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104-442: Cannabis ( / ˈ k æ n ə b ɪ s / ) 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 , C. indica , and C. ruderalis . Alternatively, C. ruderalis may be included within C. sativa , or all three may be treated as subspecies of C. sativa , or C. sativa may be accepted as

208-414: A chromosome complement of 2n=20, although polyploid individuals have been artificially produced. The first genome sequence of Cannabis , which is estimated to be 820 Mb in size, was published in 2011 by a team of Canadian scientists. The genus Cannabis was formerly placed in the nettle family ( Urticaceae ) or mulberry family ( Moraceae ), and later, along with the genus Humulus ( hops ), in

312-493: A genetic analysis of the same set of accessions led to a three-species classification, recognizing C. sativa , C. indica , and (tentatively) C. ruderalis . Another paper in the series on chemotaxonomic variation in the terpenoid content of the essential oil of Cannabis revealed that several wide-leaflet drug strains in the collection had relatively high levels of certain sesquiterpene alcohols, including guaiol and isomers of eudesmol, that set them apart from

416-557: A species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in the nomenclature codes , which allow each species a single unique name that, for animals (including protists ), plants (also including algae and fungi ) and prokaryotes ( bacteria and archaea ), is Latin and binomial in form; this contrasts with common or vernacular names , which are non-standardized, can be non-unique, and typically also vary by country and language of usage. Except for viruses ,

520-408: A broad spectrum of behaviors and physiology, including hibernation, seasonal migrations, and coat color changes. A prime example of the adaptation to photoperiods is the seasonal coat color (SCC) species. These animals undergo molting, transforming from dark summer fur to white coat in winter, that provides crucial camouflage in snowy environments. The view has been expressed that humans' seasonality

624-531: A four group division: In 1785, evolutionary biologist Jean-Baptiste de Lamarck published a description of a second species of Cannabis , which he named Cannabis indica Lam. Lamarck based his description of the newly named species on morphological aspects (trichomes, leaf shape) and geographic localization of plant specimens collected in India. He described C. indica as having poorer fiber quality than C. sativa , but greater utility as an inebriant . Also, C. indica

728-493: A further subdivision, obligate photoperiodic plants absolutely require a long or short enough night before flowering, whereas facultative photoperiodic plants are more likely to flower under one condition. Phytochrome comes in two forms: P r and P fr . Red light (which is present during the day) converts phytochrome to its active form (P fr ) which then stimulates various processes such as germination, flowering or branching. In comparison, plants receive more far-red in

832-1081: A high degree of potential variation for selection, even in heavily selected hemp cultivars. They also commented that these analyses confirm the continuity of the Cannabis gene pool throughout the studied accessions, and provide further confirmation that the genus consists of a single species, although theirs was not a systematic study per se . An investigation of genetic, morphological, and chemotaxonomic variation among 157 Cannabis accessions of known geographic origin, including fiber, drug, and feral populations showed cannabinoid variation in Cannabis germplasm . The patterns of cannabinoid variation support recognition of C. sativa and C. indica as separate species, but not C. ruderalis . C. sativa contains fiber and seed landraces, and feral populations, derived from Europe, Central Asia, and Turkey . Narrow-leaflet and wide-leaflet drug accessions, southern and eastern Asian hemp accessions, and feral Himalayan populations were assigned to C. indica . In 2005,

936-416: A large number of chemicals as part of their defense against herbivory . One group of these is called cannabinoids , which induce mental and physical effects when consumed . Cannabinoids, terpenes , terpenoids , and other compounds are secreted by glandular trichomes that occur most abundantly on the floral calyxes and bracts of female plants. Cannabis , like many organisms, is diploid , having

1040-643: A later homonym of a validly published name is a nomen illegitimum or nom. illeg. ; for a full list refer to the International Code of Nomenclature for algae, fungi, and plants and the work cited above by Hawksworth, 2010. In place of the "valid taxon" in zoology, the nearest equivalent in botany is " correct name " or "current name" which can, again, differ or change with alternative taxonomic treatments or new information that results in previously accepted genera being combined or split. Prokaryote and virus codes of nomenclature also exist which serve as

1144-449: A long history of being used for medicinal purposes , and as a recreational drug known as marijuana or weed . Various cannabis strains have been bred, often selectively to produce high or low levels of tetrahydrocannabinol (THC), a cannabinoid and the plant's principal psychoactive constituent . Compounds such as hashish and hash oil are extracted from the plant. Cannabis is a Scythian word. The ancient Greeks learned of

