Fig. 2. Cannabis sativa. This superb composite plate by artist Elmer Smith, often reproduced at a very small scale and without explanation in marijuana books, is the best scientific illustration of the hemp plant ever prepared. 1. Flowering branch of male plant. 2. Flowering branch of female plant. 3. Seedling. 4. Leaflet. 5. Cluster of male flowers. 6. Female flower, enclosed by perigonal bract. 7. Mature fruit enclosed in perigonal bract. 8. Seed (achene), showing wide face. 9. Seed, showing narrow face. 10. Stalked secretory gland. 11. Top of sessile secretory gland. 12. Long section of cystolith hair (note calcium carbonate concretion at base). Reproduced with the permission of Harvard University, Cambridge, MA.
In the mid 1990s, the EU provided subsidization for hemp cultivation of ca. $1,050/ha. This support was instrumental in developing a hemp industry in western Europe. However, no comparable support is available in North America, and indeed those contemplating entering into hemp cultivation are faced with extraordinary costs and/or requirements in connection with licensing, security, THC analysis, and record keeping. Those involved in value-added processing and distribution are also faced with legal uncertainties and the regular threat of idiosyncratic, indeed irrational actions of various governments. Simply displaying a C. sativa leaf on advertising has led to the threat of criminal charges in the last decade in several G8 countries. Attempting to export or import hemp products among countries is presently a most uncertain activity.
A systematic review assessing 19 studies that evaluated premalignant or malignant lung lesions in persons 18 years or older who inhaled Cannabis concluded that observational studies failed to demonstrate statistically significant associations between Cannabis inhalation and lung cancer after adjusting for tobacco use.[8] In the review of the published meta-analyses, the National Academies of Sciences, Engineering, and Medicine (NASEM) report concluded that there was moderate evidence of no statistical association between Cannabis smoking and the incidence of lung cancer.[9]
On October 17, 2018, Canada legalized cannabis for recreational adult use[54] making it the second country in the world to do so after Uruguay and the first G7 nation.[55] The Canadian Licensed Producer system may become the Gold Standard in the world for safe and secure cannabis production,[56] including provisions for a robust craft cannabis industry where many expect opportunities for experimenting with different strains.[57] Laws around use vary from province to province including age limits, retail structure, and growing at home.[58]
Jump up ^ El-Alfy, Abir T.; Ivey, Kelly; Robinson, Keisha; Ahmed, Safwat; Radwan, Mohamed; Slade, Desmond; Khan, Ikhlas; Elsohly, Mahmoud; Ross, Samir (2010). "Antidepressant-like effect of Δ9-tetrahydrocannabinol and other cannabinoids isolated from Cannabis sativa L". Pharmacology Biochemistry and Behavior. 95 (4): 573–82. doi:10.1016/j.pbb.2010.03.004. PMC 2866040. PMID 20332000.
Hemp is a bast fiber crop, i.e. the most desirable (“long”) fibers are found in the phloem-associated tissues external to the phloem, just under the “bark.” The traditional and still major first step in fiber extraction is to ret (“rot”) away the softer parts of the plant, by exposing the cut stems to microbial decay in the field (“dew retting,” shown in Figs. 46 and 47) or submerged in water (“water retting, ” shown in Fig. 13). The result is to slough off the outer parts of the stem and to loosen the inner woody core (the “hurds”) from the phloem fibers (Fig. 14). Water retting has been largely abandoned in countries where labor is expensive or environmental regulations exist. Water retting, typically by soaking the stalks in ditches, can lead to a high level of pollution. Most hemp fiber used in textiles today is water retted in China and Hungary. Retting in tanks rather than in open bodies of water is a way of controlling the effluents while taking advantage of the high-quality fiber that is produced. Unlike flax, hemp long fiber requires water retting for preparation of high-quality spinnable fibers for production of fine textiles. Improved microorganisms or enzymes could augment or replace traditional water retting. Steam explosion is another potential technology that has been experimentally applied to hemp (Garcia-Jaldon et al. 1998). Decorticated material (i.e. separated at least into crude fiber) is the raw material, and this is subjected to steam under pressure and increased temperature which “explodes” (separates) the fibers so that one has a more refined (thinner) hemp fiber that currently is only available from water retting. Even when one has suitably separated long fiber, specialized harvesting, processing, spinning and weaving equipment are required for preparing fine hemp textiles. The refinement of equipment and new technologies are viewed as offering the possibility of making fine textile production practical in western Europe and North America, but at present China controls this market, and probably will remain dominant for the foreseeable future.
