In the United States, cannabis may be either a legal agricultural crop or a controlled substance — it all depends on whether the plant is classified as “marijuana” or “hemp.”

With the passage of the 2018 Farm Bill, the US is experiencing a huge cultural shift in mainstream attitudes towards cannabis. And with these changes, more and more people are turning to the cannabis plant for materials, nutrition, recreation, and medicine.

In most parts of the country, though, only cannabis plants that are classified as “hemp” are legal. Those classified as “marijuana,” on the other hand, are either strictly controlled or forbidden outright. 

This much is clear: hemp and marijuana are two different things. But what makes them different? 

In this article, we’ll look at how and why the definitions of these words have changed over time. Then we’ll discuss what you need to know about hemp and marijuana when using CBD oil or medical cannabis.

But first, let’s get to know the cannabis plant — in all of its many forms.

What is Cannabis?

Cannabis is a botanical genus that contains several varieties of plants. These have gone by a number of scientific and vernacular names, reflecting both different physical characteristics, different uses, and different chemical profiles. In the United States, though, the most common terms for cannabis are “marijuana” and “hemp.” 

Cannabis plants naturally have fibrous stalks. Over centuries, humans practiced selective breeding to develop plants with stalks that were even longer and more fibrous. They processed those fibers to make cloth, rope, paper and other products. These fiber-producing types of cannabis came to be known as “hemp,” and may have been the first plants that humans cultivated for fiber. 

Other types of cannabis plants caused intoxication when inhaled or ingested. Growers cultivated these types to produce more potent flowers for medicinal or therapeutic purposes. In the US, the variants used for their psychoactive properties eventually became known as “marijuana.”

Over time, hemp and marijuana developed very different physical characteristics. Still, there are some things that all cannabis plants have in common.

Anatomy of the Cannabis Plant

To understand the differences and similarities between hemp and marijuana, it helps to know your way around the structure of the cannabis plant. Read on to learn about the main parts of the plant, along with a few of their primary uses.


While they are often ignored by contemporary consumers, the roots of the cannabis plant have long been used in traditional medicine for their anti-inflammatory compounds. These preparations include infusing teas and topicals with the cannabis root.

While the roots are not a source of cannabinoids, traditional remedies suggest therapeutic applications for other components of this part of the plant.

But that’s not all. The roots of growing cannabis plants can also play a role in a process called phytoremediation. Basically, they draw pollutants from the soil to remediate contaminated sites. 

That’s because hemp is a bioaccumulator that absorbs whatever is present in the soil where it grows. This makes it an effective tool for cleaning up heavy metals and other unwanted chemicals in the soil. 


Traditionally, European hemp was grown for the bast fibers and the woody hurd found in the stalk.

Today, these bast fibers can be found in apparel, bags, rope, canvas, and carpets. The hurd, on the other hand, is used for building materials like cement, insulation, bioplastics, animal bedding, and paper.

The stalk is not a good source of cannabinoids in either hemp or marijuana — although they can be present in trace amounts. That’s because cannabinoid-producing trichomes (more on those later) don’t grow in great numbers on the stalks.


In both hemp and marijuana, the leaves are much less rich in cannabinoids than the flowers. But leaves may be used for cannabinoid extraction for some products, especially those made for the CBD market. There are two types of cannabis leaves.

Fan leaves

These are the large, pointed leaves that have become iconic in cannabis culture. The powerhouse of the plant, their role is to capture sunlight for photosynthesis.

The fan leaves are not a major source of cannabinoids in either hemp or marijuana, and their bitter flavor makes them an unpopular food ingredient for most people.

Still, fan leaves can be juiced or used in tea for those who want to benefit from their nutritional value and trace amounts of cannabinoids.

Sugar leaves

Sugar leaves are small, resinous leaves that form around the flowers of the cannabis plant. They are coated in trichomes, which look like small hairs or crystals to the naked eye. These are the structures that contain cannabinoids like THC and CBD. 

Growers tend to remove sugar leaves from smokable cannabis buds, though, despite their cannabinoid content. That’s because they make the smoke feel harsher, and they add more bitter flavors to the smoke. But sugar leaves can be used to make other types of extracts and infusions.


