Camellia sinensis

Camellia sinensis
Camellia sinensis foliage
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Ericales
Family: Theaceae
Genus: Camellia
Species:
C. sinensis
Binomial name
Camellia sinensis
Synonyms
  • Camellia thea Link
  • Thea sinensis L.

Camellia sinensis, commonly known as tea plant, tea shrub, and tea tree, is a species of evergreen shrub in the flowering plant family Theaceae. The leaves harvested from C. sinesis are brewed into tea.

Originally native to the highlands of the Hengduan–Purvanchal region between southwestern China, northern Myanmar and northeastern India, the leaves, buds and stems of C. sinensis are harvested by humans to produce tea, leading to its artificial introduction and cultivation as valuable cash crops in many other parts of the world, with China, India and Kenya being the three largest tea-producing countries.

Tea leaves used to make white tea, yellow tea, green tea, oolong, dark tea (which includes pu'er tea) and black tea (aka red tea) are all made from two of the five varieties of C. sinensis that form the bulk of the tea crops now grown, C. sinensis var. sinensis and C. sinensis var. assamica, but are processed differently to attain varying levels of oxidation, with black tea being the most oxidized and white being the least. Kukicha (twig tea) is also made from C. sinensis, but uses only twigs and stems rather than leaves and buds.

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.

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.

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. Tea trees are also variously called tea-bushes, tea-shrubs, and tea-plants.

Description

Camellia sinensis is a woody shrub or tree that is typically 1 to 5 m (3.3 to 16.4 ft) tall, but can be as tall as 20 m (66 ft). It is usually trimmed to a height of about 1 m (3.3 ft) with a flat top when in commercial tea plantations. The bark on trunks is smooth and gray with a yellow or brown tone. Young branches are yellow with a gray cast to them while new twigs are red-purple with white hairs. In older trees the trunk reaches as much as 40 cm in diameter.

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. Tea bushes reach peak productivity at ages of 30 to 50 years, but can remain productive for over a century.

C. sinensis plant, with cross-section of the flower (lower left) and seeds (lower right)

The leaves are an attractive green and tend to be smaller on cultivated plants than wild ones, ranging in size from 4 to 22 cm (1.5 to 8.5 in) and a width of 2 to 7.7 cm (0.8 to 3.0 in). 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.

Flower of tea plant
Pollen grains of C. sinensis

The flowers are white, 2.5 to 3.5 cm (1 to 1.5 in) across with six to eight petals. They bud in the leaf axils 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. They are arranged in as many as five concentric circles called whorls.

C. sinensis fruit and seeds

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. 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. They measure 1 to 2 cm and are hairless.

Taxonomy

Linnaeus did not consider this plant a Camellia but placed it in a separate genus Thea. 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.

Five varieties of Camellia sinensis are accepted:

ImageNameDescriptionDistribution
C. sinensis var. sinensisStyle fused apically 3-lobed. Widely grown for tea.China (Fujian, Guangdong, Guizhou, Guangxi, Hainan, Hunan, Hubei, Jiangxi, Jiangsu, Anhui, Sichuan, Shaanxi, Yunnan, Zhejiang), Taiwan
C. sinensis var. assamica (J.W.Masters) Kitamura Lower surface of leaves are villous along midvein. Widely grown for tea.Bhutan, China (Guangdong, Guangxi, Hainan, Yunnan), Laos, Myanmar, Nepal, Thailand, Vietnam
C. sinensis var. pubilimba Hung T. ChangSepals are white and pubescent.China (W. Guangdong, Guangxi, Hainan, SE. Yunnan)
C. sinensis var. dehungensis (Hung T. Chang & B.H.Chen) T.L.MingLower surface of leaf is appressed pubescent.China (S. Yunnan)
C. sinensis var. madoensis T. V. Nguyen, V. D. Luong & N. T. LeStyle is free half to the base.Vietnam (Phu Yen)

Camellia sinensis has 82 synonyms of the species or of four of its five varieties. This includes 45 species names.

