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.
THC and its major (inactive) metabolite, THC-COOH, can be measured in blood, urine, hair, oral fluid or sweat using chromatographic techniques as part of a drug use testing program or a forensic investigation of a traffic or other criminal offense. The concentrations obtained from such analyses can often be helpful in distinguishing active use from passive exposure, elapsed time since use, and extent or duration of use. These tests cannot, however, distinguish authorized cannabis smoking for medical purposes from unauthorized recreational smoking. Commercial cannabinoid immunoassays, often employed as the initial screening method when testing physiological specimens for marijuana presence, have different degrees of cross-reactivity with THC and its metabolites. Urine contains predominantly THC-COOH, while hair, oral fluid and sweat contain primarily THC. Blood may contain both substances, with the relative amounts dependent on the recency and extent of usage.
Cannabinoids, terpenoids, and other compounds are secreted by glandular trichomes that occur most abundantly on the floral calyxes and bracts of female plants. As a drug it usually comes in the form of dried flower buds (marijuana), resin (hashish), or various extracts collectively known as hashish oil. In the early 20th century, it became illegal in most of the world to cultivate or possess Cannabis for sale or personal use.
Hash oil is a resinous matrix of cannabinoids obtained from the Cannabis plant by solvent extraction, formed into a hardened or viscous mass. Hash oil can be the most potent of the main cannabis products because of its high level of psychoactive compound per its volume, which can vary depending on the plant's mix of essential oils and psychoactive compounds. Butane and supercritical carbon dioxide hash oil have become popular in recent years.