The cannabis flower contains most of the plant’s cannabinoid content. That’s because the flowers are covered in resinous, sticky trichomes. These are the part of the plant responsible for cannabinoid production, and while they are present to some extent on all of the plant’s exterior parts, they are, by far, most densely located on the flower.

But not all cannabis flowers are equal. The plant has both male and female varieties, and the flowers of each one play different roles in the plant’s reproductive cycle.

Female cannabis plants have much higher cannabinoid content than those of the male plant. In marijuana varieties, flowers of the female plants are smoked or used for extracts.

CBD hemp growers also favor female plants for maximum cannabinoid production. These flowers may be smoked, vaped, or used to make extracts like CBD oil. 

In the presence of male plants and their pollen, female plants will produce seeds. That causes lower cannabinoid production, so growers who are looking for high cannabinoid potency tend not to grow male plants.

Mature female cannabis flowers don’t look much like ornamental flowers such as daisies or roses. Rather, they are dense, conical clusters that may contain visible small leaves and fine hair-like structures. Their color tends to be deep green, sometimes with other colors such as purple, pink, or gold. 

Male flowers, on the other hand, offer lower cannabinoid content and are visually very different from female buds. These look like clusters of pollen sacs rather than tightly formed buds.

Some people want to ban outdoor cultivation of male industrial hemp plants. That’s because accidental cross-pollination with other growers’ cannabinoid-producing plants can ruin the harvest by triggering seed production.


Seeds are generally undesirable in marijuana and CBD hemp varieties of cannabis, but other types of hemp can be grown specifically to produce them.

Hemp seeds are very nutritious, and have a number of culinary uses. They can be eaten raw or ground into meal to be used as an ingredient. In addition, hemp milk is gaining popularity as a plant-based dairy alternative, and hemp seeds are also a popular ingredient in protein powders.

Beyond their culinary uses, hemp seeds can also be found in cosmetic and personal care products. Often listed as “cannabis sativa seed oil,” hemp seed oil has been growing in popularity in the beauty and skincare industry since the passage of the 2018 Farm Bill.

Cannabis seeds, whether they come from hemp or marijuana types, are not a source of cannabinoids because they do not have trichomes. But because the seeds are formed inside the flower, there is the potential for contamination during processing. 

But don’t worry, you’re not going to get high from your hemp-based protein powder. Fortunately for those of us who enjoy products like hemp milk and hemp seed granola, the cannabis seeds that are grown for food come from industrial hemp varieties that were bred for extremely low cannabinoid production. 

Beyond CBD and THC: Cannabis Chemistry

Now you know the parts of the cannabis plant. But to get a deeper understanding of what botanists, consumers, growers, and lawmakers have meant by the terms “hemp” and “marijuana,” we need to go even deeper. 

After all, the cannabis plant’s intoxicating potential is a big reason for its current existence in a legal gray area. And that’s all down to the chemical makeup of the plant.


Cannabis contains chemical compounds called phytocannabinoids that may be used for medicinal and therapeutic purposes. That’s because they interact with the endocannabinoid system (ECS), a network of transmitters and receptors found throughout the body.

Phytocannabinoids closely resemble endocannabinoids, which are substances the body produces naturally. This allows them to interact with the ECS for a broad spectrum of potential health benefits.

The most well-known phytocannabinoid is delta-9 tetrahydrocannabinol, or THC. This is the main chemical responsible for marijuana’s intoxicating effects. Its psychoactive notoriety is the reason that, until recently, most cannabis research has only focused on the effects of THC.

But lately, that’s been changing. Researchers and consumers alike are starting to pay more attention to another phytocannabinoid: cannabidiol, or CBD

Far from producing the mind-bending experiences associated with THC, the effects of CBD are associated with relaxation and focus, as well as a gentle mood enhancing effect. And new scientific studies suggest a range of additional health benefits from CBD, including relief from pain and seizures.

These two phytocannabinoids, along with many other trace cannabinoids, are present in both hemp and marijuana. Generally speaking, though, marijuana varieties produce much higher levels of THC.


Terpenes are aromatic compounds that occur in a variety of plants. They contribute to the characteristic scents and flavors of everything from cinnamon to lavender, and they are responsible for many of the different aromatic profiles of cannabis strains.

