Cannabis is indigenous to Central Asia and Indian subcontinent, and its use for fabric and rope dates back to the Neolithic age in China and Japan. It is unclear when cannabis first became known for its psychoactive properties; some scholars suggest that the ancient Indian drug soma, mentioned in the Vedas, was cannabis, although this theory is disputed.
Cannabis is mostly used for recreation or as a medicinal drug, although it may also be used for spiritual purposes. In 2013, between 128 and 232 million people used cannabis (2.7% to 4.9% of the global population between the ages of 15 and 65). It is the most commonly used illegal drug both in the world and the United States. The countries with the highest use among adults as of 2018 are Zambia, the United States, Canada, and Nigeria. In 2016, 51% of people in the United States had ever used cannabis. About 12% had used it in the past year, and 7.3% had used it in the past month.
Highly selected forms of the fiber cultigen possess features maximizing fiber production. Since the nodes tend to disrupt the length of the fiber bundles, thereby limiting quality, tall, relatively unbranched plants with long internodes have been selected. Another strategy has been to select stems that are hollow at the internodes, with limited wood, since this maximizes production of fiber in relation to supporting woody tissues. Similarly, limited seed productivity concentrates the plant’s energy into production of fiber, and fiber cultivars often have low genetic propensity for seed output. Selecting monoecious strains overcomes the problem of differential maturation times and quality of male (staminate) and female (pistillate) plants (males mature 1–3 weeks earlier). Male plants in general are taller, albeit slimmer, less robust, and less productive. Except for the troublesome characteristic of dying after anthesis, male traits are favored for fiber production, in contrast to the situation for drug strains noted below. In former, labor-intensive times, the male plants were harvested earlier than the females, to produce superior fiber. The limited branching of fiber cultivars is often compensated for by possession of large leaves with wide leaflets, which obviously increase the photosynthetic ability of the plants. Since fiber plants have not generally been selected for narcotic purposes, the level of intoxicating constituents is usually limited.
An absence of such fiber-strain traits as tallness, limited branching, long internodes, and very hollow stems, is characteristic of narcotic strains. Drug forms have historically been grown in areas south of the north-temperate zone, often close to the equator, and are photoperiodically adapted to a long season. When grown in north-temperate climates maturation is much-delayed until late fall, or the plants succumb to cold weather before they are able to produce seeds. Unlike fiber strains that have been selected to grow well at extremely high densities, drug strains tend to be less persistent when grown in high concentration (de Meijer 1994). Drug strains can be very similar in appearance to fiber strains. However, a characteristic type of narcotic plant was selected in southern Asia, particularly in India and neighboring countries. This is dioecious, short (about a meter in height), highly branched, with large leaves (i.e. wide leaflets), and it is slow to mature. The appearance is rather like a short, conical Christmas tree.
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One of the most curious uses of hemp is as a fence to prevent pollen transfer in commercial production of seeds. Isolation distances for ensuring that seeds produced are pure are considerable for many plants, and often impractical. At one point in the 1980s, the only permitted use of hemp in Germany was as a fence or hedge to prevent plots of beets being used for seed production from being contaminated by pollen from ruderal beets. The high and rather inpenetrable hedge that hemp can produce was considered unsurpassed by any other species for the purpose. As well, the sticky leaves of hemp were thought to trap pollen. However, Saeglitz et al. (2000) demonstrated that the spread of beet pollen is not effectively prevented by hemp hedges. Fiber (i.e. tall) cultivars of hemp were also once used in Europe as wind-breaks, protecting vulnerable crops against wind damage. Although hemp plants can lodge, on the whole very tall hemp is remarkably resistant against wind.
Of course, the easiest solution, advocates say, is for the federal government to legalize cannabis completely. If cannabis were legalized—the whole plant and all its extracts, no confusing singling-out of specific compounds or anatomical features—then U.S. drug companies would be able to carefully cultivate and research its medicinal properties, and submit their findings to regulatory bodies like the FDA for trials and approval.
The United Kingdom and Germany resumed commercial production in the 1990s. British production is mostly used as bedding for horses; other uses are under development. Companies in Canada, the UK, the United States, and Germany, among many others, process hemp seed into a growing range of food products and cosmetics; many traditional growing countries still continue to produce textile-grade fibre.
Until recent times, the cultivation of hemp primarily as an oilseed was largely unknown, except in Russia. Today, it is difficult to reconstruct the type of plant that was grown there as an oilseed, because such cultivation has essentially been abandoned. Oilseed hemp cultivars in the modern sense were not available until very recently, but some land races certainly were grown specifically for seeds in Russia. Dewey (1914) gave the following information: “The short oil-seed hemp with slender stems, about 30 inches high, bearing compact clusters of seeds and maturing in 60 to 90 days, is of little value for fiber production, but the experimental plants, grown from seed imported from Russia, indicate that it may be valuable as an oil-seed crop to be harvested and threshed in the same manner as oil-seed flax.” Most hemp oilseed in Europe is currently obtained from so-called “dual usage” plants (employed for harvest of both stem fiber and seeds, from the same plants). Of the European dual-usage cultivars, ‘Uniko B’ and ‘Fasamo’ are particularly suited to being grown as oilseeds. Very recently, cultivars have been bred specifically for oilseed production. These include ‘Finola,’ formerly known as ‘Fin-314’ (Fig. 6) and ‘Anka’ (Fig. 7), which are relatively short, little-branched, mature early in north-temperate regions, and are ideal for high-density planting and harvest with conventional equipment. Dewey (1914) noted that a Turkish narcotic type of land race called “Smyrna” was commonly used in the early 20th century in the US to produce birdseed, because (like most narcotic types of Cannabis) it is densely branched, producing many flowers, hence seeds. While oilseed land races in northern Russia would have been short, early-maturing plants in view of the short growing season, in more southern areas oilseed landraces likely had moderate height, and were spaced more widely to allow abundant branching and seed production to develop. Until Canada replaced China in 1998 as a source of imported seeds for the US, most seeds used for various purposes in the US were sterilized and imported from China. Indeed, China remains the largest producer of hempseed. We have grown Chinese hemp land races, and these were short, branched, adapted to a very long growing season (i.e. they come into flower very slowly in response to photoperiodic induction of short days in the fall), and altogether they were rather reminiscent of Dewey’s description of Smyrna. Although similar in appearance to narcotic strains of C. sativa, the Chinese land races we grew were in fact low in intoxicating constituents, and it may well be that what Dewey thought was a narcotic strain was not. Although some forms of C. sativa have quite large seeds, until recently oilseed forms appear to have been mainly selected for a heavy yield of seeds, usually recognizable by abundant branching. Such forms are typically grown at lower densities than hemp grown only for fiber, as this promotes branching, although it should be understood that the genetic propensity for branching has been selected. Percentage or quality of oil in the seeds does not appear to have been important in the past, although selection for these traits is now being conducted. Most significantly, modern selection is occurring with regard to mechanized harvesting, particularly the ability to grow in high density as single-headed stalks with very short branches bearing considerable seed.
Tocopherols. Tocopherols are major antioxidants in human serum. Alpha- beta-, gamma- and delta-tocopherol represent the vitamin E group. These fat-soluble vitamins are essential for human nutrition, especially the alpha-form, which is commonly called vitamin E. About 80% of the tocopherols of hempseed oil is the alpha form. The vitamin E content of hempseed is comparatively high. Antioxidants in hempseed oil are believed to stabilize the highly polyunsaturated oil, tending to keep it from going rancid. Sterols in the seeds probably serve the same function, and like the tocopherols are also desirable from a human health viewpoint.
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