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1248-621: A long time and redescribed as new by a range of subsequent workers, or if a range of genera previously considered separate taxa have subsequently been consolidated into one. For example, the World Register of Marine Species presently lists 8 genus-level synonyms for the sperm whale genus Physeter Linnaeus, 1758, and 13 for the bivalve genus Pecten O.F. Müller, 1776. Within the same kingdom, one generic name can apply to one genus only. However, many names have been assigned (usually unintentionally) to two or more different genera. For example,

1352-450: A long-day plant can flower if exposed to more red-light in the middle of the night. Cryptochromes are another type of photoreceptor that is important in photoperiodism. Cryptochromes absorb blue light and UV-A. Cryptochromes entrain the circadian clock to light. It has been found that both cryptochrome and phytochrome abundance relies on light and the amount of cryptochrome can change depending on day-length. This shows how important both of

1456-413: A mature plant. The leaves have a peculiar and diagnostic venation pattern (which varies slightly among varieties) that allows for easy identification of Cannabis leaves from unrelated species with similar leaves. As is common in serrated leaves, each serration has a central vein extending to its tip, but in Cannabis this originates from lower down the central vein of the leaflet, typically opposite to

1560-516: A mind-altering drug has been documented by archaeological finds in prehistoric societies in Eurasia and Africa. The oldest written record of cannabis usage is the Greek historian Herodotus 's reference to the central Eurasian Scythians taking cannabis steam baths. His ( c.  440 BCE ) Histories records, "The Scythians, as I said, take some of this hemp-seed [presumably, flowers], and, creeping under

1664-409: A reference for designating currently accepted genus names as opposed to others which may be either reduced to synonymy, or, in the case of prokaryotes, relegated to a status of "names without standing in prokaryotic nomenclature". An available (zoological) or validly published (botanical) name that has been historically applied to a genus but is not regarded as the accepted (current/valid) name for

1768-633: 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 family Celtidaceae, and that the two families should be merged to form a single monophyletic family, the Cannabaceae sensu lato . Various types of Cannabis have been described, and variously classified as species , subspecies , or varieties : Cannabis plants produce

1872-449: A series of long days followed by short days whereas SLDPs flower after a series of short days followed by long days. Each plant has a different length critical photoperiod, or critical night length. Many flowering plants (angiosperms) use a circadian rhythm together with photoreceptor protein , such as phytochrome or cryptochrome , to sense seasonal changes in night length, or photoperiod, which they take as signals to flower. In

1976-411: 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

2080-506: A single undivided species. The genus is widely accepted as being indigenous to and originating from Asia . The plant is also known as hemp , although this term is often used to refer only to varieties of Cannabis cultivated for non-drug use. Cannabis has long been used for hemp fibre , hemp seeds and their oils , hemp leaves for use as vegetables and as juice . Industrial hemp products are made from cannabis plants selected to produce an abundance of fibre. Cannabis also has

2184-570: A species. Photoperiodism affects flowering by inducing the shoot to produce floral buds instead of leaves and lateral buds. Some short-day facultative plants are: Day-neutral plants, such as cucumbers , roses , tomatoes , and Ruderalis ( autoflowering cannabis ) do not initiate flowering based on photoperiodism. Instead, they may initiate flowering after attaining a certain overall developmental stage or age, or in response to alternative environmental stimuli, such as vernalisation (a period of low temperature). Daylength, and thus knowledge of

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2288-735: A subject of debate for well over two centuries. This is a contentious issue because there is no universally accepted definition of a species . One widely applied criterion for species recognition is that species are "groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups." Populations that are physiologically capable of interbreeding, but morphologically or genetically divergent and isolated by geography or ecology, are sometimes considered to be separate species. Physiological barriers to reproduction are not known to occur within Cannabis , and plants from widely divergent sources are interfertile. However, physical barriers to gene exchange (such as

2392-427: A taxon; however, the names published in suppressed works are made unavailable via the relevant Opinion dealing with the work in question. In botany, similar concepts exist but with different labels. The botanical equivalent of zoology's "available name" is a validly published name . An invalidly published name is a nomen invalidum or nom. inval. ; a rejected name is a nomen rejiciendum or nom. rej. ;

