Editing Cannabis (section)

==Taxonomy==
[[File:Cannabis sativa leaf diagnostic venation 2012 01 23 0829 c.jpg|thumb|Underside of ''[[Cannabis sativa]]'' leaf, showing diagnostic venation]]
The genus ''Cannabis'' was formerly placed in the [[Urtica|nettle]] family ([[Urticaceae]]) or [[mulberry]] family ([[Moraceae]]), and later, along with the genus ''[[Humulus]]'' ([[hops]]), in a separate family, the hemp family (Cannabaceae [[sensu stricto]]).<ref name=schultes2001a>{{cite book | vauthors = Schultes RE, Hofmann A, Rätsch C | date = 2001 | chapter = The nectar of delight. | title = Plants of the Gods | edition = 2nd | publisher = Healing Arts Press | location = Rochester, Vermont | pages = 92–101 | isbn = 978-0-89281-979-9 }}</ref> Recent [[phylogenetic]] studies based on [[cpDNA]] [[restriction site]] analysis and [[DNA sequencing|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]].<ref name=song2001>{{cite journal|doi=10.1007/s006060170041|title=Further evidence for paraphyly of the Celtidaceae from the chloroplast gene mat K|year=2001| vauthors = Song BH, Wang XQ, Li FZ, Hong DY |journal=Plant Systematics and Evolution|volume=228|issue=1–2|pages=107–15|bibcode=2001PSyEv.228..107S |s2cid=45337406}}</ref><ref name=sytsma2002>{{cite journal | vauthors = Sytsma KJ, Morawetz J, Pires JC, Nepokroeff M, Conti E, Zjhra M, Hall JC, Chase MW | s2cid = 207690258 | display-authors = 6 | title = Urticalean rosids: circumscription, rosid ancestry, and phylogenetics based on rbcL, trnL-F, and ndhF sequences | journal = American Journal of Botany | volume = 89 | issue = 9 | pages = 1531–46 | date = September 2002 | pmid = 21665755 | doi = 10.3732/ajb.89.9.1531 | doi-access =  }}</ref>

Various types of ''Cannabis'' have been described, and variously classified as [[species]], [[subspecies]], or [[Variety (biology)|varieties]]:<ref name="small1975b">{{cite journal | vauthors = Small E | title = American law and the species problem in Cannabis: science and semantics | journal = Bulletin on Narcotics | volume = 27 | issue = 3 | pages = 1–20 | year = 1975 | pmid = 1041693 }}</ref>
* plants cultivated for fiber and seed production, described as low-intoxicant, non-drug, or fiber types.
* plants cultivated for drug production, described as high-intoxicant or drug types.
* escaped, hybridised, or wild forms of either of the above types.