Table of Synonyms
Name Year Rank Synonym of: Notes
Camellia angustifolia Hung T.Chang 1981 species var. pubilimba = het.
Camellia arborescens Hung T.Chang, F.L.Yu & P.S.Wang 1983 species var. sinensis = het.
Camellia assamica (Royle ex Hook.) C.D.Darl & Jan.Ammal 1945 species var. assamica ≡ hom.
Camellia assamica var. kucha Hung T.Chang, H.S.Wang & B.H.Chen 1983 variety var. assamica = het.
Camellia assamica subsp. lasiocalyx (G.Watt) W.Wight 1962 subspecies var. assamica = het.
Camellia assamica var. polyneura (Hung T.Chang, Y.J.Tan & P.S.Wang) Hung T.Chang 1998 variety var. assamica = het.
Camellia bohea (L.) Sweet 1818 species var. viridis = het.
Camellia dehungensis Hung T.Chang, H.S.Wang & B.H.Chen 1983 species var. dehungensis ≡ hom.
Camellia dehungensis Hung T.Chang & B.H.Chen 1984 species var. dehungensis = het., nom. illeg.
Camellia dishiensis F.C.Zhang, X.Y.Chen & G.B.Chen 1990 species var. pubilimba = het.
Camellia formosensis (Masam. & S.Suzuki) M.H.Su, C.F.Hsieh & C.H.Tsou 2009 species var. viridis = het.
Camellia kucha (Hung T.Chang, H.S.Wang & B.H.Chen) Hung T.Chang 2008 species var. assamica = het.
Camellia longlingensis F.C.Zhang, G.B.Chen & M.D.Tang 1990 species var. viridis = het.
Camellia manglaensis Hung T.Chang, Y.J.Tan & P.S.Wang 1983 species var. dehungensis = het.
Camellia multisepala Hung T.Chang, Y.J.Tan & P.S.Wang 1983 species var. assamica = het.
Camellia oleosa (Lour.) Rehder 1937 species var. virescens ≡ hom.
Camellia parvisepala Hung T.Chang 1981 species var. pubilimba = het.
Camellia parvisepaloides Hung T.Chang, H.S.Wang & B.H.Chen 1983 species var. dehungensis = het.
Camellia polyneura Hung T.Chang, Y.J.Tan & P.S.Wang 1983 species var. assamica = het.
Camellia scottiana Choisy 1855 species var. assamica = het., not validly publ.
Camellia sinensis var. dulcamara Q.U.Le & D.L.Nguyen 2020 variety var. assamica = het.
Camellia sinensis f. formosensis (Masam. & S.Suzuki) Kitam. 1950 form var. virescens ≡ hom.
Camellia sinensis var. kucha Hung T.Chang & S.S.Wang 1984 variety var. assamica = het.
Camellia sinensis var. lasiocalyx (G.Watt) A.P.Das & C.Ghosh 2016 variety var. assamica = het.
Camellia sinensis f. macrophylla (C.Morren) Kitam. 1950 form var. virescens = het.
Camellia sinensis f. parvifolia (Miq.) Sealy 1958 form D. viridis ≡ hom.
Camellia sinensis f. rosea (Makino) Kitam. 1950 form D. viridis ≡ hom.
Camellia sinensis f. ticinensis (Pollacci & Gallotti) Ardenghi 2020 form var. virescens = het., cited basionym not validly publ.
Camellia sinensis var. waldenae (S.Y.Hu) Hung T.Chang 1981 variety var. virescens ≡ hom.
Camellia tenuistipa Orel, Curry & Luu 2015 species var. assamica = het.
Camellia thea Link 1822 species C. sinensis ≡ hom., nom. superfl.
Camellia thea var. assamica (Royle ex Hook.) Boerl. 1901 variety var. assamica ≡ hom.
Camellia thea var. bohea (L.) G.Watt 1907 variety D. viridis ≡ hom.
Camellia thea var. lasiocalyx G.Watt 1907 variety var. assamica = het.
Camellia thea var. stricta (Hayne) G.Watt 1907 variety var. virescens = het.
Camellia thea f. ticinensis Pollacci & Gallotti 1940 form var. virescens = het., nom. nud.
Camellia thea var. viridis (L.) G.Watt 1907 variety var. virescens = het.
Camellia theifera Griff. 1854 species var. assamica = het.
Camellia theifera var. assamica (Royle ex Hook.) Greshoff 1893 variety var. assamica ≡ hom.
Camellia theifera var. macrophylla (C.Morren) Matsum. 1883 variety var. viridis = het.
Camellia viridis Sweet 1818 species D. viridis ≡ hom.
Camellia waldenae S.Y.Hu 1977 species var. viridis = het.
Thea assamica Royle ex Hook. 1847 species var. assamica ≡ hom.
Thea bohea L. 1762 species var. virescens = het.
Thea bohea var. laxa Aiton 1789 variety var. virescens = het.
Thea bohea var. stricta Aiton 1789 variety var. virescens = het.
Thea cantoniensis Lour. 1790 species var. viridis = het.
Thea chinensis Sims 1807 species var. virescens ≡ hom., orth. var.
Thea cochinchinensis Lour. 1790 species var. assamica = het.
Thea formosensis Masam. & S.Suzuki 1937 species var. virescens = het.
Thea grandifolia Salisb. 1796 species var. viridis = het.
Thea latifolia Lodd. ex Sweet 1839 species var. virescens ≡ hom.
Thea laxa Staunton 1798 species D. viridis ≡ hom.
Thea longifolia Nois. ex Steud. 1821 species var. viridis = het., not validly publ.
Thea macrophylla (C.Morren) Makino 1918 species var. viridis = het.
Thea olearia Lour. ex Gomes Mach. 1868 species var. viridis = het.
Thea oleosa Lour. 1790 species var. viridis = het.
Thea parvifolia Salisb. 1796 species var. virescens = het.
Thea sasanqua var. oleosa (Lour.) Pierre 1887 variety var. viridis = het.
Thea sinensis L. 1753 species C. sinensis ≡ hom.
Thea sinensis var. assamica (Royle ex Hook.) Pierre 1887 variety var. assamica ≡ hom., nom. illeg.
Thea sinensis var. assamica Guilf. 1883 variety var. assamica = het.
Thea sinensis var. bohea (L.) K.Koch 1853 variety var. viridis = het.
Thea sinensis var. cantoniensis (Lour.) Pierre 1887 variety var. virescens ≡ hom.
Thea sinensis var. diffusa C.Morren 1835 variety D. viridis ≡ hom.
Thea sinensis var. macrophylla C.Morren 1835 variety var. virescens = het.
Thea sinensis var. parvifolia Miq. 1867 variety var. viridis = het.
Thea sinensis var. pubescens Pierre 1887 variety var. virescens = het.
Thea sinensis var. rosea Makino 1905 variety var. viridis = het.
Thea sinensis var. rugosa C.Morren 1835 variety var. viridis = het.
Thea sinensis var. stricta C.Morren 1835 variety D. viridis ≡ hom.
Thea sinensis var. viridis Pierre 1887 variety var. virescens = het.
Thea stricta Hayne 1821 species var. viridis = het.
Thea viridis L. 1762 species var. viridis = het.
Thea viridis var. assamica (Royle ex Hook.) Choisy 1855 variety var. assamica ≡ hom.
Thea viridis var. bohea (L.) Vent. 1799 variety var. virescens = het.
Thea viridis variegata J.Dix 1861 var. viridis = het.
Thea yersinii A.Chev. ex Gagnep. 1943 species var. assamica = het., without a Latin descr.
Theaphylla anamensis Raf. 1838 species var. viridis = het.
Theaphylla cantoniensis (Lour.) Raf. 1838 species var. viridis = het.
Theaphylla laxa (Aiton) Raf. 1838 species var. viridis = het.
Theaphylla viridis (Sweet) Raf. 1838 species var. virescens ≡ hom.
Notes: ≡ homotypic synonym; = heterotypic synonym