Research indicates that terpenes may also have medicinal properties, including helping with mood and other brain functions. 

The interactions between the cannabinoids and terpenes in cannabis products may result in increased benefits compared to any one substance alone. This is known as the “entourage effect.”

Other plant compounds

In addition to cannabinoids and terpenes, one 2005 article listed nearly 300 chemical constituents of cannabis. These include amino acids, proteins, enzymes, fatty acids, flavonoids, and more.

With the current emphasis on cannabinoids and terpenes, there has been less research on the other chemicals in cannabis. But that could change in the future.

For example, we already know that while flavonoids are found in a variety of plants, there are flavonoids that have only been identified in cannabis. These compounds occur in very small amounts, but they may have medical applications of their own. According to one study, two of these flavonoids — Cannaflavin A and B — have shown potent anti-inflammatory activity in animal cell models.

Cannabis in the US: The Origins of the Hemp vs. Marijuana Conflict

Hemp played a major part in sea exploration, thanks to its role in producing fiber for rope.

And when Spanish colonists first brought cannabis to the Americas, humans had already been cultivating the plant for centuries. 

And at that time, the cannabis plant’s reputation couldn’t have been further from its current notoriety. In fact, cannabis was so respectable that President George Washington famously planted hemp at Mt. Vernon. He wasn’t the only founder to capitalize on hemp; Thomas Jefferson and James Madison were also cannabis farmers.

But while cultures in other parts of the world had long been using cannabis for medical purposes, it wasn’t until much later that Europeans (and colonists in the Americas) learned that cannabis was good for more than just rope and textiles.

In the 1830s, an Irish physician traveled to India. There, William Brooke O’Shaughnessy learned about medical applications for cannabis, and he brought this knowledge back to the English-speaking world.

Within a few short decades, cannabis had become widely available as a remedy. In fact, the pharmaceutical companies that later became Eli Lilly and Pfizer produced cannabis preparations for a variety of ailments.

Cannabis prohibition and the introduction of “marihuana” 

Until the early 20th century, cannabis remained widely available. This agricultural crop was in high demand for medicine and fiber.

But the temperance movement of the early 20th Century reflected the growing concern and disapproval surrounding mind-altering substances. After alcohol became illegal, activists set their sights on other intoxicants.

Meanwhile, Mexican immigrants introduced the practice of smoking cannabis in cigarettes or pipes. While cannabis products like tinctures had long been on the shelves of every apothecary, smoking cannabis was a new trend in the US. And along with the new style came a new word for the plant: “marihuana.” (The contemporary spelling of “marijuana” with a “j” came later.)

Because hemp and cannabis were so well known, anti-drug activists may have decided to use the foreign-sounding word “marihuana” to stigmatize the plant. With the head of the Federal Bureau of Narcotics claiming that there was an increase in people smoking something called “marihuana,” the stage was set for a law intending to curb cannabis agriculture.

In 1937, the Marihuana Tax Act instituted a tax on the sale of cannabis. In addition to the products that were intended to be used as medicines, the tax also applied to agricultural hemp grown for rope, textiles, and other non-consumable products.

And decades later, the Controlled Substances Act of 1970 made “marihuana” a Schedule I drug.

Hemp vs. Marijuana: Changing Definitions

Historically, the difference between the definitions of “marijuana” and “hemp” have been both functional and cultural.

The term “hemp” was associated with industrial uses of the cannabis plant. Hemp varieties of cannabis were selectively bred for their sturdy, fibrous stalks. Uncontroversial products like rope and cloth, as well as seeds to press for oil, all came from hemp.

Medical preparations were more likely to use the latin-derived term “cannabis” rather than hemp, even though it was common knowledge that both names referred to the same plant.

Before prohibition, cannabis preparations were used to treat a variety of ailments, including nervousness, melancholy, and headaches. And before smoking became common, there may have been some overlap between recreational and medicinal use.

But recreational smoking, along with the term “marihuana,” became associated with immigrants and the lower class in the early 20th century. Under the new name, it eventually became linked with counterculture movements and illicit drug use.

And because marihuana was the derogatory term used by prohibitionists, it was this term that became enshrined in laws like the Controlled Substances Act.

