On paper, if you were setting out to choose a marijuana variety to try, ‘Lamb’s Bread,’ “a bright green and sticky sativa strain,” seems like as good a place to start as any.

Though perhaps not at bedtime.

Originally bred in Jamaica, it has “sharp woody notes mixed with sweet, earthy soil,” The Leafly Guide to Cannabis tells us. A contributor writes that it “really makes me feel energetic, but in a good way … just positive energy.”

Canadian scientists ordered some, along with dozens of other varieties, from grey-market suppliers and licenced producers, in 2015. They could see what varieties they ordered were labelled as, but what did that mean? DNA testing would show the answer.

The result: the Lamb’s Bread sample was nearly identical to a Cannabis indica sample from Afghanistan, which, Leafly tells us, should be “physically sedating, perfect for relaxing with a movie or as a nightcap before bed.”

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In over a third of the comparisons the scientists made between samples, a strain was “more closely related to a strain with a different name than it is to the strain with the same name,” explains Dalhousie University plant scientist Sean Myles, one of the study’s authors.

Strains that were supposed to be different were nearly the same, while strains that were supposed to be the same were different. The more the scientists looked at the problem, the less reliable the labels turned out to be.

“That means that even though people are using the same name, Master Kush, from one producer to another, it’s not a very good predictor of whether they’re actually genetically similar. That means that they’re probably not very similar in their effect, either.”

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“The strain names provided by suppliers are not likely to reflect any true or meaningful genetic identity.” Tweet This

The confusion is partly a result of decades of cannabis breeding happening in grey- or black-market conditions, the study’s authors write. If you’re worried about the police kicking down your door, it’s hard to keep strains genetically consistent and the same between growers in different countries.

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Who originally developed a strain, and where? If the wrong person knowing the answer could net someone years in prison, it may be hard to find out.

“The inaccuracy of reported ancestry in marijuana likely stems from the predominantly clandestine nature of Cannabis growing and breeding over the past century,” the study’s authors wrote. “Our results suggest that the reported ancestry of some of the most common marijuana strains only partially captures their true ancestry.”

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In a black market, “standardization doesn’t come from anywhere,” says Canopy Growth vice-president Jordan Sinclair.

“There’s an incentive to tell people that you’ve got whatever the hot genetic of the day is. A couple of summers ago, there was a popular hip-hop song that was talking about one cannabis strain. All of a sudden, every drug dealer has that cannabis strain.” Tweet This

When it started growing cannabis, Canopy bought seed from small growers.

“They told us what they had, we took them at their word, and we grew it out. Sometimes you would grow out a pack of those seeds, and there wasn’t a ton of similarity between the 20 plants that came out of the same package — seeds that were labelled the exact same way.”

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Another reason is that while strains are sometimes propagated through clones (which keeps plants identical), they can also be grown from seed (which doesn’t) while retaining the original strain name.

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“In agriculture, it’s completely outrageous that you’d just be able to label everything you want, and stick an ancestry on it that doesn’t correspond to the real genetics,” says Myles, an expert on apple genetics. “You can’t do that.” Tweet This

“It’s kind of like going to one place and buying a bottle of pinot noir, and going to another place and buying a bottle of pinot noir, and for those to be completely different grape varieties. One threw cabernet sauvignon in it, and the other threw chardonnay.”

The inconsistency raises the question of how legal cannabis retailers will handle varieties. The Ontario Cannabis Store, for example, has 32 different suppliers. How would it know if it was offering 32 different varieties, all called Hindu Kush by their producers?

“OCS’s product pages will include information such as species (indica/sativa/hybrid), THC and CBD content, terpene profile and the brand name of the product,” OCS spokesperson Daffyd Roderick wrote in an e-mail. “We will not provide genetic information on the product but rather link to the licensed producer for more in-depth product information.”

In an exchange of e-mails, Roderick would not say how, or whether, the OCS planned to verify what strain it was selling under a given name.

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With legalization less than two months away, and Canadians closer to choosing between Granddaddy Purple, Sour Diesel or Cannatonic in legal stores, the study raises questions about what the labels mean.

Accuracy would seem to matter.

Leafly describes ‘Northern Lights‘ as an Indica variety, whose “psychoactive effects settle in firmly throughout the body, relaxing muscles and pacifying the mind in dreamy euphoria,” while ‘Durban Poison,’ a Sativa variety, “lights a fire under your creativity, boosting intrigue and engagement in writing, drawing, music and other creative activities.”

Canopy worked around the problem by breeding their own varieties and giving them new names. In the wider market, Hindu Kush could mean different things, but Canopy’s Bakerstreet, which is derived from it, will be a consistent product.

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Marijuana genetics is such a mess that we should just start fresh, Myles argues.

“We’ve got more evidence coming up from Dutch coffee shops, and the results are largely the same. All in all, the evidence that I’ve seen, and I only base my opinion of these things on evidence … is that they should abandon all the labels.” Tweet This

There is little evidence that indica and sativa — presented to the public as relaxing and stimulating, respectively — are actually different, Myles says.

“Unfortunately, the customers have come to believe that indica and sativa are actually meaningful labels, and what we’re demonstrating is that, at least at the genetic level, and we have additional evidence coming out at the chemical level, they are not being meaningfully labelled at all.”