''Cannabis'' plants produce 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,<ref>{{cite web|url=http://medicalmarijuana.procon.org/view.answers.php?questionID=000636|title=What chemicals are in marijuana and its byproducts?|publisher=ProCon.org|year=2009|access-date=13 January 2013|archive-date=20 January 2013|archive-url=https://web.archive.org/web/20130120030619/http://medicalmarijuana.procon.org/view.answers.php?questionID=000636|url-status=live}}</ref> and at least 85 different cannabinoids have been isolated from the plant.<ref>{{cite journal | vauthors = El-Alfy AT, Ivey K, Robinson K, Ahmed S, Radwan M, Slade D, Khan I, ElSohly M, Ross S | display-authors = 6 | title = Antidepressant-like effect of delta9-tetrahydrocannabinol and other cannabinoids isolated from Cannabis sativa L | journal = Pharmacology, Biochemistry, and Behavior | volume = 95 | issue = 4 | pages = 434–42 | date = June 2010 | pmid = 20332000 | pmc = 2866040 | doi = 10.1016/j.pbb.2010.03.004 }}</ref> The two cannabinoids usually produced in greatest abundance are [[cannabidiol]] (CBD) and/or Δ<sup>9</sup>-[[tetrahydrocannabinol]] (THC), but only THC is psychoactive.<ref name="pmid19204413">{{cite journal | vauthors = Ahrens J, Demir R, Leuwer M, de la Roche J, Krampfl K, Foadi N, Karst M, Haeseler G | display-authors = 6 | title = The nonpsychotropic cannabinoid cannabidiol modulates and directly activates alpha-1 and alpha-1-Beta glycine receptor function | journal = Pharmacology | volume = 83 | issue = 4 | pages = 217–22 | year = 2009 | pmid = 19204413 | doi = 10.1159/000201556 | s2cid = 13508856 | url = https://www.karger.com/Article/PDF/000201556 | access-date = 18 May 2019 | archive-date = 18 May 2019 | archive-url = https://web.archive.org/web/20190518161406/https://www.karger.com/Article/PDF/000201556 | url-status = live }}</ref> 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.<ref name="small1973a">{{cite journal | vauthors = Small E, Beckstead HD | title = Common cannabinoid phenotypes in 350 stocks of Cannabis | journal = Lloydia | volume = 36 | issue = 2 | pages = 144–65 | date = June 1973 | pmid = 4744553 }}</ref> 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.<ref name="meijer2003a">{{cite journal | vauthors = de Meijer EP, Bagatta M, Carboni A, Crucitti P, Moliterni VM, Ranalli P, Mandolino G | title = The inheritance of chemical phenotype in Cannabis sativa L | journal = Genetics | volume = 163 | issue = 1 | pages = 335–46 | date = January 2003 | doi = 10.1093/genetics/163.1.335 | pmid = 12586720 | pmc = 1462421 }}</ref> 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, the plants in the first filial (F<sub>1</sub>) 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.<ref name=small1973a/><ref name="hillig2004a">{{cite journal | vauthors = Hillig KW, Mahlberg PG | s2cid = 32469533 | title = A chemotaxonomic analysis of cannabinoid variation in Cannabis (Cannabaceae) | journal = American Journal of Botany | volume = 91 | issue = 6 | pages = 966–75 | date = June 2004 | pmid = 21653452 | doi = 10.3732/ajb.91.6.966 | doi-access = free | bibcode = 2004AmJB...91..966H }}</ref>

[[File:Cannabis-vegetative-growth-00003.jpg|thumb|Top of ''Cannabis'' plant in vegetative growth stage]]
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 a subject of debate for well over two centuries. This is a contentious issue because there is no universally accepted definition of a [[species]].<ref name="small1979a">{{cite book | vauthors = Small E | date = 1979 | chapter = Fundamental aspects of the species problem in biology. | title = The Species Problem in Cannabis | volume = 1 | publisher = Science. Corpus Information Services | location = Toronto, Canada | pages = 5–63 | isbn = 978-0-919217-11-9 }}</ref> 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."<ref name="glossary">{{cite book | vauthors = Rieger R, Michaelis A, Green MM | date = 1991 | title = Glossary of Genetics | edition = 5th | publisher = Springer-Verlag | pages = 458–459 | isbn = 978-0-387-52054-4 }}</ref> 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.<ref name=glossary/> [[Reproductive isolation|Physiological barriers to reproduction]] are not known to occur within ''Cannabis'', and plants from widely divergent sources are interfertile.<ref name="small1972a"/> However, physical barriers to gene exchange (such as the Himalayan mountain range) might have enabled ''Cannabis'' gene pools to diverge before the onset of human intervention, resulting in speciation.<ref name="hillig2005a">{{cite journal|doi=10.1007/s10722-003-4452-y|title=Genetic evidence for speciation in Cannabis (Cannabaceae)|year=2005| vauthors = Hillig KW |journal=Genetic Resources and Crop Evolution|volume=52|issue=2|pages=161–80|bibcode=2005GRCEv..52..161H |s2cid=24866870}}</ref> 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.<ref name="small1975a">{{cite journal| vauthors = Small E |year=1975|url=http://www.botany.org/PlantScienceBulletin/psb-1975-21-3.php|title=On toadstool soup and legal species of marihuana|journal=Plant Science Bulletin|volume=21|issue=3|pages=34–9|access-date=28 September 2006|archive-date=27 September 2006|archive-url=https://web.archive.org/web/20060927191824/http://www.botany.org/PlantScienceBulletin/psb-1975-21-3.php|url-status=live}}</ref><ref name="emboden1981a">{{cite journal | vauthors = Emboden WA | title = The genus Cannabis and the correct use of taxonomic categories | journal = Journal of Psychoactive Drugs | volume = 13 | issue = 1 | pages = 15–21 | year = 1981 | pmid = 7024491 | doi = 10.1080/02791072.1981.10471446 }}</ref><ref name="schultes1980a">{{cite book | vauthors = Schultes RE, Hofmann A | date = 1980 | title = Botany and Chemistry of Hallucinogens | publisher = C. C. Thomas | location = Springfield, Illinois | pages = 82–116 | isbn = 978-0-398-03863-2 }}</ref>

