The sands of time are passing quickly. In a mere two days, adults in Canada will be free to legally purchase recreational cannabis in licensed dispensaries and on websites in provinces where online sales are permitted. Though legalization has been a long time coming, the expectation is that it'll result in billions of dollars in added annual sales.

The assumption that the marijuana industry will be a resounding success is very much reflected in the share price of most pot stocks. For example, the North American Marijuana Index, which tracks the performance of a basket of growers, ancillary players, and makers of cannabinoid-based drugs in North America, has risen by more than 700% since February 2016. Investors have practically been able to throw a dart and come out winners.

However, moving forward, it's all about marijuana stocks differentiating themselves from an otherwise crowded field. While not all marijuana stocks are worth buying, and the industry itself could be in a valuation bubble, there are a few pot stocks that are truly unique and worth keeping on your radar. Here are five of those stocks.

A large storefront sign that reads "marijuana"

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GW Pharmaceuticals

Whereas most investors are laser-focused on recreational legalization, they may be forgetting that GW Pharmaceuticals (NASDAQ:GWPH) made history on June 25th when its lead cannabidiol (CBD)-based drug Epidiolex was approved to treat two rare forms of childhood-onset epilepsy by the Food and Drug Administration. This marked the first time in history a cannabis-derived drug received an approval from the FDA, although synthetic tetrahydrocannabinol drugs like dronabinol have been given the green light before.

GW Pharmaceuticals is currently the only marijuana stock with a cannabis-derived drug ready for patients. Perhaps best of all, Epidiolex was recently classified by the federal government as a Schedule V drug, which is the lowest scheduling, and therefore most liberal classification, the drug could have received. There's a chance that GW Pharmaceuticals could spark the change that leads to additional medical marijuana research in the U.S., as well as a rescheduling of CBD, the non-psychoactive cannabinoid known for its perceived medical benefits.

Although GW Pharmaceuticals' path to success won't be free and clear, a surge in revenue is clearly on the horizon.

Four vials of cannabidiol oil lined up on a counter

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KushCo Holdings

If there's a marijuana stock that perfectly embodies the ancillary movement, it's KushCo Holdings (OTC:KSHB).

KushCo is probably best known for its tamper- and child-resistant packaging for the cannabis industry. The company is currently working with more than 5,000 cannabis businesses around the world to assist with packaging solutions. In Canada, for instance, Health Canada laid out a laundry list of packaging, labeling, and branding requirements that growers and retailers would need to follow in order to remain compliant. KushCo's responsibility is to ensure that retail items remain compliant, while at the same time providing branding and marketing solutions to growers to help their products stand out.

More recently, KushCo has pushed into the hydrocarbon gas and solvent space with the acquisition of Summit Innovations. Hydrocarbon gases are needed in the production of high-margin cannabis oils, while solvents are used in the production of concentrates, such as BHO (butane hash oil). By centering itself in niche, but supportive, categories to the marijuana industry, KushCo should be in excellent position to capitalize on a rapid rise in sales.

A man in a white coat and stethoscope holding a baggie of dried cannabis in one hand, and green capsules in the other hand

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Liberty Health Sciences

Another unique play would be small-cap Liberty Health Sciences (OTC:LHSIF), which is based in Canada but does its business in Florida's medical cannabis market.

What makes the company so intriguing is that it holds one of just 14 cultivation licenses for medical marijuana producers in Florida. Having such a small number of licenses really limits Liberty Health Sciences' competition and gives the company a clear path to success. It ended the most recent quarter with nearly 10,000 patients, a 112% increase from the previous quarter, and nearly doubled revenue to $2.2 million.

More importantly, Liberty Health is constructing what'll be the largest grow farm in the state, with production capacity of around 225,000 square feet when all is said and done. Already controlling around 15% of Florida's medical marijuana market share, Liberty envisions increasing its stake to 20% or higher, as well as expanding its model into other legalized states. Given Florida's potential with its generally older population, medical marijuana could prove a very profitable venture for this company.

A freshly trimmed cannabis bud being held in a gloved left hand.

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CannaRoyalty Corp.

No discussion of unique marijuana stocks is complete without a mention of CannaRoyalty Corp. (OTC:ORHOF), the Canadian-based former investment company that's looking to corner a lucrative market within California.

Rather than operating as a royalty company, CannaRoyalty is now focused on becoming one of just a handful of cannabis distributors in California's lucrative weed market. Although there are thousands of brands competing in hundreds of licensed dispensaries, there will be just a small handful of licensed distributors able to get cannabis from Point A to Point B. CannaRoyalty is aiming to acquire companies to grow its distribution market share in California.

Interestingly enough, California has a genuine chance to become a market with higher sales than all of Canada. While dispensary licensing delays and oversupply have hurt the potential of companies like CannaRoyalty, this should be resolved within the next couple of quarters. Like KushCo, it's a unique niche player that marijuana stock investors are going to want to keep a close eye on.

An indoor commercial cannabis grow farm in a greenhouse

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OrganiGram Holdings

Feel free to call me biased since it's my favorite marijuana stock, but among the growers I find OrganiGram Holdings (NASDAQ:OGI) to be the most unique.

For starters, OrganiGram is based in Atlantic Canada, whereas pretty much every major grower is based in British Columbia, Quebec, or Ontario. This has kept OrganiGram largely off Wall Street's radar, yet gives the company some unique geographic advantages when it comes to serving Atlantic-based consumers.

OrganiGram also (arguably) makes better use of its growing space than any other grower in Canada, period. The company's proprietary three-tiered growing system should allow for 113,000 kilograms of weed at peak production, yet will use just 480,000 combined square feet of grow space to achieve this amount. That should be good enough to place OrganiGram among the top 10 growers by yield in Canada, when it's up to full speed in 2020.

Given its focus on alternative cannabis products, which have considerably higher margins than dried cannabis, and the expectation of lower long-term growing costs than its peers, OrganiGram is the unique grower you'll want to monitor.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.