2496-519: A taxonomic revision that recognizes a single species of Cannabis with two subspecies (hemp or drug; based on THC and CBD levels) and two varieties in each (domesticated or wild). The framework is thus: This classification was based on several factors including interfertility, chromosome uniformity, chemotype, and numerical analysis of phenotypic characters. Professors William Emboden, Loran Anderson, and Harvard botanist Richard E. Schultes and coworkers also conducted taxonomic studies of Cannabis in

2600-587: A three species system, independently reinforced by Schultes et al (1975) and Emboden (1974): C. sativa , C. indica and C. ruderalis. In 1940, Russian botanists Serebriakova and Sizov proposed a complex poly-species classification in which they also recognized C. sativa and C. indica as separate species. Within C. sativa they recognized two subspecies: C. sativa L. subsp. culta Serebr. (consisting of cultivated plants), and C. sativa L. subsp. spontanea (Vav.) Serebr. (consisting of wild or feral plants). Serebriakova and Sizov split

2704-455: A total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and

2808-447: A unique family of terpeno-phenolic compounds called cannabinoids, some of which produce the "high" which may be experienced from consuming marijuana. There are 483 identifiable chemical constituents known to exist in the cannabis plant, and at least 85 different cannabinoids have been isolated from the plant. The two cannabinoids usually produced in greatest abundance are cannabidiol (CBD) and/or Δ- tetrahydrocannabinol (THC), but only THC

2912-992: Is commonly described as "auto-flowering" and may be day-neutral . Cannabis is predominantly dioecious , having imperfect flowers , with staminate "male" and pistillate "female" flowers occurring on separate plants. "At a very early period the Chinese recognized the Cannabis plant as dioecious", and the (c. 3rd century BCE) Erya dictionary defined xi 枲 "male Cannabis " and fu 莩 (or ju 苴 ) "female Cannabis ". Male flowers are normally borne on loose panicles , and female flowers are borne on racemes . Many monoecious varieties have also been described, in which individual plants bear both male and female flowers. (Although monoecious plants are often referred to as "hermaphrodites", true hermaphrodites – which are less common in Cannabis – bear staminate and pistillate structures together on individual flowers, whereas monoecious plants bear male and female flowers at different locations on

3016-484: Is determined or strongly influenced by environmental factors. Ainsworth reviews that treatment with auxin and ethylene have feminizing effects, and that treatment with cytokinins and gibberellins have masculinizing effects. It has been reported that sex can be reversed in Cannabis using chemical treatment. A polymerase chain reaction -based method for the detection of female-associated DNA polymorphisms by genotyping has been developed. Cannabis plants produce

3120-596: Is discouraged by both the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants , there are some five thousand such names in use in more than one kingdom. For instance, A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). The type genus forms

3224-553: Is either a variety of C. sativa or a separate species, and proposed C. sativa L. var. ruderalis Janisch, and Cannabis ruderalis Janisch, as alternative names. In 1929, renowned plant explorer Nikolai Vavilov assigned wild or feral populations of Cannabis in Afghanistan to C. indica Lam. var. kafiristanica Vav., and ruderal populations in Europe to C. sativa L. var. spontanea Vav. Vavilov, in 1931, proposed

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3328-440: Is largely believed to be evolutionary baggage . . Human birth rate varies throughout the year, and the peak month of births appears to vary by latitude. Seasonality in human birth rate appears to have largely decreased since the industrial revolution. Photoperiodism has also been demonstrated in other organisms besides plants and animals. The fungus Neurospora crassa as well as the dinoflagellate Lingulodinium polyedra and

3432-400: 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. Heteromorphic sex chromosomes were reported to occur in staminate individuals of dioecious "Kentucky" hemp, but were not found in pistillate individuals of

3536-473: Is not surprising that male-associated markers are relatively abundant. In dioecious plants where sex chromosomes have not been identified, markers for maleness indicate either the presence of sex chromosomes which have not been distinguished by cytological methods or that the marker is tightly linked to a gene involved in sex determination. Environmental sex determination is known to occur in a variety of species. Many researchers have suggested that sex in Cannabis

3640-399: Is possibly as a result of inbreeding . Cannabis has been described as having one of the most complicated mechanisms of sex determination among the dioecious plants. Many models have been proposed to explain sex determination in Cannabis . Based on studies of sex reversal in hemp , it was first reported by K. Hirata in 1924 that an XY sex-determination system is present. At the time,

