Cannabis sativa

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iCannabis sativa
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Order: Rosales Family: Cannabaceae Genus: Cannabis Species: C. sativa
Binomial name
Cannabis sativa Linnaeus
Subspecies
C. sativa L subsp. sativa C. sativa L subsp. indica

Cannabis sativa, also known as hemp, is a species of Cannabis. It is a dioecious, annual herb. It has been used by humans throughout recorded history for its fiber, for its psychological and physiological potential as a source of drug material, and for the nourishment and oil of its seeds. Different parts of the herb have different uses and different varieties are cultivated in different ways, and harvested at different times, depending on the purpose for which the herb is grown.

Subspecies

Main article: Taxonomy of Cannabis

Cannabis

Cannabis sativa

C. sativa subsp. sativa

C. sativa subsp. sativa var. sativa

C. sativa subsp. sativa var spontanea

C. sativa subsp. indica

C. sativa subsp. sativa

C. sativa subsp. sativa var. sativa

This variety includes types cultivated for hemp and drug production. Plants are typically tall and laxly branched, and have relatively narrow leaflets. Drug cultivars usually produce relatively high ratios of THC to CBD.

C. sativa subsp. sativa var. spontanea

Correct name: C. sativa L subsp. sativa var. spontanea Vav.

Synonym: C. ruderalis Janisch.

This variety includes wild, feral, or escaped Cannabis. In the absence of selective breeding, these plants have lost many of the traits they were originally selected for, and have acclimatized to their locales. Plants of this type are short, branchless, early-flowering and can withstand much harsher climates than other types. The plants have low overall levels of THC, and a low ratio of THC to CBD, and thus are of little use as a source of drugs. However, C. indica drug strains are frequently cross-bred with C. ruderalis to produce plants combining a higher THC content with the hardiness and reduced height of ruderalis.

The term "Ruderalis" was originally used in the former Soviet Union to describe the varieties of hemp that had escaped cultivation and adapted to the surrounding region. Plants of this type are widespread throughout central and eastern Europe, including Lithuania, Belarus, Latvia, and Estonia. Similar populations can be found in most of the areas where hemp cultivation was once prevalent. The most notable region in North America is the midwest, though populations occur sporadically throughout the United States and Canada.

Cannabis users often call this wild cannabis "ditch weed." Outside of it's native range, it is regarded as an invasive plant. Despite years of government-sponsored eradication programs, these wild plants still remain in bountiful abundance.

It has several times been proposed that this type of Cannabis be recognized as a distinct species, called C. ruderalis.

C. sativa subsp. indica

Correct name: C. sativa L subsp. indica (Lam.) E. Small & Cronquist

Synonym: C. indica Lam.

Broad leaflets characteristic of C. sativa subsp. indica

It has often been proposed that this type be recognized as a distinct species, C. indica. Most recently, on the basis of genetic analysis, it has been proposed that both the narrow-leaflet and wide-leaflet drug "biotypes", as well as southern and eastern Asian hemp (fiber/seed) landraces and wild Himalayan populations, be recognized as a distinct species, C. indica.^[6]

Common uses

Main articles: Hemp and Cannabis (drug)

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 much 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

Main article: Cannabis

Cannabis sativa, scientific drawing from c1900

Size of a large C. Sativa seed.

Cannabis reproduces sexually. The flowers of the female plant, in cannabis usually called buds, are arranged in racemes and can produce hundreds of seeds. Males reach sexual maturity several weeks prior to females. Although genetics disposes a plant to become male, environmental factors, including the diurnal light cycle, can alter the sex. Natural hermaphrodites, with both male and female parts, are either sterile or fertile but artificially induced hermaphrodites 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 cycle can thrive under twenty-four hour daylight conditions, although some growers advocate a small rest period to avoid overstressing the plant. Flowering usually occurs when darkness exceeds eleven hours per day. The flowering cycle can last anywhere between six to twelve 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 fibre, 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 hemp, with concentrations of psychoactive compounds far too low to be useful for that purpose, and marijuana.

Pharmacology

Main article: Cannabis (drug)

Though the main psychoactive chemical compound in cannabis is Delta-9-tetrahydrocannabinol (THC), the plant is known to contain about sixty cannabinoids. One other cannabinoid of particularly high concentration in some plants is cannabidiol (CBD), which is not psychoactive but modifies the effect of THC. 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 cannabis preparations.

Most commonly available cannabis contains below 8% THC.^[7] Selective breeding and modern cultivation techniques like hydroponics have produced varieties with more than 15% THC ^{[citation needed]}. With varieties containing below 2% THC, such as those specifically cultivated for use as hemp, smoking may produce lightheadedness or mild headache but not inebriation. The THC content is also affected by the sex of the plant, with female plants generating substantially more resin than their male counterparts. Seedless varieties derived from unpollinated female plants have high THC content and are traditionally known as sinsemilla (Spanish: "without seed").

References

External links

• Marijuana and Medicine: Assessing the Science Base
• Four full pages of photos of cannabis cultivation in Morocco (Rif) on www.geopium.org

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