This article was published 27/11/2017 (1465 days ago), so information in it may no longer be current.
Walk into any marijuana dispensary in North America and ask an employee about the effects of the different varieties of bud on display, and you're likely to get an answer along these lines:
"This is Northern Lights," your budtender might say. "It's a pure indica that'll get you feeling relaxed and sleepy. Over here is Purple Haze. That's a pure sativa, and it'll give you an energetic high. Or if you want something in between, we've got lots of hybrids like this OG Kush, which is a hybrid of indica and sativa."
Popular belief among many in the cannabis community holds that there are two dominant varieties of cannabis: cannabis indica and cannabis sativa. (Cannabis ruderalis, said to be a third species, tends to get much less attention than indica or sativa.)
These different species, the story goes, have different botanical and chemical attributes that make them look different, and lead to different effects when consumed.
Sativa plants are taller, with thinner leaves, and purportedly provide a more uplifting experience described by some as a "head high."
Indica plants are shorter, bushier, have wider leaves, and purportedly give a more sedative "body high."
Then there's the issue of strains. For decades, cannabis growers have bred their plants for certain traits and named the resulting strains to distinguish them.
Strain names range from somewhat descriptive (Blue Cheese, Afghan Kush) to cryptic (XJ-13, Chemdawg) to asinine (Purple Monkey Balls, Cat Piss).
It's unclear how many strains of cannabis exist in the world, but that hasn't stopped weed lovers from trying to catalogue them.
The popular strain categorization website Leafly, for example, lists thousands of strains, labelling them as indicas, sativas, or hybrids, and describing their pharmacological effects as reported by users.
"Blue Dream, a sativa-dominant hybrid originating in California, has achieved legendary status among West Coast strains," reads one such description on Leafly.
"Crossing a Blueberry indica with the sativa Haze, Blue Dream balances full-body relaxation with gentle cerebral invigoration. Novice and veteran consumers alike enjoy the level effects of Blue Dream, which ease you gently into a calm euphoria."
Chemical makeup vs. physical differences
Nick Jikomes, principal research scientist at Leafly, acknowledged that the practice of classifying cannabis strains as indica, sativa, or hybrid doesn't necessarily correspond to scientific reality.
Still, he points out that the system means something to cannabis users.
"What consumers want to know is, will something affect me differently, if it's type A versus type B? And I think the answer to that is, yes, there are things that are different and will affect you differently, but they probably don't map onto the indica-sativa-hybrid distinctions that we make," he said.
Jikomes said he's researching ways to categorize cannabis products based on their chemical makeup, rather than their physical differences.
"My view is that sativa and indica and the morphological distinctions that exist between strains is really most appropriate for someone thinking about growing the plant, or who's interested in the botanical side of things," said Jikomes.
A botanist's take
Botanists still haven't reached a taxonomical consensus on whether cannabis sativa is a single species with a great deal of variation, or whether it should be classified as a multiple distinct species, according to Canadian botanist Jonathan Page. He's the founder and CEO of cannabis testing firm Anandia Labs, and has studied the genetics of cannabis extensively.
Page and his colleagues studied the relationship between cannabis strains and their purported genetics in a 2015 paper published in PLOS One. The researchers scanned the genetics of 83 samples of drug-type cannabis, and 43 samples of industrial hemp-type cannabis.
The research found a moderate correlation between the strains' genetic structures and the purported ancestry of the strains — but in some cases, strains that were said to be 100 per cent indica or 100 per cent sativa were genetically almost identical.
"The inaccuracy of reported ancestry in marijuana likely stems from the predominantly clandestine nature of cannabis growing and breeding over the past century," said the paper. "Our results suggest that the reported ancestry of some of the most common marijuana strains only partially captures their true ancestry."
"The inaccuracy of reported ancestry in marijuana likely stems from the predominantly clandestine nature of cannabis growing and breeding over the past century."
Those findings tend to resonate differently with people who believe in the indica-sativa divide and those who are more skeptical, Page said, but he tends to side with those who see some kind of observable differences between the supposed species of cannabis.
"And that may be based on one chemical or it may be based on a mixture of different things," Page said.
"But I think there's probably something to it, and we haven't really boiled it down to the chemical and genetic differences that can really allow us to accurately discern those differences yet."
The indica-sativa divide, said Page, is "deeply embedded" in marijuana culture.
"It has a lot of proponents, and a lot of people base what they consume or what they grow on that basis," he said.
In the coming years, Page believes, the way in which we classify different types of cannabis could undergo a revolution.
"In 10 or more years' time — maybe this is controversial today — I think the concept of strains will be a thing of the past, because it really arose out of the world of no regulation and no oversight," said Page.
Instead, he said, the cannabis community might start describing the drug using more agricultural terms such as "varieties" and "cultivars," with the differences between them identified by genetic analysis.
Still, Page believes the practice of assigning names to different types of cannabis will live on.
"We'll still have names because we have names for grapes and apples and breeds of dogs and everything," he said.
"Humans name things."