===Early classifications===
[[File:Cannab2 new.png|thumb|upright|Relative size of varieties of ''Cannabis'']]

The genus ''Cannabis'' was first [[Scientific classification|classified]] using the "modern" system of taxonomic [[Binomial nomenclature|nomenclature]] by [[Carl Linnaeus]] in 1753, who devised the system still in use for the naming of species.<ref name="linnaeus1753">{{cite book | vauthors = Linnaeus C | orig-date = 1753 | title = Species Plantarum | volume = 2 | page = 1027 | edition = Facsimile | date = 1957–1959 | publisher = Ray SocietyLondon, U.K. (originally Salvius, Stockholm) }}</ref> He considered the genus to be monotypic, having just a single species that he named ''Cannabis sativa'' L.<ref group="a">"L." stands for Linnaeus, and indicates the authority who first named the species</ref> 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 a four group division:<ref name=":1">{{Cite journal |last1=Lapierre |first1=Éliana |last2=Monthony |first2=Adrian S. |last3=Torkamaneh |first3=Davoud |date=2023-08-01 |title=Genomics-based taxonomy to clarify cannabis classification |journal=Genome |language=en |volume=66 |issue=8 |pages=202–211 |doi=10.1139/gen-2023-0005 |issn=0831-2796|doi-access=free |pmid=37163765 }}</ref>

* Kif (southern hemp - psychoactive)
* Vulgaris (intermediate - psychoactive and fiber)
* Pedemontana (northern hemp - fiber)
* Chinensis (northern hemp - fiber)

In 1785, evolutionary biologist [[Jean-Baptiste de Lamarck]] published a description of a second species of ''Cannabis'', which he named ''Cannabis indica'' Lam.<ref name="lamarck1785">{{cite book | vauthors = de Lamarck JB | date = 1785 | title = Encyclopédie Méthodique de Botanique | volume = 1 | issue = 2 | location = Paris, France | pages = 694–695 }}</ref> 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 [[Psychoactive drug|inebriant]]. Also, ''C. indica'' 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.<ref name=":1" />

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 the choice to use the term "Indian hemp" (linked to the plant's history in India), hence naming the species as ''indica.<ref name=":1" />''

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.<ref name="small1976a">{{cite journal| vauthors = Small E, Cronquist A |year=1976|title=A Practical and Natural Taxonomy for Cannabis|journal=Taxon|volume=25|issue=4|pages=405–35|jstor=1220524|doi=10.2307/1220524|bibcode=1976Taxon..25..405S }}</ref> However, many taxonomists found these putative species difficult to distinguish. In 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 [[Pharmacopoeia]]s, and was widely used to designate ''Cannabis'' suitable for the manufacture of medicinal preparations.<ref name="winek1977">{{cite journal | vauthors = Winek CL | title = Some historical aspects of marijuana | journal = Clinical Toxicology | volume = 10 | issue = 2 | pages = 243–53 | year = 1977 | pmid = 322936 | doi = 10.3109/15563657708987969 }}</ref>