3744-624: Is psychoactive. Since the early 1970s, Cannabis plants have been categorized by their chemical phenotype or "chemotype", based on the overall amount of THC produced, and on the ratio of THC to CBD. Although overall cannabinoid production is influenced by environmental factors, the THC/CBD ratio is genetically determined and remains fixed throughout the life of a plant. Non-drug plants produce relatively low levels of THC and high levels of CBD, while drug plants produce high levels of THC and low levels of CBD. When plants of these two chemotypes cross-pollinate,

3848-544: Is relatively uncommon in the plant kingdom, and a very low percentage of dioecious plant species have been determined to use the XY system. In most cases where the XY system is found it is believed to have evolved recently and independently. Since the 1920s, a number of sex determination models have been proposed for Cannabis . Ainsworth describes sex determination in the genus as using "an X/autosome dosage type". The question of whether heteromorphic sex chromosomes are indeed present

3952-412: Is reversed in the southern hemisphere (i.e., longest day is 21 December and shortest day is 21 June). Some long-day obligate plants are: Some long-day facultative plants are: Short-day (also called long-night) plants flower when the night lengths exceed their critical photoperiod. They cannot flower under short nights or if a pulse of artificial light is shone on the plant for several minutes during

4056-524: 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. McPartland's review finds the Schultes taxonomy inconsistent with prior work (protologs) and partly responsible for

4160-551: Is slightly larger than the X, but difficult to differentiate cytologically. More recently, Sakamoto and various co-authors have used random amplification of polymorphic DNA (RAPD) to isolate several genetic marker sequences that they name Male-Associated DNA in Cannabis (MADC), and which they interpret as indirect evidence of a male chromosome. Several other research groups have reported identification of male-associated markers using RAPD and amplified fragment length polymorphism . Ainsworth commented on these findings, stating, It

4264-460: Is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists about whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance,

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4368-474: Is the type species , and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed. In zoological usage, taxonomic names, including those of genera, are classified as "available" or "unavailable". Available names are those published in accordance with

4472-697: Is the most widespread variety, which is usually tall, laxly branched, and found in warm lowland regions. "Indica" designates shorter, bushier plants adapted to cooler climates and highland environments. "Ruderalis" is the informal name for the short plants that grow wild in Europe and Central Asia. Mapping the morphological concepts to scientific names in the Small 1976 framework, "Sativa" generally refers to C. sativa subsp. indica var. indica , "Indica" generally refers to C. sativa subsp. i. kafiristanica (also known as afghanica ), and "Ruderalis", being lower in THC,

4576-752: Is the one that can fall into C. sativa subsp. sativa . The three names fit in Schultes's framework better, if one overlooks its inconsistencies with prior work. Definitions of the three terms using factors other than morphology produces different, often conflicting results. Breeders, seed companies, and cultivators of drug type Cannabis often describe the ancestry or gross phenotypic characteristics of cultivars by categorizing them as "pure indica", "mostly indica", "indica/sativa", "mostly sativa", or "pure sativa". These categories are highly arbitrary, however: one "AK-47" hybrid strain has received both "Best Sativa" and "Best Indica" awards. Cannabis likely split from its closest relative, Humulus (hops), during

4680-399: Is the suite of physiological changes that occur in response to changes in day length. This allows animals to respond to a temporally changing environment associated with changing seasons as the earth orbits the sun. In 1920, W. W. Garner and H. A. Allard published their discoveries on photoperiodism and felt it was the length of daylight that was critical, but it was later discovered that

4784-621: The International Code of Zoological Nomenclature ; the earliest such name for any taxon (for example, a genus) should then be selected as the " valid " (i.e., current or accepted) name for the taxon in question. Consequently, there will be more available names than valid names at any point in time; which names are currently in use depending on the judgement of taxonomists in either combining taxa described under multiple names, or splitting taxa which may bring available names previously treated as synonyms back into use. "Unavailable" names in zoology comprise names that either were not published according to

4888-799: The International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names;

4992-455: The United States and Canada specifically named products of C. sativa as prohibited materials. Enterprising attorneys for the defense in a few drug busts argued that the seized Cannabis material may not have been C. sativa , and was therefore not prohibited by law. Attorneys on both sides recruited botanists to provide expert testimony. Among those testifying for the prosecution

5096-432: The canary depends on the photoperiod. In the spring, when the photoperiod increases (more daylight), the male canary's testes grow. As the testes grow, more androgens are secreted and song frequency increases. During autumn, when the photoperiod decreases (less daylight), the male canary's testes regress and androgen levels drop dramatically, resulting in decreased singing frequency. Not only is singing frequency dependent on