In 2017, Chinese scientists sequenced the genome of C. s. var. assamica. It contains about three billion base pairs, which is larger than most plants previously sequenced.

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.

Tea seedling

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.

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.

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, 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.

Range and habitat

Native range of Camellia sinensis according to the borderlands theory

The origins of tea plants are obscured by their 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.

The borderlands theory suggests the species originated in the borderlands of far eastern India, north Myanmar, and southwestern China. Alternatively, other experts point to an origin to the northeast in Yunnan province within China.

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.

Cultivation

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, the species is commercially cultivated from the equator to as far north as Scotland, with the northernmost tea plantation at 59°N latitude on Shapinsay in the Orkney Islands. Many high quality teas are grown at high elevations, up to 2,200 m (7,200 ft), 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 3 m (9.8 ft). 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, but it was later identified as a variety of C. sinensis. 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.

Indian teas

Three main kinds of tea are produced in India:

Japanese teas

Tea culture in Japan from as far back as the 9th century has resulted in various types. Japanese cultivars include:

Seed-bearing fruit of C. sinensis

Products

The seeds of the tea bush (Camellia sinensis) and oil-seed camellia (Camellia oleifera) can be pressed to yield tea oil, a sweetish seasoning and cooking oil.

Tea oil should not be confused with tea tree oil, an essential oil from an unrelated species also called the tea tree (Melaleuca alternifolia). Tea tree oil is used for cosmetics and as alternative medicine, and is not fit for consumption. Tea tree oil is highly toxic when ingested, giving serious side effects that may require medical intervention, especially in children.

Pests and diseases

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

Health effects

There is no high-quality clinical evidence to indicate that drinking tea has any effect on human health. The United States Food and Drug Administration has approved a specific green tea extract ointment for treating genital warts.

Due to the presence of caffeine in tea leaves, anyone who has a sensitivity to caffeine, has been advised to avoid caffeine, or wishes to avoid the effects of caffeine should reconsider before drinking tea.

Biosynthesis of caffeine

Fresh leaves contain about 4% caffeine, as well as related compounds including theobromine. Caffeine functions as a secondary metabolite and acts as a natural pesticide: it can paralyze and kill herbivorous insects feeding on the plant. Caffeine is a purine alkaloid and its biosynthesis occurs in young tea leaves and is regulated by several enzymes. The biosynthetic pathway in C. sinensis is similar to other caffeine-producing plants such as coffee or guayusa. 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-D-ribofuranosylxanthine) into 7-methylxanthosine, then 7-methylxanthine, then theobromine (3,7-dimethylxanthine), and finally into caffeine (1,3,7-trimethylxanthine).

Biochemical pathway detailing caffeine synthesis in C. sinensis

Primary green tea catechins

See also

Notes

  1. ↑ Camellia sinensis is unrelated to Melaleuca alternifolia, the source of tea tree oil, or the genus Leptospermum, commonly called tea tree.

References

Citations

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