Industrial hemp- sometimes referred to as hemp- is the cannabis sativa L. plant when it contains 0.3% tetrahyrdocannabinol (THC) or less. Hemp belongs to the Cannabaceae family, containing over 270 species, and is often confused with cannabis plants that are used as a source of the drug marijuana. However, industrial hemp does not have any psychoactive properties and is identified as an agricultural crop. In this section you will find the history and plant anatomy of hemp including antibacterial properties.
Hemp originated in Central Asia, and was cultivated as early as 2800 BCE. Making it's way through Europe in the Middle Ages and North America in the early 16th century, settlers often used hemp for rope, textiles, and oil applications. In the early 20th century, hemp was widely used for paper and textiles. In 1937, the United States Government passed the Marihuana Tax Act, criminalizing marijuana and any plant in the cannabis plant family. Despite this, the bill was temporary lifted and government urged farmers to grow hemp to aid during the second World War.
For the next 60 years, hemp was considered an illegal crop in North America. In 1998, the Canadian Government once again allowed the cultivation of industrial hemp and in 2018, the US Farm Bill was passed making hemp federally legal in the United States once again. Learn more on Hemp Legislation in Canada & the United States.
A hemp plant consists of five (5) main components; stalk, root, leaves, seeds and flower. The hemp stalk is tall, dense and strong with the capability of reaching over ten (10) feet tall. The stalk is composed of two layers, the inner layer known as hurd or shiv and the outer layer know as bast fiber. At the top of the stalk are the hemp flowers, where the seeds, bud leaves, and sugar leaves are found. The stalk contains larger leaves known as fan leaves. Learn more about the many uses of hemp.
Hurd & Fiber
Hemp stalk has a short brittle wood-like fiber core called hurd (shiv). Hurd is primarily used for insulation and cellulose purposes. The outer layer of hemp stalk has structural long flexible fibers called bast fiber, which is used for composites, textiles and rope purposes among others. Most hemp-based technical reinforcement fiber is manufactured from bast fiber, while various types of non-structural fiber, absorptive products and functional fillers are made from hurd.
Hemp seeds are on average 1-3 millimeters in size and can be roasted, pressed, and eaten raw. Hemp seeds are used for food and oil purposes. Hemp oil is obtained from the seeds by pressing the seeds and is used to make industrial fluids, food oils, personal care products, and biofuel.
Hemp leaves are palmate shaped and have approximately 3-9 long and slender leaflets. The leaves have a jagged appearance and range in coloration from bright lime green to dark green. Hemp leaves are often used for pharmaceutical and tea purposes.
The flowers on a hemp plant are small greenish-yellow flowers. Hemp plants have seed-producing and pollen-producing flowers. Seed-producing flowers are female and grow in a dense spike cluster at the top of the stalk. While pollen-producing flowers are male and grow in dense branched cluster. Hemp flowers are primarily used for pharmaceutical purposes.
Hemp has been shown to possess antibacterial properties against a range of pathogenic bacteria, including B. subtilis, S. aureua and E.coli. These properties are contributed from cannabinoids, alkaloids, and other bioactive compounds of the hemp plant.
Hemp hurd, the woody core of the hemp stalk, has a high lignin content of 19-21% as well as high hemicelluloses content of 31-37%. In a series of test, it has been found that hurd has strong antibacterial properties against E. coli, bacteria found to infect the lower intestine, and the ability to restrain the growth of micro-organisms such as S. cerevisiae, B. licheniformis, and A. niger.
Additionally, the hemp stalk has also been found to have antibacterial properties against B. subtilis, bacteria that commonly infects the gastrointestinal tract, as well as S. aureus, bacteria that infects the nose, on the skin and in the respiratory tract. Furthermore, the stems and leaves of the hemp plant have also been found to have excellent antimicrobial properties against S. aureus. While hemp has antibacterial and antimicrobial properties it does not, however, have anti-fungal properties.
Khan, B. A.; Warner, P.; Wang, H. Antibacterial Properties of Hemp and Other Natural Fibre Plants: A Review. Bio Resour. 2014, 9 (2), 3642–3659.