5200-404: The platypus belongs to the genus Ornithorhynchus although George Shaw named it Platypus in 1799 (these two names are thus synonyms ) . However, the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst in 1793. A name that means two different things is a homonym . Since beetles and platypuses are both members of the kingdom Animalia,

5304-495: The "modern" system of taxonomic nomenclature by Carl Linnaeus in 1753, who devised the system still in use for the naming of species. He considered the genus to be monotypic, having just a single species that he named Cannabis sativa L. Linnaeus was familiar with European hemp, which was widely cultivated at the time. This classification was supported by Christiaan Hendrik Persoon (in 1807), Lindley (in 1838) and De Candollee (in 1867). These first classification attempts resulted in

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5408-451: 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

5512-469: The French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or the scientific epithet) of a genus is also called the generic name ; in modern style guides and science, it is always capitalised. It plays a fundamental role in binomial nomenclature , the system of naming organisms , where it is combined with the scientific name of

5616-458: The Himalayan mountain range) might have enabled Cannabis gene pools to diverge before the onset of human intervention, resulting in speciation. It remains controversial whether sufficient morphological and genetic divergence occurs within the genus as a result of geographical or ecological isolation to justify recognition of more than one species. The genus Cannabis was first classified using

5720-561: The Middle East, use spread throughout the Islamic empire to North Africa. In 1545, cannabis spread to the western hemisphere where Spaniards imported it to Chile for its use as fiber. In North America, cannabis, in the form of hemp, was grown for use in rope, cloth and paper. Cannabinol (CBN) was the first compound to be isolated from cannabis extract in the late 1800s. Its structure and chemical synthesis were achieved by 1940, followed by some of

5824-545: The XY system was the only known system of sex determination. The X:A system was first described in Drosophila spp in 1925. Soon thereafter, Schaffner disputed Hirata's interpretation, and published results from his own studies of sex reversal in hemp, concluding that an X:A system was in use and that furthermore sex was strongly influenced by environmental conditions. Since then, many different types of sex determination systems have been discovered, particularly in plants. Dioecy

5928-442: The base for higher taxonomic ranks, such as the family name Canidae ("Canids") based on Canis . However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is Carnivora ("Carnivores"). The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of

6032-399: The brain. Photoperiod can affect insects at different life stages, serving as an environmental cue for physiological processes such as diapause induction and termination, and seasonal morphs. In the water strider Aquarius paludum , for instance, photoperiod conditions during nymphal development have been shown to trigger seasonal changes in wing frequency and also induce diapause, although

6136-465: The choice to use the term "Indian hemp" (linked to the plant's history in India), hence naming the species as indica. Additional Cannabis species were proposed in the 19th century, including strains from China and Vietnam (Indo-China) assigned the names Cannabis chinensis Delile, and Cannabis gigantea Delile ex Vilmorin. However, many taxonomists found these putative species difficult to distinguish. In

6240-468: The cultivar. Dioecious varieties are preferred for drug production, where the fruits (produced by female flowers) are used. Dioecious varieties are also preferred for textile fiber production, whereas monoecious varieties are preferred for pulp and paper production. It has been suggested that the presence of monoecy can be used to differentiate licit crops of monoecious hemp from illicit drug crops, but sativa strains often produce monoecious individuals, which

6344-453: The deepest point of the notch. Tiny samples of Cannabis also can be identified with precision by microscopic examination of leaf cells and similar features, requiring special equipment and expertise. All known strains of Cannabis are wind-pollinated and the fruit is an achene . Most strains of Cannabis are short day plants , with the possible exception of C. sativa subsp. sativa var. spontanea (= C. ruderalis ), which

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6448-594: The early Miocene , around 19.6 million years ago. Cannabis was widely distributed over Asia by the Late Pleistocene. The oldest known Cannabis in South Asia dates to around 32,000 years ago. Cannabis is used for a wide variety of purposes. According to genetic and archaeological evidence, cannabis was first domesticated about 12,000 years ago in East Asia during the early Neolithic period. The use of cannabis as

6552-526: The early 20th century, the single-species concept (monotypic classification) was still widely accepted, except in the Soviet Union , where Cannabis continued to be the subject of active taxonomic study. The name Cannabis indica was listed in various Pharmacopoeias , and was widely used to designate Cannabis suitable for the manufacture of medicinal preparations. In 1924, Russian botanist D.E. Janichevsky concluded that ruderal Cannabis in central Russia

