Camellia sinensis

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Camellia sinensis is a species of evergreen shrub or small tree in the flowering plant family Theaceae. Its leaves, leaf buds, and stems are used to produce 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 made from two of the five varieties which form the main crops now grown, C. sinensis var. sinensis and C. s. var. assamica, but are processed differently to attain varying levels of oxidation with black tea being the most oxidized and white being the least.Template:Sfn Kukicha (twig tea) is also made from C. sinensis, but uses twigs and stems rather than leaves.

Names

The name sinensis is a compound meaning "from China" in Botanical Latin. The two parts are sin from Latin meaning China and ensis the suffix meaning place of origin.Template:Sfn

The generic name Camellia is taken from the Latinized name of Rev. Georg Kamel, SJ (1661–1706), a Moravian-born Jesuit lay brother, pharmacist, and missionary to the Philippines.Template:Sfn

Camellia sinensis is widely known by the common name tea tree, a name in use since 1760. However, it is also used to refer to shrubs or trees of the myrtle family from Australia and New Zealand, most frequently species in Leptospermum or Melaleuca the first usage dating to 1790.Template:Sfn Tea trees are also variously called tea-bushes, tea-shrubs, and tea-plants.Template:Sfn Template:Sfn

Description

Camellia sinensis is a woody shrub or tree that is typically Template:Cvt tall,Template:Sfn but can be as tall as Template:Cvt.Template:Sfn It is usually trimmed to a height of about Template:Cvt with a flat top when in commercial tea plantations.Template:Sfn The bark on trunks is smooth and gray with a yellow or brown tone.Template:Sfn Young branches are yellow with a gray cast to them while new twigs are red-purple with white hairs.Template:Sfn In older trees the trunk reaches as much as 40 cm in diameter.Template:Sfn

In seedlings the taproot is dominant, but in mature plants the distribution of roots depends upon individual plant characteristics and growing conditions. In areas with shallow soils or high water tables tea bushes will have a shallow, fibrous root system while in areas with deep soils root have been found at depths of 5.5 m.Template:Sfn Tea bushes reach peak productivity at ages of 30 to 50 years, but can remain productive for over a century.Template:Sfn

The leaves are an attractive green and tend to be smaller on cultivated plants than wild ones, ranging in size from Template:Cvt and a width of Template:Cvt.Template:Sfn Their shape is elliptic, oblong-elliptic, or oblong, and they have a leathery texture. The upper surface is shining dark green and hairless while the underside is pale green and can be hairless or pubescent, covered in plant hairs. The center vein is raised above the surface of the leaf on both sides as are the smaller seven to nine veins to each side. The netlike veins between are also visible. The leaf tip has a wide angle and the edges are serrate to serrulate, having asymmetrical teeth that point forwards to very fine serrations.Template:Sfn

The flowers are white, Template:Cvt across with six to eight petals. They bud in the leaf Template:Plantgloss and can be solitary or have up to three in a cluster. On the back of the flower there will be five sepals 3–5 mm long. One to three of the petals will be somewhat sepal-like and hidden behind the five visible at the front of the flower. The center of the flower is filled with numerous hairless stamens 8–13 mm long.Template:Sfn They are arranged in as many as five concentric circles called whorls.Template:Sfn

The fruit is a capsule with globe shape, usually flattened at the ends and measuring 1–1.5 cm top to bottom and 1.5-3.5 cm in diameter.Template:Sfn Template:Sfn Each fruit will have one to three round chambers with one or two seeds in each. The seeds are brown to almost black in color and are round, half-spheres, or have mulpile flat faces.Template:Sfn They measure 1 to 2 cm and are hairless.Template:Sfn Template:Sfn

Taxonomy

Linnaeus did not consider this plant a Camellia but placed it in a separate genus Thea.<ref>Template:Citation</ref> Then in 1818, Robert Sweet merged the two genera, selecting Camellia for the merged genus, and shifted all the former Thea species to that genus.<ref>Template:Citation.</ref>

