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Cannabis sativa L.

Syn.: Cannabis indica Lam.
Hemp, Marijuana, Cannabis oil

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.

  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Toxicity
  5. Description
  6. Germplasm
  7. Distribution
  8. Ecology
  9. Cultivation
  10. Harvesting
  11. Yields and Economics
  12. Energy
  13. Biotic Factors
  14. References


A multiple-use plant, furnishing fiber, oil, medicine, and narcotics. Fibers are best produced from male plants. In the temperate zone, oil is produced from females which have been left to stand after the fiber-producing males have been harvested. Leaves are added to soups in southeast Asia. Varnish is made from the pressed seeds. Three types of narcotics are produced: hashish (bhang), the dried leaves and flowers of male and female shoots; ganja, dried unfertilized inflorescences of special female plants; and charas, the crude resin, which is probably the strongest. Modern medicine uses cannabis in glaucoma and alleviating the pains of cancer and chemotherapy. More resin is produced in tropical than in temperate climates. Lewis lung adenocarcinonoma growth has been retarded by oral administration of delta-9-tetrahydrocannabinol, delta-8-tetrahydrocannabinol and cannabinol, but not by cannabidiol. (J.N.C.I. 55: 597-602. 1975). The delta-9 also inhibits the replication of Herpes simplex virus.

Folk Medicine

Medicinally, plants are tonic, intoxicant, stomachic, antispasmodic, analgesic, narcotic, sedative and anodyne. Seeds and leaves are used to treat old cancer and scirrhous tumors. The seed, either as a paste or as an unguent, is said to be a folk remedy for tumors and cancerous ulcers. The decoction of the root is said help remedy hard tumors and knots in the joints. The leaf, prepared in various manners, is said to alleviate cancerous sores, scirrhous tumors, cold tumors, and white tumors. The plant is also used for mammary tumors and corns (C.S.I.R., 1948-1976). Europeans are said to use the dregs from Cannabis pipes in "cancer cures" (Watt and Breyer-Brandwijk, 1962). Few plants have a greater array of folk medicine uses: alcohol withdrawal, anthrax, asthma, blood poisoning, bronchitis, burns, catarrh, childbirth, convulsions, coughs, cystitis, delirium, depression, diarrhea, dysentery, dysmenorrhea, epilepsy, fever, gonorrhea, gout, inflammation, insomnia, jaundice, lockjaw, malaria, mania, mennorhagia, migraine, morphine withdrawal, neuralgia, palsy, rheumatism, scalds, snakebite, swellings, tetany, toothache, uteral prolapse, and whooping cough. Seeds ground and mixed with porridge given to weaning children.


Most varieties contain cannabinol and cannabinin; Egyptian variety contains cannabidine, cannabol and cannabinol, their biological activity being due to the alcohols and phenolic compounds. Resin contains crystalline compound cannin. Alcoholic extracts of American variety vary considerably in physiological activity. Per 100 g, the seed is reported to contain 8.8 g H2O, 21.5 g protein, 30.4 g fat, 34.7 g total carbohydrate, 18.8 g fiber, and 4.6 g ash. In Asia, per 100 g, the seed is reported to contain 421 calories, 13.6 g H2O, 27.1 g protein, 25.6 g fat, 27.6 g total carbohydrate, 20.3 g fiber, 6.1 g ash, 120 mg Ca, 970 mg P, 12.0 mg Fe, 5 mg beta-carotene equivalent, 0.32 mg thiamine, 0.17 mg riboflavin, and 2.1 mg niacin. A crystalline globulin has been isolated from defatted meal. It contains 3.8% glycocol, 3.6 alanine, 20.9 valine and leucine, 2.4 phenylalanine, 2.1 tyrosine, 0.3 serine, 0.2 cystine, 4.1 proline, 2.0 oxyproline, 4.5 aspartic acid, 18.7 glutamic acid, 14.4 tryptophane and arginine, 1.7 lysine, and 2.4% histidine. Oil from the seeds contains 15% oleic, 70% linoleic, and 15% linolenic and isolinolenic acids. The seed cake contains 10.8% water, 10.2% fat, 30.8% protein, 40.6% N-free extract, and 7.7% ash (20.3% K2O; 0.8% Na2O; 23.6% CaO, 5.7% MgO, 1.0% Fe2O3, 36.5% P2O5, 0.2% SO3; 11.9% SiO2, 0.1% Cl and a trace of Mn2O3). Trigonelline occurs in the seed. Cannabis also contains choline, eugenol, guaiacol, nicotine, and piperidine (C.S.I.R., 1948-1976), all listed as toxins by the National Institute of Occupational Safety and Health. A beta-resercyclic acid derivative has antibiotic and sedative properties; with a murine LD56 of 500 mg/kg, it has some aritiviral effect and inhibits the growth of mouse mammary tumor in egg embryo (Watt and Breyer-Brandwijk, 1962).


