Camellia sinensis: Difference between revisions

| synonyms = * ''Camellia angustifolia'' Hung T. Chang

*{{Collapsible list |title=''Camellia arborescenssinensis'' Hung T. Chang & F. L.|{{Species Yulist

* '' |Camellia assamica'' (J. W. Masters)angustifolia |Hung T. Chang

* '' |Camellia dehungens''isarborescens |Hung T. Chang & BF. HL. ChenYu

* '' |Camellia dishiensis''assamica F|(J. CW. ZhangMasters) etHung alT. Chang

* '' |Camellia longlingensis''dehungensis F.|Hung CT. ZhangChang et& alB. H. Chen

* '' |Camellia multisepala''dishiensis Hung|F. TC. ChangZhang &et Yal. J. Tang

* '' |Camellia oleosa''longlingensis |F. C. Zhang (Loureiro)et Rehderal.

* '' |Camellia parvisepala''multisepala |Hung T. Chang & Y. J. Tang

* '' |Camellia polyneura''parvisepala |Hung T. Chang &.

* '' |Camellia waldeniae'' S. Y.thea Hu|Link

* '' |Thea cantonensis''assamica |J. W. LoureiroMasters

* '' |Thea chinensis''bohea Sims|L.

* '' |Thea cochinchinensis''cantonensis |Loureiro

* '' |Thea grandifolia''chinensis Salisbury|Sims

* '' |Thea olearia''cochinchinensis |Loureiro ex Gomes

* '' |Thea oleosa''grandifolia Loureiro|Salisbury

* '' |Thea sinensis''oleosa L.|Loureiro

* '' |Thea viridis''parvifolia L|Salisb.

'''''Camellia sinensis''''' is a [[species]] of evergreen [[shrub]] or small [[tree]] in the [[flowering plant]] family [[Theaceae]]. Its leaves and, leaf buds, areand stems can be used to produce the popular beverage [[tea]]. Common names include '''tea plant''', '''tea shrub''', and '''tea tree''' (unrelated to ''[[Melaleuca alternifolia]]'', the source of [[tea tree oil]], or the genus ''[[Leptospermum]]'' commonly called tea tree).

[[White tea]], [[yellow tea]], [[green tea]], [[oolong]], [[dark tea]] (which includes [[pu-erh tea]]) and [[black tea]] are all harvested from one of two major varieties grown today, ''C. sinensis'' var. ''sinensis'' and ''C. s.'' var. ''assamica'',<ref>[https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=506801 ITIS Standard Report Page Camellia Sinensis] {{Webarchive|url=https://web.archive.org/web/20221119190457/https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=506801 |date=19 November 2022 }} retrieved 2009-03-28.</ref> but are [[Tea processing|processed]] differently to attain varying levels of [[oxidation]] with black tea being the most oxidized and greenwhite being the least.<ref>{{cite book | last=Preedy | first=V.R. | title=Tea in Health and Disease Prevention | publisher=Elsevier Science | year=2013 | isbn=978-0-12-384937-3 | url=https://books.google.com/books?id=k3HK2WuZrsYC | access-date=February 24, 2022 | pages=199–200 | archive-date=10 November 2023 | archive-url=https://web.archive.org/web/20231110002808/https://books.google.com/books?id=k3HK2WuZrsYC | url-status=live }}</ref> [[Kukicha]] ([[twig]] tea) is also harvested from ''C. sinensis'', but uses twigs and stems rather than leaves.

[[Robert Sweet (botanist)|Robert Sweet]] shifted all formerly ''Thea'' species to the genus ''Camellia'' in 1818.<ref>{{Citation | chapter-url = http://www.bgbm.fu-berlin.de/iapt/nomenclature/code/tokyo-e/Art_13.htm | quote = The generic names ''Thea'' L. (Sp. Pl.: 515. 24 Mai 1753), and ''Camellia'' L. (Sp. Pl.: 698. 16 August 1753; Gen. Pl., ed. 5: 311. 1754), are treated as having been published simultaneously on 1 May 1753. … the combined genus bears the name ''Camellia'', since Sweet (Hort. Suburb. Lond.: 157. 1818), who was the first to unite the two genera, chose that name, and cited ''Thea'' as a synonym | author = International Association for Plant Taxonomy | author-link = International Association for Plant Taxonomy | year = 2006 | title = International Code of Botanical Nomenclature (Vienna Code) | chapter = Article 13, example 3 | edition = electronic | access-date = 5 February 2012 | archive-date = 30 November 2011 | archive-url = https://web.archive.org/web/20111130193614/http://www.bgbm.fu-berlin.de/iapt/nomenclature/code/tokyo-e/Art_13.htm | url-status = live }}.</ref> The name ''sinensis'' means "from China" in [[Latin]].