Rather than keeping people out of the industry, Money thinks regulators should focus on helping farmers sell their products: for example, by connecting them with the "biomass brokers" who deal in the fibers, stalks, and seed matter produced by industrial hemp. "What I'm finding is that a lot of farmers in Wisconsin don't know what to do with their products," she said. "We tried to get a list of licensed farmers to help connect them with brokers, but the state wouldn't release that list."

Cannabis smoke contains thousands of organic and inorganic chemical compounds. This tar is chemically similar to that found in tobacco smoke,[88] and over fifty known carcinogens have been identified in cannabis smoke,[89] including; nitrosamines, reactive aldehydes, and polycylic hydrocarbons, including benz[a]pyrene.[90] Cannabis smoke is also inhaled more deeply than is tobacco smoke.[91] As of 2015, there is no consensus regarding whether cannabis smoking is associated with an increased risk of cancer.[92] Light and moderate use of cannabis is not believed to increase risk of lung or upper airway cancer. Evidence for causing these cancers is mixed concerning heavy, long-term use. In general there are far lower risks of pulmonary complications for regular cannabis smokers when compared with those of tobacco.[93] A 2015 review found an association between cannabis use and the development of testicular germ cell tumors (TGCTs), particularly non-seminoma TGCTs.[94] A 2015 analysis of six studies found little evidence that long-term or regular cannabis smoking was associated with lung cancer risk, though it could not rule out whether an association with heavy smoking exists.[95] Another 2015 meta-analysis found no association between lifetime cannabis use and risk of head or neck cancer.[96] Combustion products are not present when using a vaporizer, consuming THC in pill form, or consuming cannabis foods.[97]
38 states and Puerto Rico considered legislation related to industrial hemp in 2017. These bills ranged from clarifying existing laws to establishing new licensing requirements and programs.  At least 15 states enacted legislation in 2017 — Arkansas, Colorado, Florida, Hawaii, North Dakota, Nevada, New York, Oregon, South Carolina, Tennessee, Virginia, Washington, West Virginia, Wisconsin and Wyoming. Florida, Wisconsin and Nevada authorized new research or pilot programs. The governors of Arizona and New Mexico vetoed legislation, which would have established new research programs. 

In recent years, a wide range of synthetic products, claiming to have similar effects to cannabis, have also been available in Australia. Synthetic cannabis is made up of chemicals that are designed to activate the same chemical systems in the brain as THC. These drugs are marketed as having similar physical and psychological effects as cannabis, but can have more unpredictable effects and are potentially more harmful than cannabis.
