|
|
|
|
Cannabis sativa
|
| |
|
| |
Cannabis sativa is an annual plant in the Cannabaceae family. It is a herb that has been used throughout recorded history by humans as a source of fiber, for its seed oil, as food (see hemp), as a drug (see cannabis (drug)), as medicine (see medical cannabis), and for spiritual purposes (see spiritual use of cannabis). Different parts of the plant have different uses, and different varieties are cultivated in different ways and harvested at different times, depending on the purpose for which it is grown.
following taxonomic treatment of Cannabis was published in 1976 by Ernest Small and Arthur Cronquist.
Discussion
Ask a question about 'Cannabis sativa' Start a new discussion about 'Cannabis sativa' Answer questions from other users |
Recent Posts
Encyclopedia
Cannabis sativa is an annual plant in the Cannabaceae family. It is a herb that has been used throughout recorded history by humans as a source of fiber, for its seed oil, as food (see hemp), as a drug (see cannabis (drug)), as medicine (see medical cannabis), and for spiritual purposes (see spiritual use of cannabis). Different parts of the plant have different uses, and different varieties are cultivated in different ways and harvested at different times, depending on the purpose for which it is grown.
Species, subspecies, and varieties
The following taxonomic treatment of Cannabis was published in 1976 by Ernest Small and Arthur Cronquist. Other taxonomic treatments of Cannabis are equally valid, and utilized by some botanists.
- Cannabis
Cannabis sativa L.
C. sativa subsp. sativa
C. sativa subsp. sativa var. sativa
C. sativa subsp. sativa var. spontanea
C. sativa subsp. indica
C. sativa subsp. indica var. indica
C. sativa subsp. indica var. kafiristanica
C. sativa subsp. indica
C. sativa subsp. indica var. kafiristanica
Correct name: Cannabis sativa L. subsp. indica (Lam.) Small & Cronq. var. kafiristanica (Vavilov) Small & Cronq.
Synonym: C. indica Lam. var. kafiristanica Vavilov.
This taxon includes wild or feral plants, mostly confined to the Indian subcontinent and other regions where Cannabis is grown for drug use and has escaped from cultivation. Individual plants may have low, similar, or high levels of THC relative to CBD. Plants with relatively high levels of ?9-tetrahydrocannabidivarin (THCV) and/or cannabidivarin (CBDV) are also common in this group. Compared with wild or feral plants of var. spontanea, plants of this taxon are often taller and more branched. The achenes are usually very small. The inflorescenses of pistillate plants are often elongated, and the fruits (achenes) drop off the plants as they mature.
Common uses
The tough fiber of the plant, cultivated as hemp, has numerous textile uses. Its seed, chiefly used as caged-bird feed, is a valuable source of protein. The flowers (and to a lesser extent the leaves, stems, and seeds) contain psychoactive and physiologically active chemical compounds known as cannabinoids that are consumed for recreational, medicinal, and spiritual purposes. When so used, preparations of flowers (marijuana) and leaves and preparations derived from resinous extract (hashish) are consumed by smoking, vaporizing and oral ingestion. Historically, tinctures, teas, and ointments have also been common preparations.
Plant physiology
Cannabis reproduces sexually. The flowers of the female plant are arranged in racemes and can produce hundreds of seeds. Male plants shed their pollen and die several weeks prior to seed ripening on the female plants. Although genetic factors dispose a plant to become male or female, environmental factors including the diurnal light cycle can alter sexual expression. Naturally occurring monoecious plants, with both male and female parts, are either sterile or fertile but artificially induced "hermaphrodites" (a commonly used misnomer) can have fully functional reproductive organs. "Feminized" seed sold by many commercial seed suppliers are derived from artificially "hermaphrodytic" females that lack the male gene, or by treating the seeds with hormones or silver thiosulfate.
A Cannabis plant in the vegetative growth phase of its life requires more than 12-13 hours of light per day to stay vegetative. Flowering usually occurs when darkness equals at least 12 hours per day. The flowering cycle can last anywhere between five to ten weeks, depending on the strain and environmental conditions.
In soil, the optimum pH for the plant is 6.5 to 7.2. In hydroponic growing, the nutrient solution is best at 5.2 to 5.8, making Cannabis well-suited to hydroponics because this pH range is hostile to most bacteria and fungi.
- Cultivars primarily cultivated for their fiber, characterized by long stems and little branching.
- Cultivars grown for seed from which hemp oil is extracted.
- Cultivars grown for medicinal or recreational purposes. A nominal if not legal distinction is often made between industrial hemp, with concentrations of psychoactive compounds far too low to be useful for that purpose, and marijuana.
Pharmacology
Although the main psychoactive chemical compound in Cannabis is ?9-tetrahydrocannabinol (THC), the plant is known to contain about sixty cannabinoids; however, most of these "minor" cannabinoids are only produced in trace amounts. Besides THC, another cannabinoid produced in high concentrations by some plants is cannabidiol (CBD), which is not psychoactive but has recently been shown to block the effect of THC in the nervous system. Differences in the chemical composition of Cannabis varieties may produce different effects in humans. Synthetic THC, called dronabinol, does not contain CBD, CBN, or other cannabinoids, which is one reason why its pharmacological effects may differ significantly from those of natural Cannabis preparations.
Chemical constituents
Cannabis has over 400 chemical constituents including about 100 compounds responsible for its characteristic aroma (see Cannabis flower essential oil). These are mainly volatile terpenes and sesquiterpenes.
Gallery of images
See also
External links
|
| |
|
|