Hemp vs. Marijuana Today: Chemical and Functional Differences

Scientific advances allowed researchers to identify the substances in cannabis that were responsible for its effects. 

In the 1940s, researchers in Illinois first isolated CBD and THC. Then, in the 1960s, researchers in Israel fully described the molecular structures of CBD, THC, and other cannabinoids. This made it possible to conduct more robust research on both the intoxicating potential and medical benefits of cannabis.

Today, the legal distinction between hemp and marijuana is based solely on THC content. The 2018 Farm Bill defines hemp as any cannabis plant with less than 0.3 percent THC by weight, while marijuana legally is any plant with more than 0.3 percent THC. 

Marijuana may contain a great deal more THC than that, though. In 2017, for example, the most popular strains found in dispensaries in Colorado had a range of THC content from 17 to 28 percent. 

Both “hemp” and “marijuana” varieties are grown for medicinal or therapeutic purposes. That’s because cannabis plants can contain high levels of CBD and other cannabinoids without going over the legal level of THC. Thus, medical hemp is born.

These definitions aren’t without problems. For example, THC potency is not constant over time, and it can spike in response to stress caused by weather conditions. This means that a specific cannabis plant could technically be hemp one day and marijuana the next. The moment the THC level rises above 0.3 percent, the plant is no longer hemp.

These distinctions are more of an issue with plants that are bred for cannabinoid production than those that are grown specifically for fiber or oilseed, though. 

What Do Scientists Say About the Differences Between Hemp and Marijuana?

While cultural forces may shift over time, surely science would offer definitive answers about what constitutes marijuana or hemp. Right? 

The truth is that scientists haven’t completely agreed on how to classify the different varieties of cannabis. And this further complicates the question of what makes marijuana different from hemp.

Since the 1700s, botanists have disagreed about whether cannabis is one species comprising different varieties, or two or more distinct species (most commonly: Cannabis ruderalis, Cannabis indica and Cannabis sativa) within the genus of Cannabis.

While these distinctions may seem esoteric to most CBD or medical marijuana consumers, they are more than just a matter of academic debate. Under the 2018 Farm Bill, Cannabis sativa L. and its subspecies are the only varieties that are allowed under federal law. 

While a budtender in a marijuana dispensary may point you to a cannabis product that bears either a “sativa,” “indica,” or “hybrid” label, botanists are influencing the industry to see the plant in different ways.

For example, one new system proposed by Karl Hillig in 2005 would classify all fiber-producing hemp varieties as one species: Cannabis sativa. This species has tall stalks and narrow leaves, it’s also known as narrow leaf hemp (NLH). All drug varieties, on the other hand, would be classified as members of the species Cannabis indica under this system. Within Cannabis indica, there would be narrow-leaf and broad-leaf drug varieties (NLD and BLD).

This system of classification is complicated by the fact that genetic testing reveals that some drug strains are genetically closer to hemp than other drug strains. Even with their significant differences, hemp and marijuana varieties still share a common genetic pool.

What are sativa and indica strains?

There are distinct varieties of cannabis when you look at physiology, genetics, and human usage. But these different ways of looking don’t always match perfectly.

During the late 20th century, the illicit cannabis trade led to creative cannabis breeding and hybridization in search of more potent psychoactive effects. Certain psychoactive effects became associated with marijuana types called “indica” or “sativa” in the vocabulary of cannabis culture.

In a 2016 interview, psychopharmacology researcher Dr. Ethan Russo weighed in on the sativa/indica debate. His comments reflected the current attitudes of many cannabis researchers and industry professionals. 

“There are biochemically distinct strains of cannabis, but the sativa/indica distinction as commonly applied in the lay literature is total nonsense and an exercise in futility,” Russo said. “One cannot in any way currently guess the biochemical content of a given Cannabis plant based on its height, branching, or leaf morphology.”

He went on to explain that cannabis interbreeding has resulted in such variation that only biochemical analysis can reveal what is really in the plant. 

Are there genetic differences between hemp and marijuana? 

As genetic testing becomes more widespread and affordable, this may seem like an easy way to define and distinguish between marijuana and hemp. And surely it seems that genetic analysis should be able to predict whether a plant will produce enough THC to be legally classified as marijuana.