6656-531: The felt coverings, throw it upon the red-hot stones; immediately it smokes, and gives out such a vapour as no Greek vapour-bath can exceed; the Scyths, delighted, shout for joy." Classical Greeks and Romans also used cannabis. In China, the psychoactive properties of cannabis are described in the Shennong Bencaojing (3rd century AD). Cannabis smoke was inhaled by Daoists , who burned it in incense burners. In

6760-468: The first preclinical research studies to determine the effects of individual cannabis-derived compounds in vivo. Globally, in 2013, 60,400 kilograms of cannabis were produced legally . Genus The composition of a genus is determined by taxonomists . The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including

6864-446: The form "author, year" in zoology, and "standard abbreviated author name" in botany. Thus in the examples above, the genus Canis would be cited in full as " Canis Linnaeus, 1758" (zoological usage), while Hibiscus , also first established by Linnaeus but in 1753, is simply " Hibiscus L." (botanical usage). Each genus should have a designated type , although in practice there is a backlog of older names without one. In zoology, this

6968-727: The generic name (or its abbreviated form) still forms the leading portion of the scientific name, for example, Canis lupus lupus for the Eurasian wolf subspecies, or as a botanical example, Hibiscus arnottianus ssp. immaculatus . Also, as visible in the above examples, the Latinised portions of the scientific names of genera and their included species (and infraspecies, where applicable) are, by convention, written in italics . The scientific names of virus species are descriptive, not binomial in form, and may or may not incorporate an indication of their containing genus; for example,

7072-432: The idea that a newly defined genus should fulfill these three criteria to be descriptively useful: Moreover, genera should be composed of phylogenetic units of the same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but

7176-628: The largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles , which have about 1180 genera,

7280-484: The length of the night was the controlling factor. Photoperiodic flowering plants are classified as long-day plants or short-day plants even though night is the critical factor because of the initial misunderstanding about daylight being the controlling factor. Along with long-day plants and short-day plants, there are plants that fall into a "dual-day length category". These plants are either long-short-day plants (LSDP) or short-long-day plants (SLDP). LSDPs flower after

7384-557: The light input through the RHT and by innate circadian rhythms . This hormonal signal, combined with outputs from the SCN inform the rest of the body about the time of day, and the length of time that melatonin is secreted is how the time of year is perceived. Many mammals, particularly those inhabiting temperate and polar regions, exhibit a remarkable degree of seasonality in response to changes in daylight hours(photoperiod). This seasonality manifests in

7488-432: The lizard genus Anolis has been suggested to be broken down into 8 or so different genera which would bring its ~400 species to smaller, more manageable subsets. Photoperiodism Photoperiod is the change of day length around the seasons. The rotation of the earth around its axis produces 24 hour changes in light (day) and dark (night) cycles on earth. The length of the light and dark in each phase varies across

7592-478: The loss of leaves. Artificial lighting can be used to induce extra-long days. Long-day plants flower when the night length falls below their critical photoperiod. These plants typically flower during late spring or early summer as days are getting longer. In the northern hemisphere, the longest day of the year (summer solstice) is on or about 21 June. After that date, days grow shorter (i.e. nights grow longer) until 21 December (the winter solstice ). This situation

7696-528: The mid Oligocene , around 27.8 million years ago according to molecular clock estimates. The centre of origin of Cannabis is likely in the northeastern Tibetan Plateau . The pollen of Humulus and Cannabis are very similar and difficult to distinguish. The oldest pollen thought to be from Cannabis is from Ningxia , China, on the boundary between the Tibetan Plateau and the Loess Plateau , dating to

7800-403: The most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus , contains over 3,000 species. Which species are assigned to a genus

7904-428: The name could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800. However, a genus in one kingdom is allowed to bear a scientific name that is in use as a generic name (or the name of a taxon in another rank) in a kingdom that is governed by a different nomenclature code. Names with the same form but applying to different taxa are called "homonyms". Although this

8008-470: The night; they require a continuous period of darkness before floral development can begin. Natural nighttime light, such as moonlight or lightning, is not of sufficient brightness or duration to interrupt flowering. Short-day plants flower as days grow shorter (and nights grow longer) after September 21st in the northern hemisphere, which is during summer or fall. The length of the dark period required to induce flowering differs among species and varieties of

8112-488: The other putative taxa. A 2020 analysis of single-nucleotide polymorphisms reports five clusters of cannabis , roughly corresponding to hemps (including folk "Ruderalis") folk "Indica" and folk "Sativa". Despite advanced analytical techniques, much of the cannabis used recreationally is inaccurately classified. One laboratory at the University of British Columbia found that Jamaican Lamb's Bread, claimed to be 100% sativa,

