大麻的多樣性，人類已馴化很久作物，約從 6000 年前開始種植，有非常多的栽培種，特別主要三種 : 取用纖維造紙，紡織品和繩索、“種子”（瘦果）中的油和營養成分與精神興奮劑。
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I come in many names - cannabis, marijuana, hemp, crack, pot, dope, reefer, ganja
Cannabis is a genus of flowering plants in the family Cannabaceae. The number of species within the genus is disputed. Three species may be recognized: Cannabis sativa, Cannabis indica, and Cannabis ruderalis; C. ruderalis may be included within C. sativa; or all three may be treated as subspecies of a single species, C. sativa. The genus Cannabis was formerly placed in the Nettle (Urticaceae) or Mulberry (Moraceae) family, and later, along with the Humulus genus (hops), in a separate family, the Hemp family (Cannabaceae sensu stricto). Recent phylogenetic studies based on cpDNA restriction site analysis and gene sequencing strongly suggest that the Cannabaceae sensu stricto arose from within the former Celtidaceae family, and that the two families should be merged to form a single monophyletic family, the Cannabaceae sensu lato.
Cannabis is an annual, dioecious, flowering herb. The leaves are palmately compound or digitate, with serrate leaflets. The first pair of leaves usually have a single leaflet, the number gradually increasing up to a maximum of about thirteen leaflets per leaf (usually seven or nine), depending on variety and growing conditions. At the top of a flowering plant, this number again diminishes to a single leaflet per leaf. The lower leaf pairs usually occur in an opposite leaf arrangement and the upper leaf pairs in an alternate arrangement on the main stem of a mature plant.
The leaves have a peculiar and diagnostic venation pattern that enables persons poorly familiar with the plant to distinguish a cannabis leaf from unrelated species that have confusingly similar leaves (see illustration). As is common in serrated leaves, each serration has a central vein extending to its tip. However, the serration vein originates from lower down the central vein of the leaflet, typically opposite to the position of, not the first notch down, but the next notch. This means that on its way from the midrib of the leaflet to the point of the serration, the vein serving the tip of the serration passes close by the intervening notch. Sometimes the vein will actually pass tangent to the notch, but often it will pass by at a small distance, and when that happens a spur vein (occasionally a pair of such spur veins) branches off and joins the leaf margin at the deepest point of the notch. This venation pattern varies slightly among varieties, but in general it enables one to tell Cannabis leaves from superficially similar leaves without difficulty and without special equipment. Tiny samples of Cannabis plants also can be identified with precision by microscopic examination of leaf cells and similar features, but that requires special expertise and equipment.
Cannabis is a genus characterized by dioecy, with male individuals showing short life cycle, and higher and slimmer shoots compared to female ones, but cultivars that produce also hermaphrodite or monoecious flowers (bearing separate male and female flowers on the same individual) are well known. Cannabis is wind pollinated; male plants produce vast amounts of pollen that can spread over large geographical areas, allowing the pollination of female flowers of plants growing very far from pollen-bearing flowers.
Cannabis species in the wild had a weedy attitude, growing in soils with high concentrations of nitrogen released by animal dejections and human activities. The long coexistence between mankind and hemp led to an early domestication of the plant, which soon showed an amazing spectrum of possible utilizations.
Cannabis has been specially domesticated to enhance the production of three main plant parts: the bast (phloem) fiber in the stem, the oil and nutritious content in the “seeds” (achenes), and the psychotropic Tetrahydrocannabinol (and other cannabinoids) with the highest concentration in the female flowers (Small and Marcus). Historically, hemp, the variety grown for its low psychoactive component, was grown for industrial applications, such as paper, textiles, and cordage but today has gained immense popularity for a variety of “products including health foods, organic body care, clothing, construction materials, biofuels, plastic composites and more”. C. sativa has been touted as useful for 25,000 products “ranging from dynamite to Cellophane”. Nutritionally, the seeds of C. sativa are a vegetarian source of omega-3 fatty acids, are a complete source of protein (they contain all of the essential amino acids), and are also a potent source of multiple essential minerals, including magnesium, phosphorus, iron, and zinc (Corleone).
The extent of Cannabis domestication has been so persistent to cause the disappearing of the wild species: nowadays, the specie(s) belonging to the genus Cannabis are represented by myriads of cultivated varieties, which occasionally escape cultivation and grow also in the wild, giving life to forms that lose some features typical of cultivated ones. For this reason, the nomenclature of Cannabis has unstable foundations and has been the object of numerous taxonomic treatments. Hundreds of Cannabis cultivated varieties have been developed and named with vernacular names by medical patients and recreational users. Few of these can be treated as real Cannabis cultivars, having been regularly named and registered according to the ICNCP, but many others, particularly marijuana strains, lack an adequate description and a standard. For this reason, their names cannot be accepted as cultivar epithets. Any strain that has not been formally described as a cultivar, for example, the so called Sour diesel, or Granddaddy Purple, should be named as follows: Cannabis strain Sour diesel, or strain Granddaddy Purple, with their popularized name without single quotation marks, having in mind that their names have no taxonomical validity.
The area of origin and domestication of Cannabis sativa is widely believed to be in Central Asia. Specifically, it is believed to have originated in the upland valleys of the Tian Shan (a system of mountain ranges located in Himalaya) or Altai Mountains, where the first uses and cultivation of C. sativa are also thought to have originated. C. sativa speciation occurred during the early Pleistocene, and domestication occurred more than a few million years later in the same region.
In 2003, a formal excavation of a shaman tomb in the Yanghai Tombs near Turpan, Xinjiang-Uighur Autonomous Region, China, revealed the oldest evidence of C. sativa cultivated specifically for its psychoactive components. 789 grams (1.7 pounds) of potent C. sativa was found near the head and foot of the shaman’s bier within a wooden bowl and large leather basket. The C. sativa had been pounded and the wooden bowl worn smooth, evidently from use as a mortar. It was dated to 2700 years BCE, based on the age of artifacts around it as well as tree ring data (dendrochronology) in China. The C. sativa had relatively large achenes, their color was light with some striations, and they had rough, non-concave fruit attachment; all these traits are clear markers of domestication. Other archaeological evidence comes from a postglacial fishing site from 12,000 BCE in southern China; cord-impressed pottery was found with hemp likely being the cordage used. Carbonized hemp seed was found on a house floor within pottery in an ancient western Yangshao site in northwestern China dated to 5500 to 4500 BCE.
There are voluminous ancient texts and historical references to C. sativa throughout Central Asia; “from a historical vantage, Cannabis has been found in China since Neolithic times, about 6,000 years ago, with a continuous record of cultivation down to the present”. According to classic Chinese literature, Shen Nung (ca. 2800 BCE), a celebrated herbalist and patron divinity (whose name literally means “Divine Farmer”), was the first to instruct his people to cultivate hemp, and he also prescribed it for medicinal purposes One of Confucius’s “Five Classics,” from the second century, titled “Li Chi” (“Record of Rites”), refers to C. sativa many times, from proper etiquette for ritual C. sativa use to wearing appropriate hemp mourning clothes. As Hui-Lin Li once marveled, “detailed instructions on the cultivation of hemp as both a fiber and a grain crop were given in the most ancient works on agriculture in existence” (Li “The Origin” 295). Relevantly, the oldest paper known to man was made out of hemp, discovered in 1957 within a grave in Shensi province (near Xian, China); it was dated to 104-87 BCE (Li “The Origin” 294).
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