Four varieties of ''C. sinensis'' are recognized.<ref name=FOC>{{cite book | first1 = Tianlu | last1 = Min | first2 = Bruce | last2 = Bartholomew | name-list-style = vanc | chapter-url = http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200014043 | title = Flora of China | chapter = 18. Theaceae | volume = 12 | access-date = 16 October 2011 | archive-date = 29 December 2022 | archive-url = https://web.archive.org/web/20221229180605/http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200014043 | url-status = live }}</ref> Of these, ''C. sinensis'' var. ''sinensis'' and ''C. s.'' var. ''assamica'' (JW Masters) Kitamura are most commonly used for tea, and ''C. s.'' var. ''pubilimba'' Hung T. Chang and ''C. s.'' var. ''dehungensis'' (Hung T. Chang & BH Chen) TL Ming are sometimes used locally.<ref name=FOC /> The Cambodia type tea (''C. assamica'' subsp. ''lasiocaly'') was originally considered a type of assam tea. However, later genetic work showed that it is a hybrid between Chinese small leaf tea and assam type tea.<ref>Wambulwa, MC, MK Meegahakumbura, R Chalo, ''et al''. 2016. Nuclear microsatellites reveal the genetic architecture and breeding history of tea germplasm of East Africa. ''Tree Genetics & Genomes, 12.''</ref>

Assuming a generation of 12 years, Chinese small leaf tea is estimated to have diverged from Assam tea around 22,000 years ago,; while Chinese Assam tea and Indian Assam tea diverged 2,800 years ago. Thisthis divergence tea would correspond to the last [[glacial maximum]].,<ref name="Meegahakumbura 1"/><ref name="Meegahakumbura 2"/> while Chinese Assam tea and Indian Assam tea diverged 2,800 years ago.

=== Cultivars ===

Hundreds,<ref>{{Cite news|url=https://worldoftea.org/cultivar-database/|title=Tea Cultivar Database – World of Tea|work=World of Tea|access-date=2017-05-09|language=en-US|archive-date=6 June 2017|archive-url=https://web.archive.org/web/20170606164633/https://worldoftea.org/cultivar-database/|url-status=live}}</ref> if not thousands of [[cultivar]]s of ''C. sinensis'' are known. Some Japanese cultivars include:

| access-date = 1 November 2018}}</ref>

| access-date = 1 November 2018}}</ref>

''Camellia sinensis'' is mainly cultivated in tropical and subtropical climates, in areas with at least 127&nbsp;cm (50&nbsp;in) of rainfall a year. Tea plants prefer a rich and moist growing location in full to part sun, and can be grown in [[hardiness zone]]s 7–9. However, the clonal one is commercially cultivated from the equator to as far north as [[Cornwall]] and [[Scotland]] on the UK mainland.<ref>{{Citation |newspaper=Telegraph |date=17 September 2005 |url=https://www.telegraph.co.uk/gardening/main.jhtml?xml=/gardening/2005/09/17/gtea17.xml |archive-url=https://web.archive.org/web/20080105043447/https://www.telegraph.co.uk/gardening/main.jhtml?xml=%2Fgardening%2F2005%2F09%2F17%2Fgtea17.xml |archive-date=5 January 2008 |title=English tea service |access-date=19 June 2021 |url-status=dead }}.</ref><ref>{{Citation |newspaper=The Independent |date=17 November 2014 |url=https://www.independent.co.uk/life-style/food-and-drink/features/the-worlds-first-scottish-tea-at-10-a-cup-9866437.html |url-access=registration |title=The world's first Scottish tea (at £10 a cup) |access-date=25 August 2017 |archive-date=8 October 2017 |archive-url=https://web.archive.org/web/20171008130141/https://www.independent.co.uk/life-style/food-and-drink/features/the-worlds-first-scottish-tea-at-10-a-cup-9866437.html |url-status=live }}.</ref> Many high quality teas are grown at high elevations, up to {{convert|2200|m|ft|abbr=on}}, as the plants grow more slowly and acquire more flavor.