Non-users may suffer muscular incoordination (9 of 22 persons), dizziness (8), difficulty concentrating (8), confusion (7), difficulty walking (7), dysarthria (7), dry mouth (7), dysphagia (5), blurred vision (5), and vomiting (1), following oral ingestion of THC disguised in cookies (MMWR, October 20, 1978). People working with the plant or the fiber may develop dermatitis. In larger doses, hemp drugs may induce catalepsy, followed by coma and DEATH from cardiac failure (C.S.I.R., 1948-1976).


Annual herb, usually erect; stems variable, up to 5 m tall, with resinous pubescence, angular, sometimes hollow, especially above the first pairs of true leaves; basal leaves opposite, the upper leaves alternate, stipulate, long petiolate, palmate, with 3-11, rarely single, lanceolate, serrate, acuminate leaflets up to 10 cm long, 1.5 cm broad; flowers monoecious or dioecious, the male in axillary and terminal panicles, apetalous, with 5 yellowish petals and 5 poricidal stamens; the female flowers germinate in the axils and terminally, with one 1-ovulate ovary; fruit a brown, shining achene, variously marked or plain, tightly embracing the seed with its fleshy endosperm and curved embryo. Fl. summer; fr. late summer to early fall; year round in tropics. Seeds weigh 1.5-2.5 gm/100 seeds.


As Cannabis sativa has been cultivated for over 4,500 years for different purposes, many varieties and cultivars have been selected for specific purposes, as fiber, oil or narcotics. Drug-producing selections grow better and produce more drug in the tropics; oil and fiber producing plants thrive better in the temperate and subtropical areas. Many of the cultivars and varieties have been named as to the locality where it is grown mainly. However, all so called varieties freely interbreed and produce various combinations of the characters. The form of the plant and the yield of fiber from it vary according to climate and particular variety. Varieties cultivated particularly for their fibers have long stalks, branch very little, and yield only small quantities of seed. Varieties which are grown for the oil from their seed are short in height, mature early and produce large quantities of seed. Varieties grown for the drugs are short, much-branched with smaller dark-green leaves. Between these three main types of plants are numerous varieties which differ from the main one in height, extent of branching and other characteristics. Reported from the Central Asia, Hindustani, and Eurosiberian Centers of Diversity, marijuana or cvs thereof is reported to tolerate disease, drought, fungus, high pH, insects, laterite, low pH, mycobacteria, poor soil, slope, and weeds. (2n = 20, 10, 40.)


Native to Central Asia, and long cultivated in Asia, Europe, and China. Now a widespread tropical, temperate and subarctic cultivar and waif. The oldest use of hemp seems to be for fiber, and later the seeds began to be used for culinary purposes. Plants yielding the drug seem to have been discovered in India, cultivated for medicinal purposes as early as 900 BC. In medieval times it was brought to North Africa where today it is cultivated exclusively for hashish or kif.


Plants very adaptable to soil and climatic conditions. Hemp for fiber requires a mild temperate climate with at least 67 cm annual rainfall, with abundant rain while seeds are germinating and until young plants become established. Thrives on rich, fertile, neutral to slightly alkaline, well-drained silt or clay loams with moisture retentive subsoils; does not grow well on acid, sandy soils. Of the many types of hemp, some are adapted to most vegetated terrains and climates. Ranging from Cool Temperate Steppe to Wet through Tropical Very Dry to Wet Forest Life Zones, marijuana is reported to tolerate annual precipitation of 3 to 40 dm (mean of 44 cases = 9.9 dm), annual temperature of 6 to 27°C (mean of 44 cases = 14.4), and pH of 4.5 to 8.2 (mean of 38 cases 6.5) (Duke, 1978, 1979).


Propagation mainly by seed. Experimentally, drug plants have been propagated from cuttings but such plants do not come true as to drug content of parent. Seeds stored in cool, dry place remain viable for up to two years. Hemp seed sown as early in spring as possible. Before sowing, land is plowed (in fall) several times to a depth of about 20-23 cm and repeatedly harrowed the land. In spring the land is harrowed again and rolled, making a firm tilth over the entire surface. In some areas a first plowing is done in the fall and red clover or lupin planted; in January or February a second plowing turns these under as a green-manure. Generally sown in March, seeds germinate at low temperature, but not below 1deg.C. Rate of seed sown varies with type of fiber desired; for coarse fiber for cordage and coarser textiles, 2.5 bu/ha is used; for finest fibers, 7.5-10 bu/ha used. Seed sown by machine in rows from 12 cm upwards, placing the seed at depth of 3.5 cm at rate of 40-60 kg/ha. In many countries seed sown broadcast. When grown for seed (oil), seed sown by drills; then such plants sometimes reach height of 5.3 m with thick stems up to 5 cm in diameter, much-branched. For fiber, stems up to 2 m tall and 0.5 cm in diameter are best; larger stems tend to get woody and have lower fiber content. Besides, they are more difficult to handle during harvesting, retting and scutching. Plants require little cultivation, except for weeding during early stages of growth. Hemp grows rapidly and soon crowds out weeds. After plants are 20 cm tall, weeding is abandoned. Hemp tends to exhaust the soil of nutrients. Some nutrients are returned to the soil after plants are harvested. On medium fertile soils a dressing of farm manure or a green-manure crop should be added and turned under. Chalk, potash, or gypsum may be applied to the soil to add the needed nutrition. Sodium nitrate and ammonium along with potassium sulfate have a beneficial effect on the fiber crop. Fiber-producing plants should always have plenty of proper nutrients, especially nitrogen, which is the most important element needed. Irrigation is seldom practiced.


