller (>1.5m) than their short and stocky Afghanica cousins, with sparser branches and less dense buds/flowers.

Physiology: Longer flowering time, between nine and fourteen weeks. Minimal frost tolerance with a moderate production of resin.

Chemistry: Much greater THC than CBD and other cannabinoids, this leads to the “head high” many users report.

Psychoactivity: Stimulating.

Cannabis Afghanica (Formerly Indica)

Origin: Central Asia (Afghanistan, Turkestan, Pakistan)

Morphology: Shorter (<1.5m) than Indica strains with dense branches with wider leaves, and much denser buds/flowers

Physiology: Shorter flowering time, as little as seven to nine weeks. Good frost tolerance with high resin production. Afghanica strains can be susceptible to mold due to how dense the buds and branches are.

Chemistry: More variable than Indica strains. THC is often still the predominant cannabinoid but some strains have 1:1 ratios and some may have even higher CBD than THC.

Psychoactivity: Sedating.

Cannabis Sativa (Formerly Ruderalis)

Origin: Usually feral or wild. From Europe or Central Asia.

Morphology: Variable, depending on origin.

Physiology: The flowering time is short and variable, many varieties exhibit autoflowering traits (flowering independently of sun cycles). Moderate frost tolerance with relatively low resin production.

Chemistry: More CBD than THC. Prominent terpenes include caryophyllene and myrcene, giving these strains a floral flavor and scent.

Psychoactivity: Usually lacking.

This new nomenclature should come to replace the old system, because it is grounded in the actual genetics of the plant and is scientifically sound. Despite that, it is likely that this new naming scheme will face resistance from cannabis users and those in the medical cannabis industry who will have become used to decades of convention firmly establishing an inaccurate taxonomy.

This is reminiscent of the Brontosaurus, a dinosaur that never existed but we were all taught in school it was real, or the former 9th planet of Pluto (now a ‘dwarf planet’). Sometimes science gets it wrong and it is up to modern scientists with better methods, like McPartland, to correct our old mistakes.

The difficult part will be getting mass acceptance of his newly proposed taxonomy. What seems likely is that a split may develop between academics and laymen, with academics adopting the new system and laymen continuing to adhere to the old system, at least for a few more years.

Perhaps in time C. afghanica, C. indica, and C. sativa will come into the vogue, but that largely depends on the willingness of the medical cannabis industry to adopt this new system and thus pass it on to the patients and growers. But it seems unlikely that the cannabis industry would wholeheartedly jump on board, given the risk that this new nomenclature could confuse patients who may be used to seeing only “indicas” and “sativas” on the shelf.

Time will tell.