Five varieties of Camellia sinensis are accepted:Template:Sfn

Name	Description	Distribution
C. sinensis var. sinensisTemplate:Sfn	Style fused apically 3-lobed. Widely grown for tea.	China (Fujian, Guangdong, Guizhou, Guangxi, Hainan, Hunan, Hubei, Jiangxi, Jiangsu, Anhui, Sichuan, Shaanxi, Yunnan, Zhejiang), TaiwanTemplate:Sfn
C. sinensis var. assamica Template:Au Template:Sfn	Lower surface of leaves are villous along midvein. Widely grown for tea.	Bhutan, China (Guangdong, Guangxi, Hainan, Yunnan), Laos, Myanmar, Nepal, Thailand, VietnamTemplate:Sfn
C. sinensis var. pubilimba Template:Au Template:Sfn	Sepals are white and pubescent.	China (W. Guangdong, Guangxi, Hainan, SE. Yunnan)Template:Sfn
C. sinensis var. dehungensis Template:Au Template:Sfn	Lower surface of leaf is appressed pubescent.	China (S. Yunnan)Template:Sfn
C. sinensis var. madoensis Template:Au Template:Sfn	Style is free half to the base.	Vietnam (Phu Yen)Template:Sfn

Camellia sinensis has Template:Table row counter synonyms of the species or of four of its five varieties. This includes 45 species names.Template:Sfn Template:Sfn Template:Sfn Template:Sfn Template:Sfn