Hemp is ready for harvest four to five months after planting, rarely earlier for some varieties. Harvesting depends on the climatic conditions, the variety of hemp grown and whether the crop is being grown for hemp or seed. In temperate areas, hemp is usually harvested from mid July to mid August. Both male and female plants look alike until they flower; then the male plants turn yellow and die, whereas the female plants remain dark green for another month until the seed ripens. Male plants are ready to harvest for fiber when the leaves change from dark green to light brown. The best yield of fiber (and only male plants are used) is then obtained. Hemp is harvested when the staminate flowers are beginning to open and shed their pollen. Seed is harvested from the female plants when most of it falls off when the plant is shaken. Best time of day to harvest seed is in early morning when fruits are turgid and conditions damp. As fruits dry out by mid-day, seed loss increases due to shattering. Usually stems are cut and the seeds shaken out over canvas sheets or beaten with sticks to extract the seeds. For fiber, hemp plants are cut by hand with a hemp knife, similar to a long-handled sickle. Plants are cut 2-3 cm above the ground and spread on the ground to dry. In some areas, the entire plants are pulled up and laid out to dry. Hand cutting, one man can cut about one-fifth hectare per day. Sometimes specially designed harvesters with a tractor are able to harvest four hectares a day. In many areas several varieties of hemp are grown so as to spread out the harvest, one maturing in late July and used later for seed crop in September, a second crop maturing in mid August, and a third maturing near end of August. Fiber is extracted from the stems of hemp by retting by methods similar to those used for other fiber plants. Sometimes the stems are dried before they are retted. After plants have air-dried for 4-6 days, the root and flower ends are cut off and the remaining portions, with branches and leaves taken or beaten off, are made into small bundles. For retting, 15-20 of these smaller bundles are made into larger bundles. In other areas stalks are not dried before retting, green stems, after roots and flower ends have been cut off, are made into bundles, and retted immediately. Hemp can be water retted, dew retted, or snow retted, according to the climatic conditions. The retted hemp stalks consist of fiber in the outer rind and a woody interior portion. Fiber is separated from the stalk by a breaking process. Stalks are dried after retting and the woody shive is broken into short pieces called hurds. Eventually the fibers are separated from the interior woody pieces by scutching by passing the bundles through a number of fluted rollers and then past large revolving drums with projecting bars which remove any remaining pieces of wood. Machines are able to handle 3-3.5 MT dried straw every hour, producing 0.4-0.5 MT of cleaned fiber.

Yields and Economics

Yields of hemp per hectare depend on climatic conditions, variety grown, soil and nutrition, and spacing of plants in the field. Weight of dried stems per hectare is usually between 4.5 to 7.5 T, with a yield of fiber about 25% of the dried stalks. Usually the taller the plant, the longer will be the fiber with a greater yield per plant. In some areas fiber yields of 850- 1,700 kg/ha compared to 1,300-1,700 kg/ha seed and 30 kg ganja. The U.S.S.R. is the largest producer of hemp in the world, producing about 33% of hemp fiber, annually 105,000 MT compared to the world production of 255,000 MT (excepting China). France and West Germany are the chief importers, Italy and Yugoslavia exporters. Chile, China, Japan and Peru also produce hemp. Narcotic production is usually clandestine, but there is legal marijuana production in India. India is the main producer and exporter of oil from the seed.


In India, plants remaining in the field after harvesting for fiber are allowed to set seed. They are cut after the fruits are ripened and dried and threshed for seed collection. Grown solely for seeds, an average crop yields 1.3 to 1.6 MT/ha seed. The world low production yield was 288 kg/ha in Democratic People's Republic of Korea, the international production yield was 613 kg/ha, and the world high production yield was 3,842 kg/ha in People's Republic of China.

Biotic Factors

Among diseases of Cannibis are: Botryosphaeria marconii (stem canker, wilt), Botrytis cinerea (gray mold), Cylindrosporium sp. (leaf spot), Fusarium sp. (canker, stem rot), Gibberella saubinetii (stem rot), Hypomyces cancri (?root rot), Macrophominia phaseoli, Phomopsis cannabina, Phymatotrichum omivorum (root rot), Sclerotinia sclerotiorum (stem rot, wilt), Sclerotium rolfsii (southern blight), Septoria cannabis (leaf spot). Nematodes include: Ditylenchus dipsaci, Heterodera humuli, Longidorus maximus, Meloidogyne hapla, M. incognita, M. incognita acrita, M. spp., and Pratylenchus coffeae (Golden, p.c., 1984). Occasionally Orobanche ramosa is paratitic on the roots.


Complete list of references for Duke, Handbook of Energy Crops
Last update July 3, 1996