views updated Jun 11 2018


Cannabis sativa (of the family Cannabaceae) is the Latin name for marijuana and hemp. The cannabis plant has been cultivated and used for many centuries by a variety of cultures, primarily for two distinct purposes. The long, tough fibers of the stem have been (and still are) used for making rope and cloth (hemp). The leaves and flowers produce a resin (marijuana) that has been (and still is) smoked to attain an altered state of consciousness. In the United States and many other countries, possession and use of marijuana is against the law under most circumstances, although a number of changes in these laws have recently been made to allow it to be used for medical treatment in some states.

Cannabis grows as a woody annual plant. It favors deep, well-drained, loamy soils, but can, and does, grow in almost any soil. The fibers of the stem are formed from tough sclerenchyma cells, joined together to make long strands. The leaves are compound, with five to seven serrated leaflets arranged palmately in a fan shape. The flowers, which form at the end of the summer, are separated by sex onto different plants. Full-grown plants can attain a height of ten feet or more, and a breadth of several feet, but when planted for fiber, seeds are sown so thickly that little branching occurs and stems remain very thin.

To harvest the fibers, the plants are cut before flowering and left to cure for days to weeks in the field. This allows retting, or rotting of the stem to loosen the fibers. The fiber is extracted by macerating the plant in water and removing the pulp. Hemp fibers, each from three to six feet long, can be corded into a strong and durable rope. Historically, hemp rope pulled the water bucket from the village well, hanged the criminal on the gallows, and outfitted the great sailing ships of the voyages of discovery. Cannabis varieties grown for hemp contain extremely low levels of psychoactive substances. Despite this, hemp went largely out of use as a fiber source in the United States during the mid-twentieth century, due mainly to the political difficulties of keeping it in production while marijuana as a drug was being outlawed.

Leaves and flowers are harvested and dried before the plant reaches full maturity, and most commonly before the seeds have set. Female flowers contain more of the active ingredient THC (delta-tetrahydrocannabinol) than either the male flowers or the leaves, and the THC content decreases after fertilization. Because of this, male plants are often removed from stands being grown for their THC. This simultaneously increases the soil nutrients available to the female plants and prevents fertilization of the flowers.

Late in the twentieth century in the United States, the legal use of marijuana has been promoted because of its potential for treating several medical conditions, including glaucoma (high fluid pressure within the eye), spasticity , and nausea during chemotherapy. Several states, most notably California, have passed "compassionate use" laws that allow patients to legally obtain marijuana for smoking. At the same time, several states are moving forward with legislation to allow fiber hemp to be grown legally, though these efforts will require the cooperation of the U.S. Drug Enforcement Administration. Currently, hemp fiber for use in the United States is imported from Canada, China, and several other countries where it is grown legally.

see also Cultivar; Defenses, Chemical; Fiber and Fiber Products; Psychoactive Plants.

Richard Robinson


Clarke, Robert C. Marijuana Botany, 2nd ed. Berkeley, CA: Ronin Publishing, 1992.


views updated May 17 2018

can·na·bis / ˈkanəbəs/ • n. a plant (Cannabis sativa, family Cannabaceae) used to produce hemp fiber and as a mildly psychotropic drug. Also called hemp, marijuana. ∎  a dried preparation of the flowering tops or other parts of this plant, or a resinous extract of it (cannabis resin).


views updated May 21 2018

cannabis Common name for the Indian hemp plant, Cannabis sativa (family Cannabidaceae), and for the dried plant or extracted resin when used as a psychotropic drug. The drug produces narcotic effect sometimes allied with a feeling of well-being. It is highly carcinogenic and can induce mild psychosis. It has been shown to relieve the symptoms of some illnesses, such as multiple sclerosis.


views updated May 14 2018

Cannabis (family Cannabidaceae) A monotypic genus comprising C. sativa (hashish, hemp, ganja, marijuana) which is native to central Asia. It is a large herb that provides a narcotic as well as hemp fibre.


views updated Jun 27 2018

cannabis (kan-ă-bis) n. a drug prepared from the Indian hemp plant (Cannabis sativa), also known as pot, marijuana, hashish, and bhang. It produces euphoria and hallucinations and has little therapeutic value; its nonmedical use is illegal. See also dependence.