In both the legal and illegal cannabis market, the type — or "strain" — of marijuana has taken on great significance for consumers. As the logic goes, if you're looking for a specific type of high or medical benefit: there's a strain for that.

Sonya Yruel/Drug Policy Alliance - drugpolicy.org

But recent research has raised questions about the genetic consistency of strains sold under a variety of names such as Blue Dream, Sour Diesel, or Girl Scout Cookies. It turns out that the same cannabis labels sold at different dispensaries might contain totally different sets of ingredients.

"The way that seeds work in the cannabis world is more like the human population," Mowgli Holmes, chief scientific officer of the cannabis biotech company Phylos Bioscience, told ATTN:. "Every seed is a unique child from two different parents — and there's just this incredible diversity because the plants spread all around the world and then all of those different varieties came back and recombined into this genetic swirl on the West Coast of the U.S. and in Holland."

AP/Robert F. Bukaty - apimages.com

What's more, geneticists aren't even confident that strains are being accurately labeled based on their cannabis family, according to a 2015 study published in PLOS ONE. There are three main classes — indica, sativa, and hybrid — and each produces distinct effects. For example, Indicas tend to make you feel sleepy and hungry, whereas sativas are associated with an energetic, cerebral high. Those families certainly exist, but they aren't represented in the consumer market.

This isn't due to deception on the part of cannabis growers or businesses, though. It's largely the product of marijuana's longstanding criminalization. Unlike most agricultural products, which have undergone extensive genetic testing for centuries, researchers are just now starting to map the genetic makeup of cannabis products.

Wikimedia - wikimedia.org

And, as FiveThirtyEight recently reported, there's a lot of ground to cover. During the past century of criminalization, the genetic diversity of cannabis has rapidly flourished. Now most "strains" are hybridized — containing crossbreeds of different seeds with countless combinations of the plant's hundreds of ingredients. There's no "official" genetic identity for a given strain either, so there's no definitive way of knowing what authentic "Sour Diesel" actually is.

This confusion over cannabis strains is bad news for medical patients. Trusting that a strain contains that right proportion of ingredients to produce a desired effect  — whether sedation, pain relief, or reduced frequency of seizures — is a key component of the patient's treatment. 

Until the industry is standardized, there's virtually no way of telling whether the label actually matches the product. Yet strains are commonly promoted as having distinct physical and psychoactive effects so consumers naturally assume that when they order Blue Dream at any dispensary, they're getting a product that delivers those promised effects.

"In a general way, we have a sense that the names are totally, totally wrong at least 30 percent of the time," Holmes said. "The real challenge is for consumers and especially for patients who can't get consistent products."