===20th century===
{{Further|Feral cannabis}}
[[File:Cannabis ruderalis.jpg|thumb|left|''[[Cannabis ruderalis]]'']]
In 1924, Russian botanist D.E. Janichevsky concluded that [[ruderal]] ''Cannabis'' in central Russia is either a variety of ''C.&nbsp;sativa'' or a separate species, and proposed ''C.&nbsp;sativa'' L. var. ''ruderalis'' Janisch, and ''Cannabis ruderalis'' Janisch, as alternative names.<ref name=small1975b/> In 1929, renowned plant explorer [[Nikolai Vavilov]] assigned wild or feral populations of ''Cannabis'' in Afghanistan to ''C.&nbsp;indica'' Lam. var. ''kafiristanica'' Vav., and ruderal populations in Europe to ''C.&nbsp;sativa'' L. var. ''spontanea'' Vav.<ref name="hillig2004a"/><ref name=small1976a/> Vavilov, in 1931, proposed a three species system, independently reinforced by Schultes ''et al'' (1975)<ref>{{Citation |last1=Schultes |first1=Richard Evans |title=Cannabis: An Example of Taxonomic Neglect |date=1975-12-31 |work=Cannabis and Culture |pages=21–38 |editor-last=Rubin |editor-first=Vera |url=https://www.degruyter.com/document/doi/10.1515/9783110812060.21/html |access-date=2024-07-22 |publisher=De Gruyter Mouton |doi=10.1515/9783110812060.21 |isbn=978-90-279-7669-7 |last2=Klein |first2=William M. |last3=Plowman |first3=Timothy |last4=Lockwood |first4=Tom E.}}</ref> and Emboden (1974):<ref>{{Cite journal |last=Emboden |first=William A. |date=1974 |title=Cannabis — a polytypic genus |url=http://link.springer.com/10.1007/BF02861427 |journal=Economic Botany |language=en |volume=28 |issue=3 |pages=304–310 |doi=10.1007/BF02861427 |bibcode=1974EcBot..28..304E |issn=0013-0001}}</ref> ''C. sativa'', ''C. indica'' and ''C. ruderalis.<ref name=":1" />''

In 1940, Russian botanists Serebriakova and Sizov proposed a complex poly-species classification in which they also recognized ''C.&nbsp;sativa'' and ''C.&nbsp;indica'' as separate species. Within ''C.&nbsp;sativa'' they recognized two subspecies: ''C.&nbsp;sativa'' L. subsp. ''culta'' Serebr. (consisting of cultivated plants), and ''C.&nbsp;sativa'' L. subsp. ''spontanea'' (Vav.) Serebr. (consisting of wild or feral plants). Serebriakova and Sizov split the two ''C.&nbsp;sativa'' subspecies into 13 varieties, including four distinct groups within subspecies ''culta''. However, they did not divide ''C.&nbsp;indica'' into subspecies or varieties.<ref name="small1975b" /><ref name="serebriakova1940">{{cite book | vauthors = Serebriakova TY, Sizov IA | date = 1940 | chapter = Cannabinaceae Lindl. | veditors = Vavilov NI | title = Kulturnaya Flora SSSR | volume = 5 | location = Moscow-Leningrad, USSR | pages = 1–53 | language = Russian }}</ref><ref>{{Cite journal |last1=Koren |first1=Anamarija |last2=Sikora |first2=Vladimir |last3=Kiprovski |first3=Biljana |last4=Brdar-Jokanović |first4=Milka |last5=Aćimović |first5=Milica |last6=Konstantinović |first6=Bojan |last7=Latković |first7=Dragana |date=2020 |title=Controversial taxonomy of hemp |url=https://doiserbia.nb.rs/Article.aspx?ID=0534-00122001001K |journal=Genetika |volume=52 |issue=1 |pages=1–13 |doi=10.2298/gensr2001001k}}</ref> Zhukovski, in 1950, also proposed a two-species system, but with ''C. sativa'' L. and ''C. ruderalis''.<ref>Zhukovskii, P.M. (1971) ''Cultivated plants and their wild relatives''. 3rd ed. Leningrad, USSR, Kolos.</ref>