8216-432: The photoperiod but the song repertoire is also. The long photoperiod of spring results in a greater song repertoire. Autumn's shorter photoperiod results in a reduction in song repertoire. These behavioral photoperiod changes in male canaries are caused by changes in the song center of the brain. As the photoperiod increases, the high vocal center (HVC) and the robust nucleus of the archistriatum (RA) increase in size. When

8320-429: The photoperiod decreases, these areas of the brain regress. In mammals, daylength is registered in the suprachiasmatic nucleus (SCN), which is informed by retinal light-sensitive ganglion cells , which are not involved in vision. The information travels through the retinohypothalamic tract (RHT). In most species the hormone melatonin is produced by the pineal gland only during the hours of darkness, influenced by

8424-415: The photoreceptors are in regards to determining day-length. Modern biologists believe that it is the coincidence of the active forms of phytochrome or cryptochrome, created by light during the daytime, with the rhythms of the circadian clock that allows plants to measure the length of the night. Other than flowering, photoperiodism in plants includes the growth of stems or roots during certain seasons and

8528-438: The physiological reaction of organisms to the length of light or a dark period. It occurs in plants and animals . Plant photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light and dark periods. They are classified under three groups according to the photoperiods: short-day plants, long-day plants, and day-neutral plants. In animals photoperiodism (sometimes called seasonality)

8632-403: The plants in the first filial (F 1 ) generation have an intermediate chemotype and produce intermediate amounts of CBD and THC. Female plants of this chemotype may produce enough THC to be utilized for drug production. Whether the drug and non-drug, cultivated and wild types of Cannabis constitute a single, highly variable species, or the genus is polytypic with more than one species, has been

8736-642: The popular usage. Molecular analytical techniques developed in the late 20th century are being applied to questions of taxonomic classification. This has resulted in many reclassifications based on evolutionary systematics . Several studies of random amplified polymorphic DNA (RAPD) and other types of genetic markers have been conducted on drug and fiber strains of Cannabis , primarily for plant breeding and forensic purposes. Dutch Cannabis researcher E.P.M. de Meijer and coworkers described some of their RAPD studies as showing an "extremely high" degree of genetic polymorphism between and within populations, suggesting

8840-408: The position of the second notch down. 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 pass tangentially to the notch, but often will pass by at a small distance; when the latter happens a spur vein (or occasionally two) branches off and joins the leaf margin at

8944-526: The provisions of the ICZN Code, e.g., incorrect original or subsequent spellings, names published only in a thesis, and generic names published after 1930 with no type species indicated. According to "Glossary" section of the zoological Code, suppressed names (per published "Opinions" of the International Commission of Zoological Nomenclature) remain available but cannot be used as the valid name for

9048-454: The red-to far-red ratio in Arabidopsis can alter flowering. They discovered that plants tend to flower later when exposed to more red light, proving that red light is inhibitory to flowering. Other experiments have proven this by exposing plants to extra red-light in the middle of the night. A short-day plant will not flower if light is turned on for a few minutes in the middle of the night and

9152-528: The rise of craft cannabis growers in Canada should ensure quality, experimentation/research, and diversification of strains among private-sector producers. The scientific debate regarding taxonomy has had little effect on the terminology in widespread use among cultivators and users of drug-type Cannabis . Cannabis aficionados recognize three distinct types based on such factors as morphology, native range , aroma, and subjective psychoactive characteristics. "Sativa"

9256-407: The same plant.) Subdioecy (the occurrence of monoecious individuals and dioecious individuals within the same population) is widespread. Many populations have been described as sexually labile. As a result of intensive selection in cultivation , Cannabis exhibits many sexual phenotypes that can be described in terms of the ratio of female to male flowers occurring in the individual, or typical in

9360-427: 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. According to other researchers, no modern karyotype of Cannabis had been published as of 1996. Proponents of the XY system state that Y chromosome

9464-423: The season of the year, is vital to many animals. A number of biological and behavioural changes are dependent on this knowledge. Together with temperature changes, photoperiod provokes changes in the color of fur and feathers, migration , entry into hibernation , sexual behaviour , and even the resizing of organs. In insects , sensitivity to photoperiod has been proven to be initiated by photoreceptors located in

