Is it hemp, cannabis or marijuana?
That depends on who's discussing the enigmatic plant that's legal in some forms (for now) but faces new restrictions in other forms this fall.
The confusion comes as no surprise to Nick Johnson, author of the book Grass Roots, which looks at the history of the cannabis plant and its use as both an industrial material and a drug.
"It's one of the world's oldest domesticated crops," Johnson says of cannabis. "And it's also incredibly cryptic. We still do not understand everything about its biology and why it does the things it does, how it creates the compounds and molecules it does."
Cannabis "has over 480 constituents," according to the Drug Enforcement Administration, but U.S. regulators focus on just one: THC, the compound linked to the drug's famous psychoactive effects.
Federal laws define legal hemp differently from illegal marijuana based on their levels of THC. As long as a plant contains less than 0.3% of one form of THC (with a much stricter limit taking effect later this year), it's considered hemp, not marijuana. And while marijuana is in the process of being reclassified as a Schedule III drug instead of a more restricted Schedule I, hemp is not a controlled substance.
Despite the different policies, qualities and uses, the plants are more similar than not.
"Botanically speaking, both hemp and marijuana belong to a single species: Cannabis sativa," says Kelly Vining, an associate professor at Oregon State University who studies hemp genomics. In general, Vining says, taxonomists consider hemp and marijuana subspecies of Cannabis sativa.
But legal definitions of hemp are in hot dispute, in Congress and around the United States. A new federal law will sharply limit the amount of THC (and similar compounds) in final products rather than focusing on plants — aiming to close a loophole in the 2018 Farm Bill that spawned a multibillion-dollar industry in intoxicating drinks.
Critics say this new law should be revised, warning of calamitous effects on THC drink makers and businesses that use other cannabinoids — compounds found in cannabis — such as CBD, or cannabidiol.
The shifting definitions are just the latest twists for hemp, a former cash crop that was later banned. Here's a brief guide to its history:
Hemp was once an important U.S. crop
A staple crop in Colonial and early America, hemp was used to produce everything from the ropes and sails used on ships to the clothes enslaved people wore, as well as the twine for baling the cotton and other commodities they produced.
"Hemp was cultivated in New England as early as 1629," according to a history of hemp published by S.S. Boyce in 1900.
Colonies such as Virginia rewarded farmers for growing hemp and penalized farmers who didn't, he noted.
There was one thing hemp was not used for, says Johnson, the author of Grass Roots.
"Nobody was smoking weed in George Washington's time," he says, aiming to clear up a common misconception. "They grew hemp. They didn't smoke it — they didn't drink it. They didn't use it at all for psychoactive purposes."
The origin of "drug cannabis"
Indigenous people in North America and South America did not use cannabis as a drug before colonizers such as Britain and Spain introduced those forms of the plant, according to Johnson. Varieties of the plant bred for mind-altering uses started far earlier and on another continent: in the Hindu Kush mountains of Afghanistan.
Compared with the towering hemp plant that was prized for its long and strong fibers, this Asian version of cannabis was short and squat and was prized for other reasons. To protect itself from sunlight's intense radiation at high altitude, Johnson says, the plant evolved a "sunscreen" for its flowers: the THC resin that coats the buds.
The British encountered the plant in India, where locals had cultivated cannabis for psychoactive purposes for thousands of years. The cultivar's spread to the Western Hemisphere got a boost from what might seem like an unlikely event: When Britain abolished slavery in the Caribbean in 1834, it brought indentured Indian laborers to work at Caribbean plantations.
"You start having the free or formerly enslaved Black populations mixing with the new indentured servant populations," Johnson says. "The Rastafarian tradition has its roots there."
The new variety of cannabis spread to the mainland, along with its status as a drug or medicine for pain relief and other uses. By 1851, a cannabis extract was listed in the Pharmacopoeia of the United States, a reference used by physicians and pharmacists.
Despite their distinct evolutions, cannabis plants use one mechanism to create much discussed cannabinoids such as THC and CBD, horticulture professor Vining says.
"They're both synthesized by the same biosynthetic pathway" in plants, she says. "There are different enzymes that convert precursor molecules into the downstream molecules that are cannabinoids, including THC and CBD."
But not every cannabis plant can produce high levels of those cannabinoids. Farmers have bred hemp for centuries, Vining notes, selecting plants that offer large size and strong fibers — not THC or other cannabinoids.
The start of a U.S. crackdown on cannabis
The first widely recorded U.S. ban on cannabis came in 1915, in El Paso, Texas, despite the concern of doctors and pharmacists who cited its medicinal use. The El Paso Herald newspaper reported, "It is put up by the foremost drug manufacturers in the country and is frequently prescribed, as it is a sedative of value."
Federal regulation of cannabis started with the Marihuana Tax Act of 1937, mirroring a shift in terminology from "cannabis" to "marijuana" that is widely attributed to authorities' goals of linking cannabis to racial and ethnic groups by depicting marijuana as a scourge among Mexicans and Black people.
Even tighter U.S. restrictions on cannabis came in the early 1970s, when President Richard Nixon approved adding it to the list of Schedule I drugs, such as heroin, that have no accepted medical use and a high potential for abuse.
Nixon did so "over the unanimous recommendation of his drug commission that called for decriminalization," as NPR's Cokie Roberts reported in 2019. "Later, his aide, John Ehrlichman, said Nixon wanted to get at pot-smoking, anti-war protesters and to disrupt Black neighborhoods with criminalization."
While other Schedule I drugs are known to carry fatal risks due to overdose, the Drug Enforcement Administration says, "No deaths from overdose of marijuana have been reported."
A new U.S. hemp definition is on the way
As President Trump's rescheduling order suggests, public opinion on marijuana has softened across political lines since the 1970s. Many states have legalized recreational or medicinal pot, and cannabinoids such as CBD have gained recognition from the Food and Drug Administration and others for their therapeutic properties. But researchers have said the federal marijuana ban makes it difficult to study the potential health risks and benefits, even as its use spreads.
The 2018 Farm Bill was an emblem of that shifting conversation, as politicians sought to differentiate between hemp and marijuana. Those changes also give lawmakers political cover to discuss easing regulations, says Adam Smith, the executive director of the Marijuana Policy Project, a legalization advocacy group.
"We're not really in favor of marijuana, but we're not going to stop this other thing that's different," Smith says of the political calculus. "But it's not different, right? It's all cannabinoids."
The new, more restrictive rules regulating cannabis — and defining hemp — are scheduled to go into effect in November. At that point, a final product that contains more than 0.4 milligrams of any form of THC or "any other cannabinoids that have similar effects" will not be considered hemp — and thus will be illegal.
Hemp beverage companies, which have built an increasingly mainstream market since the 2018 Farm Bill allowed for some hemp-derived THC products, say the change would ban drinks currently on the market that are considered low or moderate strength, from 2 to 10 milligrams of THC per container. And other hemp companies say the new law will also effectively ban some products with nonintoxicating cannabinoids like CBD if they have trace amounts of THC.
Aside from the THC debate, Vining of Oregon State University says that easing rules on hemp has helped clear the way to study more uses for the plant, from its nutritious seeds to its fibers, which can be used in "hempcrete," a building material.
"There are many uses beyond drug use for Cannabis sativa," she says. "And they've been used throughout human history."
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