People well acquainted with marijuana will likely know the difference between sativa and indica, which are the two species of the cannabis plant from which most varieties or “strains” are bred. “If you go into any dispensary, you’ll hear sativa described as being activating or uplifting and euphoric, while indica is said to be calming or sedating,” says Sean Myles, a research chair and associate professor of agricultural genetics at Canada’s Dalhousie University.

Depending on the type of experience you’re looking for, you may lean — or be guided by a dispensary employee — toward a sativa- or indica-dominant strain, or even a “pure” strain, which you may be told is 100 percent one species or the other. For example, Purple Kush is usually marketed as 100 percent indica, while White Widow is often described as a 60–40 percent split between the two species.

All of this is fantastic product marketing. It suggests a level of botanical and biochemical precision that is comforting to consumers — whether you’re using cannabis recreationally or to relieve an affliction (or a bit of both). Unfortunately, a lot of it is bunk.

“The evidence we have to date shows that indica and sativa labeling as currently applied to consumer products is not a reliable indicator of genetics or ancestry, or even of the plant contained within the package,” Myles says.

In a 2015 study in PLOS One, Myles and colleagues genotyped more than 80 commercially available varieties of cannabis. They found that the indica/sativa distinctions advertised on a product’s packaging were wildly inaccurate. “Some strains labeled 100 percent indica were more closely related to a strain labeled 100 percent sativa than any other indica strains in the data set,” he says.

Maybe more troubling: There was little genetic consistency among strains being sold under the same name. “So, all these strains — Neville’s Haze, Alaskan Ice, Bubba Kush — in a third of the samples we genotyped, the strain was more closely genetically related to another strain with a different name than to one with the same name,” Myles says.

Myles typically conducts research on the genetics of grapes and apples. He says the mislabeling of commercial cannabis products is like walking into a grocery store and finding that a third of the bottles of pinot grigio are filled with sauvignon blanc or that the pallets of pricey Honeycrisp apples are loaded up with McIntosh. “What we saw with the cannabis strains is really unusual in the world of agriculture, especially when you’re talking about a $30 billion industry,” Myles adds. Throw in the fact that many people use marijuana as medicine, and all this becomes a lot more alarming.

Experts say the “sativa” and “indica” distinctions sprouted, so to speak, from legitimate botanical distinctions. “Cannabis sativa, or ‘cultivated cannabis,’ was the scientific name applied by [the 18th-century Swedish botanist Carl] Linnaeus and others before him to European hemp,” says Ethan Russo, a neurologist and director of research and development at the International Cannabis and Cannabinoids Institute, a for-profit cannabis education and research firm based in the Czech Republic. Later, Russo says, a French naturalist applied the term Cannabis indica to a narrow-leafed variety of hemp from India that “in no way resembles” what people today call indica.

“The terms ‘sativa’ and ‘indica’ are nonsense as applied in current common parlance and have no scientific validity.”

Russo says there’s a lot of disagreement among plant geneticists about whether indica and sativa are separate species of cannabis or whether they’re really just two varieties of a single species. But none of this matters for those who sell or use cannabis. “What is important is the biochemical profile and pharmacological effects of a given type of cannabis preparation, as this will determine the expected effects,” Russo says. And from what he and others have turned up, the indica/sativa distinctions don’t mean much at the biochemical or pharmacological level. “The terms ‘sativa’ and ‘indica’ are nonsense as applied in current common parlance and have no scientific validity,” Russo says.

THC and CBD are the two primary psychoactive compounds in cannabis and the ones most users associate with the drug’s mind and body effects. Traditionally, sativa is thought to contain a higher ratio of THC to CBD, while indica is considered a CBD-heavy species. Users — including medical patients — are often directed toward one variety or the other based in part on these distinctions.

But a study published last year in Nature Scientific Reports found the THC-to-CBD ratios in all commercial cannabis strains are more or less identical and can’t account for each strain’s benefits or effects. “Indica strains do not have predictably higher CBD than sativa strains,” says Elizabeth Mudge, co-author of the study and a PhD student in chemistry at the University of British Columbia. In fact, Mudge says there are many so-called indica strains that have zero or minimal CBD content. In any case, she says there is “limited research” backing the idea that a strain’s pharmacological effects can be consistently predicted based on its cannabinoid content alone.

“While THC gets most of the attention as the primary psychoactive component of cannabis, there are additionally over 100 other possible cannabinoids and 200 terpenoids in any given cannabis chemovar,” Russo says. The types and amounts of each of these chemical compounds help determine the effects of a specific cannabis product, he adds.

But no one — not the people growing cannabis and not the people selling it — know the exact (or even the approximate) types or quantities of these compounds in a given product. “The quality control in the industry currently leaves a great deal to be desired,” Russo says, referring to this as “another unfortunate byproduct” of prohibition.

To help remedy the problem, he says all cannabis products should undergo chemical analysis and come with a certificate — similar to the information listed on the side of any prescription drug or OTC medication — detailing the drug’s cannabinoid and terpenoid contents, as well as the presence of pesticides, bacteria, fungus, heavy metals, and other contaminants. While each person’s unique neurochemistry can affect the way they respond to a particular variety of cannabis, Russo says this kind of certification would go a long way toward helping people (and dispensary workers) choose the type of cannabis that suits their needs.

As of today, most cannabis consumers and merchants are largely flying blind. “There may be some truth to the idea that some strains are uplifting versus sedating,” Myles says. “But whether that correlates to what the person behind the counter is telling you remains a completely open question.”

He adds, “I believe the correct term for the current state of cannabis labeling is ‘shitshow.’”