In the 1970s, the taxonomic classification of ''Cannabis'' took on added significance in North America. Laws prohibiting ''Cannabis'' in the [[United States]] and [[Canada]] specifically named products of ''C.&nbsp;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.&nbsp;sativa'', and was therefore not prohibited by law. Attorneys on both sides recruited botanists to provide expert testimony. Among those testifying for the prosecution was Dr. Ernest Small, while [[Richard E. Schultes|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.<ref name=small1975a/><ref name=emboden1981a/> The defense attorneys were not often successful in winning their case, because the intent of the law was clear.<ref name="watts2006">{{cite journal | vauthors = Watts G | title = Cannabis confusions | journal = BMJ | volume = 332 | issue = 7534 | pages = 175–6 | date = January 2006 | pmid = 16424501 | pmc = 1336775 | doi = 10.1136/bmj.332.7534.175 }}</ref> 
[[File:Cannabis_taxonomy_theories.jpg|center|thumb|531x531px|Three theories of classification for ''Cannabis''. From left to right, monotypic with three subspecies (A), polytypic consisting of up to three species (B), and single phenotypically diverse species (C).]]In 1976, Canadian botanist Ernest Small<ref name="smallbiography">[http://pubs.nrc-cnrc.gc.ca/cgi-bin/rp/rp2_gene_e?mlist-authors-small_e.html Ernest Small (biography)] {{webarchive|url=https://web.archive.org/web/20070211135642/http://pubs.nrc-cnrc.gc.ca/cgi-bin/rp/rp2_gene_e?mlist-authors-small_e.html |date=11 February 2007 }}. National Research Council Canada. Retrieved on 23 February 2007</ref> and American taxonomist [[Arthur Cronquist]] published 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:
* ''C. sativa'' L. subsp. ''sativa'', presumably [[Artificial selection|selected]] for traits that enhance fiber or seed production.
** ''C. sativa'' L. subsp. ''sativa'' var. ''sativa'', domesticated variety.
** ''C. sativa'' L. subsp. ''sativa'' var. ''spontanea'' Vav., wild or escaped variety.
* ''C. sativa'' L. subsp. ''indica'' (Lam.) Small & Cronq.,<ref name=small1976a/> primarily selected for drug production.
** ''C. sativa'' L. subsp. ''indica'' var. ''indica'', domesticated variety.
** ''C. sativa'' subsp. ''indica'' var. ''kafiristanica'' (Vav.) Small & Cronq, wild or escaped variety.

This classification was based on several factors including interfertility, chromosome uniformity, chemotype, and numerical analysis of [[phenotypic]] characters.<ref name=small1973a/><ref name=small1976a/><ref name="small1976b">{{cite journal| vauthors = Small E, Jui PY, Lefkovitch LP |year=1976|title=A Numerical Taxonomic Analysis of Cannabis with Special Reference to Species Delimitation|journal=Systematic Botany|volume=1|issue=1|pages=67–84|jstor=2418840|doi=10.2307/2418840|bibcode=1976SysBo...1...67S }}</ref>

