Friday, February 5, 2016
Cannabis sativa vs. Cannabis indica: Science or Folklore?
Golden Goat or Sour Diesel?
Ethan Russo, a neurologist and pharmacology researcher, as well as the medical director of a biotechnology company, author of numerous books about herbal medicine, and a former faculty member at the University of Washington and the University of Montana, has something to say to marijuana connoisseurs: “There are biochemically distinct strains of Cannabis, but the sativa/indica distinction as commonly applied in the lay literature is total nonsense and an exercise in futility.”
How’s that again? The much-vaunted divide between the cerebral sativa strains, and the sedating, body-oriented effects of indica, are an integral part of marijuana lore and legend. Cannabis growers and biologists endlessly debate the hybridization of new strains. Extolling the virtues of a sativa plant crossed with a plant redolent of indica is a common sales pitch.
In an interview with Dr. Daniele Piomelli for the January 2016 issue of the journal Cannabis and Cannabinoid Research, Russo detailed his disagreement with the assumption that hard evidence exists for this distinction. Dr. Piomelli notes that “sativa is often described as being uplifting and energetic, whereas indica as being relaxing and calming.” Folklore, says Russo. Of course different strains have different effects. But in recent years, says Russo, almost all marijuana has been coming from high-THC strains, with a slight increase in CBD-predominant strains:
"The differences in observed effects in Cannabis are due to their terpenoid content, which is rarely assayed, let alone reported to potential consumers. The sedation of the so-called indica strains is falsely attributed to CBD content when, in fact, CBD is stimulating in low and moderate doses. Rather, sedation in most common Cannabis strains is attributable to their myrcene content, a monoterpene with a strongly sedative couch-lock effect that resembles a narcotic."
And, as for sativa strains: “A high limonene content (common to citrus peels) will be uplifting on mood, while the presence of the relatively rare terpene in Cannabis, alpha-pinene, can effectively reduce or eliminate the short-term memory impairment classically induced by THC.”
Well. I for one do not wish to be caught in the firing line between Dr. Russo and the legions of growers who will beg to differ with his conclusions. For years, it has been accepted wisdom that cannabis comes in two different forms, essentially considered two different species even though they readily interbreed. Even Jean-Baptiste Lamarck, the legendary naturalist of the 18th Century, agreed with the indica and sativa concepts.
But Russo will have none of it: “To paraphrase and expropriate an old Yiddish expression: 12 botanical taxonomists, 25 different opinions…. One cannot in any way currently guess the biochemical content of a given Cannabis plant based on its height, branching, or leaf morphology. The degree of interbreeding/hybridization is such that only a biochemical assay tells a potential consumer or scientist what is really in the plant.”
And finally: “I would strongly encourage the scientific community, the press, and the public to abandon the sativa/indica nomenclature and rather insist that accurate biochemical assays on cannabinoid and terpenoid profiles be available for cannabis in both the medical and recreational markets. Scientific accuracy and the public health demand no less than this.”
Russo’s interview is strong evidence of a viewpoint brought to public attention a few years ago by several others, including the controversial cannabis chemist Jeffrey Raber.
Raber told the L.A. Weekly in 2013 that there was no compelling scientific evidence for the claims routinely made by cannabis dispensaries about the effects of a given colorfully named strain of marijuana. “We took a popular [strain] name, Jack Herer, and found that most didn’t even look like each other. OG whatever, Kush whatever, and the marketing that goes along with it—it’s not really medically designed.”
And the difference between sativa and indica? The cerebral, bracing “mental” high vs. the sleepy, couch-lock “body” high? Forget it, said Raber. The two sub-species are distinguished by morphology only—different structures and appearance, but no hard and fast rules about the quality of the smoking experience. They look different, but that’s no guide to the distribution of THC, CBD, and numerous terpenes that determine the actual quality of the marijuana experience. Moreover, extensive crossbreeding by growers and dealers has helped to obliterate any consistent, meaningful distinctions between sativa and indica highs. (The so-called “skunk” varieties are simply high quality female plants that are prevented from going to seed, which dramatically pushes up the THC content. Almost all of the high-quality weed sold in the U.S., Canada, and the U.K. is skunkweed, so the definition is virtually useless.)
Sativa plants are characteristically tall and rangy, with long branches and long, thin leaves. They evolved, scientists believe, in humid jungle climates. Indica plants are shorter, more compact, and stubbier-looking, with shorter branches and fatter leaves designed for a hot, desert-like climate. It has been assumed that sativas originally came from India, and indicas from Afghanistan. However, indica is the term meant to indicate a plant from India, so right away we find that the situation is all muddled up: the plant from Afghanistan is known by the name of the plant from India. Blame this one on esteemed plant drug investigator Richard Evans Schultes, who apparently mislabeled the plants grown in Afghanistan as C. indica when he drew up the first cannabis taxonomy in the 1970s.
It gets worse. In 2014, at a meeting of the International Cannabis Research Society, research John McPartland with GW Pharmaceuticals announced the results of his study of genetic markers on the three subspecies of cannabis: C. sativa, C. indica, and a third wild variety, known as C. ruderalis, with very little THC. Any of the three subspecies can be bred as hemp or marijuana, said McPartland. Cannabis sativa should really be known as Cannabis indica, being the Indian variety, while the formerly misnamed indica subspecies should now be called Cannabis afghanica. The name of C. sativa, the high-end connoisseur favorite, would now go to the lowly C. ruderalis, otherwise known as ditch weed, under his new classification scheme.
Quite a lot of changes to a decades-old nomenclature, but it means we are finally getting some serious genetic information about one of the most popular drugs in the world. As Jeremy Daw of The Leaf Online writes: “Starbucks, for example, sources coffee beans from farmers spread across four continents…. In an astonishing feat of global supply chain logistics, Starbucks can now claim to have the ability to trace 94% of its coffee beans all the way back to the exact farm where they were produced.” The cannabis industry, he concludes, still has “a lot of growing up to do.”
Krymon deCesare, chief research director at Steep Hill Halent Lab in Oakland, California, a company developing more sophisticated tests for identifying the various compounds found in marijuana, told AlterNet that “sativa and indica are only really valid for describing the physical characteristics of the cannabis strain in a given environment. They are not nearly as reliable as terms for making assumptions about energy versus couch lock.” To the extent that there is a grain of truth in the basic division between the mind high of sativa and the body high of indica, as traditionally classified, deCesare believes the culprit is myrcene. Based on the analysis of more than 100,000 samples, deCesare says that his team found “consistently elevated levels of the terpenoid myrcene in C. indica as compared to C. sativa. Myrcene is the major ingredient responsible for ‘flipping’ the normal energetic effect of THC….”
Ethan Russo invokes his notion of the “entourage effect,” in which the distinctive highs normally associated with indica and sativa are in fact the result of a complex combination of many different cannabinoids and terpenes working in harmony. Teasing that apart in the lab is not a cheap or easy affair. If you don’t know your terpene levels, says Russo, than you can’t compute your relative chances of full couch-lock. And even if terpene levels are known, the same pot plant, when smoked, can still cause one person to become energized and talkative, while another person may just fall asleep. Same chemicals, different metabolisms. One person’s happy, giggly high is another person’s paranoid bad trip.
The result of this recent research is to bolster the general suspicion about medical marijuana dispensaries: The names of various marijuana varieties are not only stupid and immature, but also completely misleading and unhelpful. Coherent labeling will require much more than listing relative THC percentages. We’ve only just begun.