Table of Synonyms
Name	Year	Rank	Synonym of:	Notes
Camellia angustifolia Template:Small	1981	species	var. pubilimba	= het.
Camellia arborescens Template:Small	1983	species	var. sinensis	= het.
Camellia assamica Template:Small	1945	species	var. assamica	≡ hom.
Camellia assamica var. kucha Template:Small	1983	variety	var. assamica	= het.
Camellia assamica subsp. lasiocalyx Template:Small	1962	subspecies	var. assamica	= het.
Camellia assamica var. polyneura Template:Small	1998	variety	var. assamica	= het.
Camellia bohea Template:Small	1818	species	var. viridis	= het.
Camellia dehungensis Template:Small	1983	species	var. dehungensis	≡ hom.
Camellia dehungensis Template:Small	1984	species	var. dehungensis	= het., nom. illeg.
Camellia dishiensis Template:Small	1990	species	var. pubilimba	= het.
Camellia formosensis Template:Small	2009	species	var. viridis	= het.
Camellia kucha Template:Small	2008	species	var. assamica	= het.
Camellia longlingensis Template:Small	1990	species	var. viridis	= het.
Camellia manglaensis Template:Small	1983	species	var. dehungensis	= het.
Camellia multisepala Template:Small	1983	species	var. assamica	= het.
Camellia oleosa Template:Small	1937	species	var. virescens	≡ hom.
Camellia parvisepala Template:Small	1981	species	var. pubilimba	= het.
Camellia parvisepaloides Template:Small	1983	species	var. dehungensis	= het.
Camellia polyneura Template:Small	1983	species	var. assamica	= het.
Camellia scottiana Template:Small	1855	species	var. assamica	= het., not validly publ.
Camellia sinensis var. dulcamara Template:Small	2020	variety	var. assamica	= het.
Camellia sinensis f. formosensis Template:Small	1950	form	var. virescens	≡ hom.
Camellia sinensis var. kucha Template:Small	1984	variety	var. assamica	= het.
Camellia sinensis var. lasiocalyx Template:Small	2016	variety	var. assamica	= het.
Camellia sinensis f. macrophylla Template:Small	1950	form	var. virescens	= het.
Camellia sinensis f. parvifolia Template:Small	1958	form	D. viridis	≡ hom.
Camellia sinensis f. rosea Template:Small	1950	form	D. viridis	≡ hom.
Camellia sinensis f. ticinensis Template:Small	2020	form	var. virescens	= het., cited basionym not validly publ.
Camellia sinensis var. waldenae Template:Small	1981	variety	var. virescens	≡ hom.
Camellia tenuistipa Template:Small	2015	species	var. assamica	= het.
Camellia thea Template:Small	1822	species	C. sinensis	≡ hom., nom. superfl.
Camellia thea var. assamica Template:Small	1901	variety	var. assamica	≡ hom.
Camellia thea var. bohea Template:Small	1907	variety	D. viridis	≡ hom.
Camellia thea var. lasiocalyx Template:Small	1907	variety	var. assamica	= het.
Camellia thea var. stricta Template:Small	1907	variety	var. virescens	= het.
Camellia thea f. ticinensis Template:Small	1940	form	var. virescens	= het., nom. nud.
Camellia thea var. viridis Template:Small	1907	variety	var. virescens	= het.
Camellia theifera Template:Small	1854	species	var. assamica	= het.
Camellia theifera var. assamica Template:Small	1893	variety	var. assamica	≡ hom.
Camellia theifera var. macrophylla Template:Small	1883	variety	var. viridis	= het.
Camellia viridis Template:Small	1818	species	D. viridis	≡ hom.
Camellia waldenae Template:Small	1977	species	var. viridis	= het.
Thea assamica Template:Small	1847	species	var. assamica	≡ hom.
Thea bohea Template:Small	1762	species	var. virescens	= het.
Thea bohea var. laxa Template:Small	1789	variety	var. virescens	= het.
Thea bohea var. stricta Template:Small	1789	variety	var. virescens	= het.
Thea cantoniensis Template:Small	1790	species	var. viridis	= het.
Thea chinensis Template:Small	1807	species	var. virescens	≡ hom., orth. var.
Thea cochinchinensis Template:Small	1790	species	var. assamica	= het.
Thea formosensis Template:Small	1937	species	var. virescens	= het.
Thea grandifolia Template:Small	1796	species	var. viridis	= het.
Thea latifolia Template:Small	1839	species	var. virescens	≡ hom.
Thea laxa Template:Small	1798	species	D. viridis	≡ hom.
Thea longifolia Template:Small	1821	species	var. viridis	= het., not validly publ.
Thea macrophylla Template:Small	1918	species	var. viridis	= het.
Thea olearia Template:Small	1868	species	var. viridis	= het.
Thea oleosa Template:Small	1790	species	var. viridis	= het.
Thea parvifolia Template:Small	1796	species	var. virescens	= het.
Thea sasanqua var. oleosa Template:Small	1887	variety	var. viridis	= het.
Thea sinensis Template:Small	1753	species	C. sinensis	≡ hom.
Thea sinensis var. assamica Template:Small	1887	variety	var. assamica	≡ hom., nom. illeg.
Thea sinensis var. assamica Template:Small	1883	variety	var. assamica	= het.
Thea sinensis var. bohea Template:Small	1853	variety	var. viridis	= het.
Thea sinensis var. cantoniensis Template:Small	1887	variety	var. virescens	≡ hom.
Thea sinensis var. diffusa Template:Small	1835	variety	D. viridis	≡ hom.
Thea sinensis var. macrophylla Template:Small	1835	variety	var. virescens	= het.
Thea sinensis var. parvifolia Template:Small	1867	variety	var. viridis	= het.
Thea sinensis var. pubescens Template:Small	1887	variety	var. virescens	= het.
Thea sinensis var. rosea Template:Small	1905	variety	var. viridis	= het.
Thea sinensis var. rugosa Template:Small	1835	variety	var. viridis	= het.
Thea sinensis var. stricta Template:Small	1835	variety	D. viridis	≡ hom.
Thea sinensis var. viridis Template:Small	1887	variety	var. virescens	= het.
Thea stricta Template:Small	1821	species	var. viridis	= het.
Thea viridis Template:Small	1762	species	var. viridis	= het.
Thea viridis var. assamica Template:Small	1855	variety	var. assamica	≡ hom.
Thea viridis var. bohea Template:Small	1799	variety	var. virescens	= het.
Thea viridis variegata Template:Small	1861		var. viridis	= het.
Thea yersinii Template:Small	1943	species	var. assamica	= het., without a Latin descr.
Theaphylla anamensis Template:Small	1838	species	var. viridis	= het.
Theaphylla cantoniensis Template:Small	1838	species	var. viridis	= het.
Theaphylla laxa Template:Small	1838	species	var. viridis	= het.
Theaphylla viridis Template:Small	1838	species	var. virescens	≡ hom.
Notes: ≡ homotypic synonym; = heterotypic synonym