* [[Assam tea|Assam]], from the var. ''assamica'' plant, comes from the near sea-level heavily forested northeastern section of India, the state of [[Assam]]. Tea from here is rich and full-bodied. The first tea estatesestate ofin India was established in Assam in 1837. Teas are manufactured in either the ''orthodox'' process or the ''"[[crush, tear, curl]]" (CTC'') process.

Although health benefits have been assumed throughout the history of using tea as a common beverage, no high-quality evidence shows that tea confers significant benefits.<ref name="medline">{{cite web|url=https://www.nlm.nih.gov/medlineplus/druginfo/natural/997.html|title=Black tea|publisher=MedlinePlus, US National Library of Medicine|date=30 November 2017|access-date=27 February 2018|archive-date=5 July 2016|archive-url=https://web.archive.org/web/20160705113528/https://www.nlm.nih.gov/medlineplus/druginfo/natural/997.html|url-status=live}}</ref><ref name="nccih">{{cite web|title=Green tea|url=https://nccih.nih.gov/health/greentea|publisher=National Center for Complementary and Integrative Health, US National Institutes of Health|access-date=27 February 2018|date=30 November 2016|archive-date=20 March 2015|archive-url=https://web.archive.org/web/20150320021603/https://nccih.nih.gov/health/greentea|url-status=live}}</ref> In [[clinical research]] over the early 21st century, tea has been studied extensively for its potential to lower the risk of [[human diseases]], but none of this research is conclusive as of 2017.<ref name=medline/>

[[Caffeine]], a molecule produced in ''C. sinensis'', functions as a [[secondary metabolite]] and acts as a natural [[pesticide]]: it can paralyze and kill herbivorous insects feeding on the plant.<ref name="insecticide">{{cite journal | vauthors = Nathanson JA | s2cid = 42711016 | title = Caffeine and related methylxanthines: possible naturally occurring pesticides | journal = Science | volume = 226 | issue = 4671 | pages = 184–187 | date = October 1984 | pmid = 6207592 | doi = 10.1126/science.6207592 | bibcode = 1984Sci...226..184N }}</ref> Caffeine is a purine alkaloid and its biosynthesis occurs in young tea leaves and is regulated by several enzymes.<ref>{{cite journal | vauthors = Li Y, Ogita S, Keya CA, Ashihara H | title = Expression of caffeine biosynthesis genes in tea (Camellia sinensis) | journal = Zeitschrift für Naturforschung C | volume = 63 | issue = 3–4 | pages = 267–270 | date = March 2008 | pmid = 18533472 | doi=10.1515/znc-2008-3-417| doi-access = free }}</ref><ref>{{cite journal | vauthors = Kato M, Mizuno K, Fujimura T, Iwama M, Irie M, Crozier A, Ashihara H | title = Purification and characterization of caffeine synthase from tea leaves | journal = Plant Physiology | volume = 120 | issue = 2 | pages = 579–586 | date = June 1999 | pmid = 10364410 | pmc = 59297 | doi=10.1104/pp.120.2.579}}</ref> The biosynthetic pathway in ''C. sinensis'' differsis fromsimilar to other caffeine-producing plants such as [[coffee]] or [[Ilex guayusa|guayusa]].<ref>{{Cite journal |last1=Lin |first1=Zhipeng |last2=Wei |first2=Jian |last3=Hu |first3=Yongqiang |last4=Pi |first4=Dujuan |last5=Jiang |first5=Mingguo |last6=Lang |first6=Tao |date=January 2023 |title=Caffeine Synthesis and Its Mechanism and Application by Microbial Degradation, A Review |journal=Foods |language=en |volume=12 |issue=14 |pages=2721 |doi=10.3390/foods12142721 |pmid=37509813 |pmc=10380055 |issn=2304-8158 |doi-access=free }}</ref> Analysis of the pathway was carried out by harvesting young leaves and using reverse transcription [[Polymerase chain reaction|PCR]] to analyze the genes encoding the major enzymes involved in synthesizing caffeine. The gene ''TCS1'' encodes [[caffeine synthase]]. Younger leaves feature high concentrations of TCS1 transcripts, allowing more caffeine to be synthesized during this time. Dephosphorylation of xanthosine-5'-monophosphate into [[xanthosine]] is the committed step for the xanthosines entering the beginning of the most common pathway. A sequence of reactions turns [[xanthosine]] (9β-{{Small|D}}-ribofuranosylxanthine) into [[7-methylxanthosine]], then [[7-methylxanthine]], then [[theobromine]] (3,7-dimethylxanthine), and finally into caffeine (1,3,7-trimethylxanthine).

{{Commons|Camellia sinensis}}