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 [[morphology (biology)|morphological]] differences exist that support recognition of at least three species, ''C.&nbsp;sativa'', ''C.&nbsp;indica'', and ''C.&nbsp;ruderalis.''<ref name="schultes1974a">{{cite journal | vauthors = Schultes RE, Klein WM, Plowman T, Lockwood TE | year = 1974 | title = ''Cannabis'': an example of taxonomic neglect | journal = Harvard University Botanical Museum Leaflets | volume = 23 |issue=9 | pages = 337–367 |doi=10.5962/p.168565 | doi-access = free }}</ref><ref name="anderson1974a">[http://www.bio.fsu.edu/faculty-anderson.php Anderson, L. C.] {{Webarchive|url=https://web.archive.org/web/20090308011913/http://www.bio.fsu.edu/faculty-anderson.php |date=8 March 2009 }} 1974. A study of systematic wood anatomy in ''Cannabis''. ''Harvard University Botanical Museum Leaflets'' '''24''': 29–36. Retrieved on 23 February 2007</ref><ref name="anderson1980a">[http://www.bio.fsu.edu/faculty-anderson.php Anderson, L. C.] {{Webarchive|url=https://web.archive.org/web/20090308011913/http://www.bio.fsu.edu/faculty-anderson.php |date=8 March 2009 }} 1980. Leaf variation among ''Cannabis'' species from a controlled garden. ''Harvard University Botanical Museum Leaflets'' '''28''': 61–69. Retrieved on 23 February 2007</ref><ref name=emboden1974a>{{cite journal|doi=10.1007/BF02861427|title=Cannabis — a polytypic genus|year=1974| vauthors = Emboden WA |journal=Economic Botany|volume=28|issue=3|pages=304–310|bibcode=1974EcBot..28..304E |s2cid=35358047}}</ref> For Schultes, this was a reversal of his previous interpretation that ''Cannabis'' is monotypic, with only a single species.<ref name="schultes1970a">{{cite book | vauthors = Schultes RE | date = 1970 | chapter = Random thoughts and queries on the botany of ''Cannabis'' | veditors = Joyce CR, Curry SH | title = The Botany and Chemistry of Cannabis | publisher = J. & A. Churchill | location = London | pages = 11–38 }}</ref> According to Schultes' and Anderson's descriptions, ''C.&nbsp;sativa'' is tall and laxly branched with relatively narrow leaflets, ''C.&nbsp;indica'' is shorter, conical in shape, and has relatively wide leaflets, and ''C.&nbsp;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.<ref name="clarke2005a">[https://web.archive.org/web/20110727002712/http://www.norml.org.nz/modules.php?name=News&file=print&sid=588 Interview with Robert Connell Clarke]. 1 January 2005. NORML, New Zealand. Retrieved on 19 February 2007</ref> McPartland's review finds the Schultes taxonomy inconsistent with prior work (protologs) and partly responsible for the popular usage.<ref name="pmid30426073"/>