In 2017, Chinese scientists sequenced the genome of C. s. var. assamica.<ref>Template:Cite journal</ref> It contains about three billion base pairs, which was larger than most plants previously sequenced.<ref>Template:Cite news</ref>

The Cambodia type tea ("C. assamica subsp. lasiocalyx") 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 tea.<ref>Template:Cite journal</ref>

Chinese (small leaf) tea [C. sinensis var. sinensis]
Chinese Western Yunnan Assam (large leaf) tea [C. sinensis var. assamica]
Indian Assam (large leaf) tea [C. sinensis var. assamica]
Chinese Southern Yunnan Assam (large leaf) tea [C. sinensis var. assamica]

Chinese (small leaf) tea may have originated in southern China possibly with hybridization of unknown wild tea relatives. However, since no wild populations of this tea are known, the precise location of its origin is speculative.<ref name="Meegahakumbura-2016"/><ref name="Meegahakumbura-2018"/>

Given their genetic differences forming distinct clades, Chinese Assam type tea (C. s. var. assamica) may have two different parentages – one being found in southern Yunnan (Xishuangbanna, Pu'er City) and the other in western Yunnan (Lincang, Baoshan). Many types of Southern Yunnan Assam tea have been hybridized with the closely related species Camellia taliensis. Unlike Southern Yunnan Assam tea, Western Yunnan Assam tea shares many genetic similarities with Indian Assam type tea (also C. s. var. assamica). Thus, Western Yunnan Assam tea and Indian Assam tea both may have originated from the same parent plant in the area where southwestern China, Indo-Burma, and Tibet meet. However, as the Indian Assam tea shares no haplotypes with Western Yunnan Assam tea, Indian Assam tea is likely to have originated from an independent domestication. Some Indian Assam tea appears to have hybridized with the species Camellia pubicosta.<ref name="Meegahakumbura-2016">Template:Cite journal</ref><ref name="Meegahakumbura-2018">Template:Cite journal</ref>

Assuming a generation of 12 years, Chinese small leaf tea is estimated to have diverged from Assam tea around 22,000 years ago; this divergence would correspond to the last glacial maximum,<ref name="Meegahakumbura-2016"/><ref name="Meegahakumbura-2018"/> while Chinese Assam tea and Indian Assam tea diverged 2,800 years ago.

Chinese small leaf type tea was introduced into India in 1836 by the British and some Indian Assam type tea (e.g. Darjeeling tea) appear to be genetic hybrids of Chinese small leaf type tea, native Indian Assam, and possibly also closely related wild tea species.<ref>Template:Cite journal</ref>

Range and habitat

The origins of tea plants is obscured by its long history of cultivation. The natural range is unknown, though it is reasonably certain that the species comes from East Asia with the exact location being debated by experts.Template:Sfn One theory is that the species originated in the borderlands of far eastern India, north Myanmar, and southwestern China.Template:Sfn Alternatively, other experts point to an origin to the northeast in Yunnan province within China.Template:Sfn In the Plants of the World Online database many more places are listed as part of the native range including not only southcentral and southwest China, Assam and the eastern Himalayas in India, and Myanmar, but also Laos, Thailand, and Vietnam.Template:Sfn

Cultivation

Template:Main

Camellia sinensis is mainly cultivated in tropical and subtropical climates, in areas with at least 127 cm (50 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 zones 7–9. However, species is commercially cultivated from the equator to as far north as Scotland,<ref name="TeaScot">Template:Cite web</ref> with the northernmost tea plantation at 59°N latitude on Shapinsay in the Orkney Islands.<ref>Template:Cite web</ref> Many high quality teas are grown at high elevations, up to Template:Convert, as the plants grow more slowly and acquire more flavour.

Tea plants will grow into a tree if left undisturbed, but cultivated plants are pruned to waist height for ease of plucking. Two principal varieties are used, the small-leaved Chinese variety plant (C. s. var. sinensis) and the large-leaved Assamese plant (C. s. var. assamica), used mainly for black tea. Tea trees can remain productive for many years.