9568-401: The seasons due to the tilt of the earth around its axis. The photoperiod defines the length of the light, for example a summer day the length of light could be 16 hours while the dark is 8 hours, whereas a winter day the length of day could be 8 hours, whereas the dark is 16 hours. Importantly, the seasons are different in the northern hemisphere than the southern hemisphere. Photoperiodism is

9672-475: The shade, and this converts phytochrome from P fr to its inactive form, P r , inhibiting germination. This system of P fr to P r conversion allows the plant to sense when it is night and when it is day. P fr can also be converted back to P r by a process known as dark reversion, where long periods of darkness trigger the conversion of P fr . This is important in regards to plant flowering. Experiments by Halliday et al. showed that manipulations of

9776-497: The specific name particular to the wolf. A botanical example would be Hibiscus arnottianus , a particular species of the genus Hibiscus native to Hawaii. The specific name is written in lower-case and may be followed by subspecies names in zoology or a variety of infraspecific names in botany . When the generic name is already known from context, it may be shortened to its initial letter, for example, C. lupus in place of Canis lupus . Where species are further subdivided,

9880-412: The standard format for a species name comprises the generic name, indicating the genus to which the species belongs, followed by the specific epithet, which (within that genus) is unique to the species. For example, the gray wolf 's scientific name is Canis lupus , with Canis ( Latin for 'dog') being the generic name shared by the wolf's close relatives and lupus (Latin for 'wolf') being

9984-403: The taxon is termed a synonym ; some authors also include unavailable names in lists of synonyms as well as available names, such as misspellings, names previously published without fulfilling all of the requirements of the relevant nomenclatural code, and rejected or suppressed names. A particular genus name may have zero to many synonyms, the latter case generally if the genus has been known for

10088-451: The threshold critical day lengths for the determination of both traits diverged by about an hour. In Gerris buenoi , another water strider species, photoperiod has also been shown to be the cause of wing polyphenism , although the specific daylengths changed between species, suggesting that phenotypic plasticity in response to photoperiod has evolved even between relatively closely related species. The singing frequency of birds such as

10192-479: The two C. sativa subspecies into 13 varieties, including four distinct groups within subspecies culta . However, they did not divide C. indica into subspecies or varieties. Zhukovski, in 1950, also proposed a two-species system, but with C. sativa L. and C. ruderalis . In the 1970s, the taxonomic classification of Cannabis took on added significance in North America. Laws prohibiting Cannabis in

10296-462: The use of cannabis by observing Scythian funerals, during which cannabis was consumed. In Akkadian , cannabis was known as qunubu ( 𐎯𐎫𐎠𐎭𐏂 ). The word was adopted in to the Hebrew language as qaneh bosem ( קָנֶה בֹּשׂם ). Cannabis is an annual , dioecious , flowering herb . The leaves are palmately compound or digitate , with serrate leaflets . The first pair of leaves usually have

10400-566: The values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda , with 151,697 ± 33,160 accepted genus names, of which 114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up

10504-429: The virus species " Salmonid herpesvirus 1 ", " Salmonid herpesvirus 2 " and " Salmonid herpesvirus 3 " are all within the genus Salmonivirus ; however, the genus to which the species with the formal names " Everglades virus " and " Ross River virus " are assigned is Alphavirus . As with scientific names at other ranks, in all groups other than viruses, names of genera may be cited with their authorities, typically in

10608-405: Was Dr. Ernest Small, while Dr. Richard E. Schultes and others testified for the defense. The botanists engaged in heated debate (outside of court), and both camps impugned the other's integrity. The defense attorneys were not often successful in winning their case, because the intent of the law was clear. In 1976, Canadian botanist Ernest Small and American taxonomist Arthur Cronquist published

10712-425: Was considered smaller, by Lamarck. Also, woodier stems, alternate ramifications of the branches, narrow leaflets, and a villous calyx in the female flowers were characteristics noted by the botanist. In 1843, William O’Shaughnessy, used "Indian hemp ( C. indica )" in a work title. The author claimed that this choice wasn't based on a clear distinction between C. sativa and C. indica , but may have been influenced by

10816-499: Was in fact almost 100% indica (the opposite strain). Legalization of cannabis in Canada (as of 17 October 2018) may help spur private-sector research, especially in terms of diversification of strains. It should also improve classification accuracy for cannabis used recreationally. Legalization coupled with Canadian government (Health Canada) oversight of production and labelling will likely result in more—and more accurate—testing to determine exact strains and content. Furthermore,

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