"They call things Purple Kush, but Purple Kush does not mean anything," said Sean Myles, a professor of agricultural genetic diversity at Dalhousie University and co-author of the 2015 study, over the phone. "There are so many exceptions, and the correlation is so weak, that putting a number on a bag and saying, 'This is a 50/50 hybrid of indica and sativa,' is highly, highly dubious."Most folks probably think strains are genetically similar if they have a similar name, but this too can be misleading. For example, "haze" varieties of weed are expected to be more sativa-dominant. But, according to the 2015 study, while Super Silver Haze and Neville's Haze are reported as being sativa-dominant and deliver, others, like Domina Haze, are actually more genetically similar to indica-dominant "kush" strains, like Master Kush or King's Kush. A full 35 percent of strains the researchers tested had more genetic similarities to differently-named varieties than to similarly-named ones.
"It's crazy, it's absolutely nuts. I mean, you couldn't run an industry like this anywhere else, except for cannabis"
Illustration: Nate Milton
Weed dispensaries have popped up in many major cities like goose shit in the springtime, and an oddly stressful ritual has entered many of our lives: choosing a strain of the devil's lettuce to roll into a jazz cigarette. The conversation typically goes something like this: Dispensary lady: My guy, today we've got some Jack Herer, which is sativa-dominant and has a cerebral and talkative high, or Banana Clip, which is close to a 50/50 hybrid and will give you the body buzz of an indica with some of the effects of a sativa. We've also got God's Green Crack and Mango Dream. Me, internally: Hm, seems fake. Me, externally: Banana Clip, please.
After sampling the bud (this actually happened), the hybrid Banana Clip felt suspiciously similar to a strain I'd previously tried, which was supposedly an "almost pure" strain of another variety. I also couldn't find any trace of a strain called Banana Clip on the web, and I suspect I was smoking AK Banana. Just what the hell was going on inside this disorienting kaleidoscope of primo greens, I wondered? Is any of this even, well, real?Unfortunately, scientifically speaking, weed strains are mostly bullshit.
What Is a weed strain?But let's back up for a second. For the uninitiated, a "strain" of marijuana is generally understood to be a unique genetic blend—a hybrid—of the two (supposedly) main types of weed, sativa and indica, with some additional tweaks. They all promise different physical effects. The time-tested rule of thumb for stoners, though, is that sativas have a more cerebral and wakeful high, while indicas are good for zoning out on your couch for hours and watching Planet Earth.I informally polled a handful of coworkers and their friends, and most believed that the general differences between sativa and indica-dominant strains are real. Some said they keep coming back to a particular cannabis strain, like Jack Herer. One person who asked to go by "Doug" said they prefer "pure" sativa strains.How did dispensaries influence weed names?Notably, most folks said that before dispensaries moved in, they didn't really care about which variety of weed they smoked—pot was pot.
This might be because, when it comes to the genetic differences between a strain of weed that's supposedly 30 percent indica and 70 percent sativa, or vice-versa, science has already strongly suggested that it's a big lie. A 2015 study by Canadian scientists looked at 81 marijuana strains and found that the reported sativa-indica split rarely matched their actual genetic makeup.
"When you go into a grocery store and there's a big pile of apples labelled as Honeycrisp, you expect that they're actually Honeycrisp apples." Myles said. "You can't just throw McIntosh apples in there and sell them for $4.99 a bag.""It's crazy, it's absolutely nuts," he continued. "I mean, you couldn't run an industry like this anywhere else, except for cannabis."
Do different cannabis strains affect me differently?The short answer is yes—but scientifically, we don't know how, or why, or even if sativas and indicas exist in a pure form."We don't really know if indica or sativa exist in their purest forms," said Myles. "In terms of what botanists have described in nature, we can't get ahold of samples where we can be 100 percent confident that its a sativa or indica. This plant has been shuffled through so many human hands over so many millennia." We may loosely call things "indica" or "sativa," Myles continued, and that's a fair rule of thumb for describing their physical traits and psychoactive effects. But since nobody was keeping track of marijuana with the methods of a modern agriculturist some 5,000 years ago, we don't know what a "pure" sativa or indica really is, DNA-wise, he said. Who's to say what the defining characteristics of a pure sativa or indica really are? So, "pure" sativa or indica strains are also probably fictions. Still, the scientific literature suggests that plants with more sativa ancestry have higher levels of tetrahydrocannabinol, or THC, than indica-dominant plants, which have higher levels of cannabidiol, or CBD. As for what these compounds do, many studies have shown basically the same thing: THC gets you high, and CBD does not. It's not totally clear what CBD does to the brain, but a 2008 study showed that, in high doses, CBD and THC can work together, with CBD alleviating some of the anxiety reported after THC ingestion. Tetrahydrocannabinol (THC) & Cannabidiol (CBD) content in weedAccording to Myles, it's better to think of weed as existing on a spectrum of sativa-ness and indica-ness, and the most accurate way to describe weed is its THC and CBD content rather than its genetic heritage. This is how government-approved medicinal grow-ops do business. Bedrocan, for example, doesn't name its pot after marijuana strains you find on the street, and indicates THC and CBD content. For example, instead of telling someone they're about to smoke Purple Kush, it's better to say they're about to smoke "Bedrobinol," one of Bedrocan's trademarked products, which has a standardized THC content of 13.5 percent and less than 1 percent CBD. It's less fun, but at least you know what you're getting. Going forward, knowing what different strains of weed and weed strain names actually mean, and will do to you, will require rigorous genetic indexing, and standardizing the creation of new strains. Myles hopes that marijuana becoming more acceptable (and legal, at least in some places) will help with this. "As we legitimize the use of cannabis, the science necessarily catches up—it's not going to stay in the dark forever," he said. "One day you'll be able to go to a dispensary and get Lemon Skunk, and be sure that it's Lemon Skunk." Or Banana Clip. Here's to the future. Subscribe to Science Solved It , Motherboard's new show about the greatest mysteries that were solved by science.