Professors William Emboden, Loran Anderson, and Harvard botanist Richard E. Schultes and coworkers also conducted taxonomic studies of Cannabis in the 1970s, and concluded that stable morphological differences exist that support recognition of at least three species, C. sativa, C. indica, and C. ruderalis. For Schultes, this was a reversal of his previous interpretation that Cannabis is monotypic, with only a single species. According to Schultes' and Anderson's descriptions, C. sativa is tall and laxly branched with relatively narrow leaflets, C. indica is shorter, conical in shape, and has relatively wide leaflets, and C. ruderalis is short, branchless, and grows wild in Central Asia. This taxonomic interpretation was embraced by Cannabis aficionados who commonly distinguish narrow-leafed "sativa" strains from wide-leafed "indica" strains.
bNumber of patients treated plus number of patient controls may not equal number of patients enrolled; number of patients enrolled equals number of patients initially recruited/considered by the researchers who conducted a study; number of patients treated equals number of enrolled patients who were given the treatment being studied AND for whom results were reported.
Hemp crops are tall, have thick foliage, and can be planted densely, and thus can be grown as a smother crop to kill tough weeds. Using hemp this way can help farmers avoid the use of herbicides, gain organic certification, and gain the benefits of crop rotation. However, due to the plant's rapid and dense growth characteristics, some jurisdictions consider hemp a prohibited and noxious weed, much like Scotch Broom.
^ Jump up to: a b c Whiting, PF; Wolff, RF; Deshpande, S; Di Nisio, M; Duffy, S; Hernandez, AV; Keurentjes, JC; Lang, S; Misso, K; Ryder, S; Schmidlkofer, S; Westwood, M; Kleijnen, J (23 June 2015). "Cannabinoids for Medical Use: A Systematic Review and Meta-analysis" (PDF). JAMA. 313 (24): 2456–2473. doi:10.1001/jama.2015.6358. hdl:10757/558499. PMID 26103030.
Hemp paper is useful for specialty applications such as currency and cigarette papers where strength is needed. The bast fiber is of greatest interest to the pulp and paper industry because of its superior strength properties compared to wood. However, the short, bulky fibers found in the inner part of the plant (hurds) can also be used to make cheaper grades of paper, apparently without greatly affecting quality of the printing surface. Hemp is not competitive for newsprint, books, writing papers, and general paper (grocery bags, coffee cups, napkins), although there is a specialty or novelty market for those specifically wishing to support the hemp industry by purchasing hemp writing or printing paper despite the premium price (Fig. 17).
Jews living in Palestine in the 2nd century were familiar with the cultivation of hemp, as witnessed by a reference to it in the Mishna (Kil'ayim 2:5) as a variety of plant, along with Arum, that sometimes takes as many as three years to grow from a seedling. In late medieval Germany and Italy, hemp was employed in cooked dishes, as filling in pies and tortes, or boiled in a soup. Hemp in later Europe was mainly cultivated for its fibers, and was used for ropes on many ships, including those of Christopher Columbus. The use of hemp as a cloth was centered largely in the countryside, with higher quality textiles being available in the towns.
In Buddhism, cannabis is generally regarded as an intoxicant and may be a hindrance to development of meditation and clear awareness. In ancient Germanic culture, Cannabis was associated with the Norse love goddess, Freya. An anointing oil mentioned in Exodus is, by some translators, said to contain Cannabis. Sufis have used Cannabis in a spiritual context since the 13th century CE.
Unlike other Cannabis sativa varieties and hybrids, which are mostly grown for their chemically potent flowers (or 'buds'), hemp is also legally distinguished from marijuana in the US as containing less than 0.3% of the cannabinoid chemical THC — considered to be the most intoxicating, psychoactive component in cannabis plants, as well as a treatment option for certain serious illnesses.
The Drug Enforcement Agency and the Office of National Drug Control Policy of the US raised concerns over tests conducted from 1995 to 1997 that showed that consumption of hempseed products available during that period led to interference with drug-testing programs for marijuana use. Federal US programs utilize a THC metabolite level of 50 parts per billion in urine. Leson (2000) found that this level was not exceeded by consuming hemp products, provided that THC levels are maintained below 5 ppm in hemp oil, and below 2 ppm in hulled seeds. Nevertheless the presence of even minute trace amounts of THC in foods remains a tool that can be used by those wishing to prevent the hemp oilseed industry from developing.
Medical marijuana can soothe nausea and increase appetite, quiet pain, soothe anxiety and even reduce epileptic seizures. Other research on the healing effects of cannabis is being examined. For example, research suggests that THC may be able to improve memory according to a 2016 study on mice. More than half of the United States has legalized marijuana for medical use.
Hemp has at times in the past been grown simply for its ornamental value. The short, strongly-branched cultivar ‘Panorama’ (Fig. 43) bred by Iván Bósca, the dean of the world’s living hemp breeders, was commercialized in Hungary in the 1980s, and has been said to be the only ornamental hemp cultivar available. It has had limited success, of course, because there are very few circumstances that permit private gardeners can grow Cannabis as an ornamental today. By contrast, beautiful ornamental cultivars of opium poppy are widely cultivated in home gardens across North America, despite their absolute illegality and the potentially draconian penalties that could be imposed. Doubtless in the unlikely event that it became possible, many would grow hemp as an ornamental.
In the UK, the Department for Environment, Food and Rural Affairs treats hemp as a purely non-food crop, but with proper licensing and proof of less than 0.2% THC concentration, hemp seeds can be imported for sowing or for sale as a food or food ingredient. In the U.S., imported hemp can be used legally in food products and, as of 2000, was typically sold in health food stores or through mail order.