Hemp

• Scientific name: Cannabis sativa
• Family: Cannabaceae
• Also known as: Marijuana, Ganja, Weed

Coarse, bushy herb up to 4m tall. Leaves grey-green, up to 12cm long, palmate with 3-9 lanceolate leaflets, margin serrated. Individual plants either have male or female flowers (dioecious). Flowers small, green and clustered. Fruits small, dry and thin-walled (achene), contain only one seed. Pollinated by wind

Did you know?

One of the oldest relics of human industry is a bit of hemp fabric dating back to approximately 8,000 BC.

• Hemp grows fast, is very adaptable to soil and climatic conditions and is undemanding on resources such as artificial fertilisers and pesticides. It provides a good break crop for the farmer, giving the land a rest from other crops and helping to prevent disease.
• It is a potential flagship sustainable crop for the 21st century, but there's a reason why our fields aren’t full of it. It produces a substance that became socially controversial in the early part of the 20th century: tetrahydrocannabinol (THC), which as well as having many medicinal attributes has been used as a recreational drug. In recent years breeding and selection has resulted in cultivars low in THC, and hemp is once again being considered by governments as a useful crop.
• Hemp is six times as strong as cotton, much more resistant to weathering and wear, and more lustrous and absorbent. It is also much more environmentally friendly to grow.
• In the 16th century Henry VIII made hemp cultivation obligatory. He was interested in it for making rope – very important, especially to ships in those days.

For centuries hemp has provided raw materials for paper, textiles, rope for ships, medicine, oil and much more. It is one of the most useful multi-purpose crops of the temperate world quoted as having over 25,000 end products. For example, the seed can be used as a food protein and the outer stem provides fibre for ropes and canvas for tents. It is illegal in most countries because the leaves of the high-THC types can be dried and smoked to provide a mild narcotic.

The fibre crop grown in Europe has no THC and mostly supplies the specialist paper industry and the non-woven converting industry, which supplies automotive companies.

• Hemp items in the Victoria and Albert Museum

Glossary

• Lanceolate: narrowly ovate and tapering to a point.
• Palmate: when all lobes originate from a central point (lobes are incomplete divisions in the leaves).
• Scabrous: rough to the touch.