But once again, it’s just not that easy.

It is true that genetic factors play a significant role in the production of cannabinoids like CBD, THC, and CBG. But cannabinoid content isn’t determined by genes alone.

Cannabis growers often describe differences between cloned plants, and the cannabinoid content of genetically identical plants may vary significantly.

With the recent explosion of hemp agriculture in the US, growers have also found that the selection of hemp plants for low levels of THC has failed to completely remove THC. And environmental factors may play a substantial role. A cannabis cultivar that is reliably low enough in THC to be classified as hemp in one region may produce too much THC when grown in another location.

One day, genetic testing may fulfill its promise to predict cannabinoid expression. Today, though, the complex genetic architecture that determines cannabinoid expression is not yet completely understood.

What do Consumers Need to Know About the Differences Between Hemp and Marijuana?

As we’ve seen, the differences between hemp and marijuana are very much up for debate. And for consumers, that can make it hard to separate good information from bad when shopping for medical marijuana or CBD products.

The key thing to remember is that there is no difference between the cannabinoids themselves when they are derived from hemp or marijuana. CBD is CBD, whether it comes from hemp or marijuana.

That said, the fact is that marijuana varieties have been bred to produce abundant flowers teeming with trichomes and terpenes. This means that marijuana flowers and extracts may naturally contain higher quantities of cannabinoids and terpenes — not to mention other potentially valuable and lesser-known plant compounds. 

Simply put, you can generally get more cannabinoids from marijuana than from hemp. And if you are shopping for CBD but want a high proportion of other cannabinoids, products that comes from “marijuana” plants may be more effective for you.

On the other hand, growers are already developing CBD hemp strains that produce high amounts of cannabinoids and terpenes with very low THC levels. For those who want or need to avoid THC, these products may be superior.

Hemp vs. Marijuana: Legal Issues 

Aside from being able to choose the right products for their needs, consumers should be aware of the legal issues surrounding hemp and marijuana in their state or locality.

The 2018 Farm Bill removed hemp from the Controlled Substances Act, placing it under the regulatory purview of the FDA and USDA.

Those agencies are developing regulations for hemp-derived CBD, but in general terms it is federally legal. That said, a few states have stricter laws controlling the sale and possession of hemp and CBD.

Marijuana, on the other hand, is still listed as a Schedule I substance under the Controlled Substances Act. This places it under the authority of the DEA, and means that it is still illegal under federal law at the time of this writing.

In the last few decades, though, individual states have passed laws making marijuana accessible to many more people. This means that in some states, adults may be able to buy, sell or possess marijuana — or even grow marijuana plants — for their own use. In others, medical marijuana laws enable people with specific medical conditions to benefit from the plant.

As a consumer, it’s important to know the laws that are relevant to you. This will help you to understand whether there are any legal risks associated with purchasing or possessing cannabis products where you live, work, or travel.

Furthermore, cannabis consumers should understand the risks associated with drug testing. Even if adult use of cannabis is legal in your state, you aren’t protected if your employment is contingent on drug testing. Many athletes are also subject to drug testing, and patients at pain clinics may also be tested as part of their treatment.

Even hemp products with non-detectable amounts of THC may contain traces that can build up in your system over time. Many hemp-derived CBD manufacturers advise people who are subject to drug testing to avoid all cannabis products, including their own.

Conclusion: Looking to the Future of Hemp and Marijuana

Shifting definitions of marijuana and hemp show that the distinctions are subjective and cultural, and aren’t always based on objective scientific differences.

In other words, what we call the plant reflects its role in society. When people were worried about intoxication, they adopted a term associated with “drug” use. And when the Controlled Substances Act resulted in the development of an illicit marijuana industry, cannabis terminology arose from the underground market. 

But as attitudes towards cannabis change, so do the words we use to talk about it. Terms like “indica” and “sativa” are falling out of fashion as research illuminates new ways of thinking about cannabis.

And if high-THC varieties of cannabis become legal nationwide, will the distinction between hemp and marijuana still be relevant, or will classifications that more accurately reflect scientific developments become the norm?

Whether it’s classified as marijuana or hemp, the cannabis plant has a remarkable range of uses, and we’re only beginning to understand its potential.