A systematic review assessing 19 studies that evaluated premalignant or malignant lung lesions in persons 18 years or older who inhaled Cannabis concluded that observational studies failed to demonstrate statistically significant associations between Cannabis inhalation and lung cancer after adjusting for tobacco use.[8] In the review of the published meta-analyses, the National Academies of Sciences, Engineering, and Medicine (NASEM) report concluded that there was moderate evidence of no statistical association between Cannabis smoking and the incidence of lung cancer.[9]
George Washington also imported the Indian Hemp plant from Asia, which was used for fiber and, by some growers, for intoxicating resin production. In a letter to William Pearce who managed the plants for him Washington says, "What was done with the Indian Hemp plant from last summer? It ought, all of it, to be sown again; that not only a stock of seed sufficient for my own purposes might have been raised, but to have disseminated seed to others; as it is more valuable than common hemp."[citation needed]
Hemp does best on a loose, well-aerated loam soil with high fertility and abundant organic matter. Well-drained clay soils can be used, but poorly-drained clay soils are very inappropriate because of their susceptibility to compaction, which is not tolerated. Young plants are sensitive to wet or flooded soils, so that hemp must have porous, friable, well-drained soils. Sandy soils will grow good hemp, provided that adequate irrigation and fertilization are provided, but doing so generally makes production uneconomical. Seedbed preparation requires considerable effort. Fall plowing is recommended, followed by careful preparation of a seedbed in the spring. The seedbed should be fine, level, and firm. Seed is best planted at 2–3 cm (twice as deep will be tolerated). Although the seedlings will germinate and survive at temperatures just above freezing, soil temperatures of 8°–10°C are preferable. Generally hemp should be planted after danger of hard freezes, and slightly before the planting date of maize. Good soil moisture is necessary for seed germination, and plenty of rainfall is needed for good growth, especially during the first 6 weeks. Seeding rate is specific to each variety, and this information should be sought from the supplier. Fiber strains are typically sown at a minimum rate of 250 seeds per m2 (approximately 45 kg/ha), and up to three times this density is sometimes recommended. In western Europe, seeding rates range from 60–70 kg/ha for fiber cultivars. Recommendations for seeding rates for grain production vary widely, from 10–45 kg/ha. Densities for seed production for tall, European, dual-purpose cultivars are less than for short oilseed cultivars. Low plant densities, as commonly found in growing tall European cultivars for seed, may not suppress weed growth adequately, and under these circumstances resort to herbicides may pose a problem for those wishing to grow hempseed organically. Hemp requires about the same fertility as a high-yielding crop of wheat. Industrial hemp grows well in areas that corn produces high yields. Growing hemp may require addition of up to 110 kg/ha of nitrogen, and 40–90 kg/ha of potash. Hemp particularly requires good nitrogen fertilization, more so for seed production than fiber. Adding nitrogen when it is not necessary is deleterious to fiber production, so that knowledge of the fertility of soils being used is very important. Organic matter is preferably over 3.5%, phosphorus should be medium to high (>40 ppm), potassium should be medium to high (>250 ppm), sulfur good (>5,000 ppm), and calcium not in excess (<6,000 ppm).

The question of whether heteromorphic sex chromosomes are indeed present is most conveniently answered if such chromosomes were clearly visible in a karyotype. Cannabis was one of the first plant species to be karyotyped; however, this was in a period when karyotype preparation was primitive by modern standards (see History of Cytogenetics). Heteromorphic sex chromosomes were reported to occur in staminate individuals of dioecious "Kentucky" hemp, but were not found in pistillate individuals of the same variety. Dioecious "Kentucky" hemp was assumed to use an XY mechanism. Heterosomes were not observed in analyzed individuals of monoecious "Kentucky" hemp, nor in an unidentified German cultivar. These varieties were assumed to have sex chromosome composition XX.[31] According to other researchers, no modern karyotype of Cannabis had been published as of 1996.[32] Proponents of the XY system state that Y chromosome is slightly larger than the X, but difficult to differentiate cytologically.[33]
Cohen has found that chronic conditions including autoimmune diseases and pain syndromes can be helped with a 6-mg under-the-tongue tincture (the fastest delivery system) or a 25-mg capsule taken twice a day. Dosages for topical products like lotions are especially hard to determine—there’s no clarity on how much CBD gets into the system through the skin.
Hemp is used to make a variety of commercial and industrial products including rope, textiles, clothing, shoes, food, paper, bioplastics, insulation, and biofuel.[5] The bast fibers can be used to make textiles that are 100% hemp, but they are commonly blended with other fibers, such as flax, cotton or silk, as well as virgin and recycled polyester, to make woven fabrics for apparel and furnishings. The inner two fibers of the plant are more woody and typically have industrial applications, such as mulch, animal bedding and litter. When oxidized (often erroneously referred to as "drying"), hemp oil from the seeds becomes solid and can be used in the manufacture of oil-based paints, in creams as a moisturizing agent, for cooking, and in plastics. Hemp seeds have been used in bird feed mix as well.[13] A survey in 2003 showed that more than 95% of hemp seed sold in the European Union was used in animal and bird feed.[14]