Chinese teas

The Chinese plant is a small-leafed bush with multiple stems that reaches a height of some Template:Convert. It is native to southeast China. The first tea plant variety to be discovered, recorded, and used to produce tea dates back 3,000 years ago; it yields some of the most popular teas.

C. s. var. waldenae was considered a different species, C. waldenae by SY Hu,<ref name="ICS">Template:Citation</ref> but it was later identified as a variety of C. sinensis.<ref>Template:Cite journal.</ref> This variety is commonly called Waldenae Camellia; it is grown on Sunset Peak and Tai Mo Shan in Hong Kong, and also occurs in Guangxi province.<ref name="ICS" />

Indian teas

Three main kinds of tea are produced in India:

Assam, from C. s. var. assamica, 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 estate in India was established in Assam in 1837. Teas are manufactured in either the orthodox process or the "crush, tear, curl" (CTC) process.
Darjeeling, from C. s. var. sinensis, is from the cool and wet Darjeeling highland region, tucked in the foothills of the Himalayas. Tea plantations could be at altitudes as high as Template:Convert. The tea is delicately flavoured, and considered to be one of the finest teas in the world. The Darjeeling plantations have three distinct harvests, termed 'flushes', and the tea produced from each flush has a unique flavour. First (spring) flush teas are light and aromatic, while the second (summer) flush produces tea with a bit more bite. The third, or autumn flush gives a tea that is lesser in quality.
Nilgiri is from a southern region of India almost as high as Darjeeling. Grown at elevations between Template:Convert, Nilgiri teas are subtle and rather gentle, and are frequently blended with other, more robust teas.Template:Citation needed

Japanese teas

Tea culture in Japan from as far back as the 9th century<ref>Template:Cite book</ref> has resulted in various types. Japanese cultivars include:

Benifuuki<ref name="FAO-1">Template:Cite web</ref>
Fushun<ref name="FAO-2">Template:Cite web</ref>
Kanayamidori<ref name="FAO-1" />
Meiryoku<ref name="FAO-2" />
Saemidori<ref name="FAO-2" />
Okumidori<ref name="FAO-2" />
Yabukita<ref name="FAO-2" />

Products

The seeds of the tea bush and oil-seed camellia (Camellia oleifera) can be pressed to yield tea oil, a sweetish seasoning and cooking oil that should not be confused with tea tree oil, an essential oil that is used for medical and cosmetic purposes, and originates from the leaves of a different plant.

Pests and diseases

Template:Main Tea leaves are eaten by some herbivores, such as the caterpillars of the willow beauty (Peribatodes rhomboidaria), a geometer moth.

Health effects

Template:Main Green tea has been consumed for health purposes for thousands of years and is currently promoted for various health benefits though scientific studies show mixed results, with some evidence suggesting modest effects in certain populations; the United States Food and Drug Administration has approved a specific green tea extract ointment for treating genital warts.<ref name="nccih">Template:Cite web</ref> Black tea is rated by the Natural Medicines Comprehensive Database of Natural Standard as likely effective for improving mental alertness, possibly effective for conditions like low blood pressure, heart attack risk, osteoporosis, ovarian cancer, and Parkinson's disease, possibly ineffective for various cancers and diabetes, and lacks sufficient evidence for other uses.<ref>Template:Cite web</ref>

Biosynthesis of caffeine

Fresh leaves contain about 4% caffeine, as well as related compounds including theobromine.<ref>Template:Cite web</ref> Caffeine functions as a secondary metabolite and acts as a natural pesticide: it can paralyze and kill herbivorous insects feeding on the plant.<ref name="Nathanson-1984">Template:Cite journal</ref> Caffeine is a purine alkaloid and its biosynthesis occurs in young tea leaves and is regulated by several enzymes.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> The biosynthetic pathway in C. sinensis is similar to other caffeine-producing plants such as coffee or guayusa.<ref>Template:Cite journal</ref> Analysis of the pathway was carried out by harvesting young leaves and using reverse transcription 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-Template:Small-ribofuranosylxanthine) into 7-methylxanthosine, then 7-methylxanthine, then theobromine (3,7-dimethylxanthine), and finally into caffeine (1,3,7-trimethylxanthine).