===Continuing research===
[[Molecular biology|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 [[History of plant systematics#Evolutionary systematics|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.<ref name="faeti1996a">{{cite journal | vauthors = Mandolino G, Carboni A, Forapani S, Faeti V, Ranalli P |doi=10.1007/s001220051043|title=Identification of DNA markers linked to the male sex in dioecious hemp (Cannabis sativa L.)|year=1999 |journal=Theoretical and Applied Genetics|volume=98|pages=86–92|s2cid=26011527}}</ref><ref name="forapani2001a">{{cite journal|doi=10.2135/cropsci2001.1682|title=Comparison of Hemp Varieties Using Random Amplified Polymorphic DNA Markers|year=2001| vauthors = Forapani S, Carboni A, Paoletti C, Moliterni VM, Ranalli P, Mandolino G |s2cid=29448044|journal=Crop Science|volume=41|issue=6|page=1682|url=http://pdfs.semanticscholar.org/2e7d/f4b5dd7992dd5ad04d3098aae531fd2d7a28.pdf |archive-url=https://web.archive.org/web/20220311032503/http://pdfs.semanticscholar.org/2e7d/f4b5dd7992dd5ad04d3098aae531fd2d7a28.pdf |archive-date=2022-03-11 |url-status=live}}</ref><ref name="mandolino2002a">{{cite journal | vauthors = Mandolino G, Ranalli P |doi=10.1300/J237v07n01_03|title=The Applications of Molecular Markers in Genetics and Breeding of Hemp |year=2002 |journal=Journal of Industrial Hemp|volume=7|pages=7–23|s2cid=84960806}}</ref><ref name="gilmore2003a">{{cite journal | vauthors = Gilmore S, Peakall R, Robertson J | title = Short tandem repeat (STR) DNA markers are hypervariable and informative in Cannabis sativa: implications for forensic investigations | journal = Forensic Science International | volume = 131 | issue = 1 | pages = 65–74 | date = January 2003 | pmid = 12505473 | doi = 10.1016/S0379-0738(02)00397-3 }}</ref><ref name="kojoka2002a">{{cite journal | vauthors = Kojoma M, Iida O, Makino Y, Sekita S, Satake M | title = DNA fingerprinting of Cannabis sativa using inter-simple sequence repeat (ISSR) amplification | journal = Planta Medica | volume = 68 | issue = 1 | pages = 60–3 | date = January 2002 | pmid = 11842329 | doi = 10.1055/s-2002-19875 | bibcode = 2002PlMed..68...60K | s2cid = 260280872 }}</ref> 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 a high degree of potential variation for selection, even in heavily selected hemp cultivars.<ref name="meijer2003a"/> 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.&nbsp;sativa'' and ''C.&nbsp;indica'' as separate species, but not ''C.&nbsp;ruderalis''. ''C.&nbsp;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.&nbsp;indica''.<ref name=hillig2004a/> In 2005, a [[Genetic testing|genetic analysis]] of the same set of accessions led to a three-species classification, recognizing ''C.&nbsp;sativa'', ''C.&nbsp;indica'', and (tentatively) ''C.&nbsp;ruderalis''.<ref name="hillig2005a"/> 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 the other putative taxa.<ref name="hillig2004b">{{cite journal|doi=10.1016/j.bse.2004.04.004|title=A chemotaxonomic analysis of terpenoid variation in Cannabis|year=2004| vauthors = Hillig KW |journal=Biochemical Systematics and Ecology|volume=32|issue=10|pages=875–891|bibcode=2004BioSE..32..875H }}</ref><!--
As of 2007, taxonomy web sites continue to list ''Cannabis'' as a genus with a single species, whilst listing Cannabis Sativa, Cannabis Indica and Cannabis Ruderalis as subspecies.<ref name="GRIN">USDA, ARS, National Genetic Resources Program. [http://www.ars-grin.gov/cgi-bin/npgs/html/splist.pl?2034 Germplasm Resources Information Network (GRIN)], National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved on 23 February 2007</ref><ref name="APNI">Barlow, Snow. 2006. [http://www.plantnames.unimelb.edu.au/Sorting/Cannabis.html Sorting ''Cannabis'' names]. Multilingual Multiscript Plant Name Database. The University of Melbourne. Retrieved on 23 February 2007</ref><ref name="ITIS">[https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=19109 Integrated Taxonomic Information System (ITIS)]. Retrieved on 23 February 2007</ref><ref name="taxonomicon">[http://www.taxonomy.nl/Taxonomicon/TaxonTree.aspx?id=6455 The Taxonomicon]. Universal Taxonomic Services. Retrieved on 23 February 2007</ref>-->

A 2020 analysis of [[single-nucleotide polymorphism]]s reports five clusters of ''cannabis'', roughly corresponding to hemps (including folk "Ruderalis") folk "Indica" and folk "Sativa".<ref>{{cite journal | vauthors = Henry P, Khatodia S, Kapoor K, Gonzales B, Middleton A, Hong K, Hilyard A, Johnson S, Allen D, Chester Z, Jin D, Rodriguez Jule JC, Wilson I, Gangola M, Broome J, Caplan D, Adhikary D, Deyholos MK, Morgan M, Hall OW, Guppy BJ, Orser C | display-authors = 6 | title = A single nucleotide polymorphism assay sheds light on the extent and distribution of genetic diversity, population structure and functional basis of key traits in cultivated north American cannabis | journal = Journal of Cannabis Research | volume = 2 | issue = 1 | pages = 26 | date = September 2020 | pmid = 33526123 | pmc = 7819309 | doi = 10.1186/s42238-020-00036-y | doi-access = free }}</ref>

