What is Hemp?

The marijuana plant has many uses apart from drug use. A distinct variety of the Cannabis sativa plant, known as hemp, can be grown to maximize the fibers in the stalk of the plant or to maximize seed production. Hemp has a minimal amount — about 1 percent — of the psychotropic chemical THC.

hemp rope
Rope made from hemp fiber.
Credit: Dario Sabljak | Shutterstock

Hemp can grow about 18 feet tall. Hemp fiber from the stalk is similar to flax, the source of linen, and can be used for fabric, rope, paper and even as bedding for animals. Hemp seeds crushed for oil and flour are found in nutrition bars, chips, beer, salad dressing and other foods. Hemp oil is sold by itself as a nutrition supplement. Soaps, shampoos, moisturizers and other body care products contain hemp oil as an ingredient.

Countries that export industrial hemp to the U.S. usually have a strict limit on the percent of THC present in a sample. Anything over 1 percent THC by weight would be considered marijuana. Industrial hemp usually has less than 0.3 percent THC by weight, according to the U.S. Department of Agriculture. Marijuana grown for drugs typically has 3 to 15 percent THC by weight. 

hemp seed
Hemp seeds can be made into flour, or added to chips, beer and salad dressing.
Credit: JGade | Shutterstock

Federal law prohibits farmers from growing both marijuana and industrial hemp. But hemp products are legal in the United States. Companies that use hemp as an ingredient can legally import hemp. Bills supporting local industrial hemp in several states have aimed to undercut federal restrictions on farming.

But these bills, lawsuits, protests and formal petitions to the White House in recent years haven't changed the current federal law. In response to a formal petition to allow industrial hemp farming, a representative from the Obama administration wrote, “While most of the THC in cannabis plants is concentrated in the marijuana, all parts of the plant, including hemp, can contain THC, a Schedule I controlled substance.”

History of hemp

Some of the earliest records of people growing hemp come out of China in 2700 B.C. By the 16th century, Europeans were using hemp for food and textiles. Puritans brought hemp with them to New England in 1645, and the plant was grown even earlier than that in Chile. George Washington planted hemp at Mount Vernon, but cheaper textiles eventually pushed out hemp as a major crop in the United States.

There is an urban legend that the U.S. Constitution, the Bill of Rights and the Declaration of Independence were written on hemp paper. This is not entirely true. The documents housed in the National Archives were written on parchment, which is treated animal skin, typically sheepskin. However, it is likely that the drafts of the documents were written on hemp paper, because most paper at the time was made from hemp.

Hemp production in the United States saw a brief boom in the mid-1800s when the U.S. Navy was in high demand for the material to make ropes and sails. During World War II, the lack of available abaca and jute prompted the government to start pro-hemp farming campaigns to meet the Navy's demand for rope. Hemp demand fell after WWII and government restriction on the plant resumed.


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Lauren Cox

Lauren Cox

Lauren Cox is a contributing writer for Live Science. She writes health and technology features, covers emerging science and specializes in news of the weird. Her work has previously appeared online at ABC News, Technology Review and Popular Mechanics. Lauren loves molecules, literature, black coffee, big dogs and climbing up mountains in her spare time. She earned a bachelor of arts degree from Smith College and a master of science degree in science journalism from Boston University.
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