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, was in fact almost 100% indica (the opposite strain).<ref>{{cite news | vauthors = Ormiston S |date=17 January 2018 |title=What's in your weed: Why cannabis strains don't all live up to their billing |url=https://www.cbc.ca/news/thenational/ormiston-pot-marijuana-cannabis-weed-genetics-1.4489974 |work=CBC |access-date=2 October 2018 |archive-date=1 October 2018 |archive-url=https://web.archive.org/web/20181001142449/https://www.cbc.ca/news/thenational/ormiston-pot-marijuana-cannabis-weed-genetics-1.4489974 |url-status=live }} (Paper is {{PMID|26308334}}.)</ref> Legalization of cannabis in Canada ({{as of|2018|October|17|lc=y|df=}}) 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, the rise of craft cannabis growers in Canada should ensure quality, experimentation/research, and diversification of strains among private-sector producers.<ref>{{cite web |url=https://licensedproducerscanada.ca/faq/will-craft-cannabis-growers-in-canada-succeed-like-craft-brewers |title=Will Craft Cannabis Growers in Canada Succeed Like Craft Brewers? |author=<!--Not stated--> |date=<!--Not stated--> |website=Licensed Producers Canada |access-date=2 October 2018 |archive-date=8 May 2019 |archive-url=https://web.archive.org/web/20190508004314/https://licensedproducerscanada.ca/faq/will-craft-cannabis-growers-in-canada-succeed-like-craft-brewers |url-status=live }}</ref>

===Popular usage===
{{hatnote|Popular terms are discerned from scientific taxonomy by the lack of italics, use of quotes and uppercasing.}}
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, [[Range (biology)|native range]], aroma, and subjective psychoactive characteristics. "Sativa" 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.<ref name="pmid30426073"/>

Mapping the morphological concepts to scientific names in the Small 1976 framework, "Sativa" generally refers to ''C.&nbsp;sativa'' subsp. ''indica'' var. ''indica'', "Indica" generally refers to ''C.&nbsp;sativa'' subsp. ''i.'' ''kafiristanica'' (also known as ''afghanica''), and "Ruderalis", being lower in THC, is the one that can fall into ''C.&nbsp;sativa'' subsp. ''sativa''. The three names fit in Schultes's framework better, if one overlooks its inconsistencies with prior work.<ref name="pmid30426073">{{cite journal | vauthors = McPartland JM | title = ''Cannabis'' Systematics at the Levels of Family, Genus, and Species | journal = Cannabis and Cannabinoid Research | volume = 3 | issue = 1 | pages = 203–212 | date = 2018 | pmid = 30426073 | pmc = 6225593 | doi = 10.1089/can.2018.0039 }}</ref> 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 [[phenotype|phenotypic]] characteristics of [[cultivar]]s 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.<ref name="pmid30426073"/>

=== Phylogeny ===
''Cannabis'' likely split from its closest relative, ''[[Humulus]]'' (hops), during 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 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.<ref>{{Cite journal| vauthors = McPartland JM, Hegman W, Long T |date=2019-05-14|title=Cannabis in Asia: its center of origin and early cultivation, based on a synthesis of subfossil pollen and archaeobotanical studies|url=http://dx.doi.org/10.1007/s00334-019-00731-8|journal=Vegetation History and Archaeobotany|volume=28|issue=6|pages=691–702|doi=10.1007/s00334-019-00731-8|bibcode=2019VegHA..28..691M |s2cid=181608199|issn=0939-6314|access-date=19 July 2021|archive-date=11 March 2022|archive-url=https://web.archive.org/web/20220311032507/https://link.springer.com/article/10.1007/s00334-019-00731-8|url-status=live}}</ref>