Common Name: Tea Plant

General Information

Camellia sinensis is an evergreen, multi-stemmed shrub growing up to 3 metres tall (var sinensis), or a tree that can reach 10 - 15 metres tall with one main stem (var assamica). In cultivation the plants are usually kept pruned to a height of 1 - 1.5 metres and trained as a low profusely branching and spreading bush[, ].
Tea made from this species is one of the most commonly consumed drinks in the world with a history of cultivation going back 4,000 years in China. It is widely cultivated, especially in the tropical and subtropical regions of Asia. The plant also has a wide range of other uses, as a source of oil, medicines, materials etc. The plant can be grown as an ornamental, where it can be used as a hedge.

Known Hazards

None known

Botanical References

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Range

E. Asia - the exact origin is uncertain, but it is probably wild in southern China, northeast India, through Indo-China, southern Japan and Korea

Habitat

Evergreen broad-leaved forests, thickets; at elevations from 100 - 2,200 metres[]. Shaded areas[] at an elevation from 2,100 - 2,700 metres in Yunnan[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Shrub
Height	4.00 m
Growth Rate	Slow
Pollinators	Bees
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

Found from the warm temperate zone, through the subtropics and into the tropics of southern Asia, Camellia sinensis originated in an area of monsoon climates and mild winters. The plant has proved very amenable to cultivation and is now grown as far north as 42° North and south to Argentina at 27° South[]. The var sinensis can tolerate winter temperatures falling occasionally as low as -5 to -10°c, and grows best in the warm temperate to subtropical zone, whilst var assamica is less cold tolerant and is found from the subtropics to tropical areas. Depending on latitude, the plant can be grown at elevations from sea level to 2,300 metres[]. Whilst a minimum mean annual rainfall of 1,700mm is required for economic production[], the plant is reported to tolerate an annual precipitation in the range of 700 - 3,500mm[, ]. Rainfall should not fall below 50mm per month for any prolonged period[]. Generally, optimum temperatures for shoot growth are 18 - 30°c, the base temperature, below which shoot growth stops, is about 12.5°c[].
Prefers a woodland soil but thrives in a warm open well-drained loam if leafmould is added[, , ]. A calcifuge plant, preferring a pH between 5 and 7[, ]. Prefers a pH of 4.5 - 5.6[]. Prefers the partial shade of a light woodland or a woodland clearing[, ]. Tea is generally more productive when grown without shade, but shade trees may be necessary to reduce air temperatures during hot periods.
Plants develop a strong taproot and many lateral roots, giving rise to a dense mat of feeding roots in the top 50 - 75cm of the soil[]. Some lateral roots grow 3 - 4 metres deep[].
A slow-growing plant[].
Camellia sinensis is widely cultivated in tropical and warm temperate areas for its leaves which are used to make China tea[]. There are many named varieties[] and new hardier forms are being produced in China for growing in colder areas of the country[]. The Chinese form, known as 'Hsüeh-ch'a', is said to grow in areas within the snow limit on the mountains of Lingchiangfu in Yunnan province[].
The plant is also very ornamental and is sometimes grown in gardens for its aromatic flowers[],
Tea is usually distinguished by the Chinese people as small leaf tea (var sinensis) with a more northern distribution and large leaf tea (var assamica) with a more southern distribution. However, there are other varieties of Camellia sinensis and even some other species of Camellia that are used locally as tea[].
Climatic conditions have a great influence on the quality of the tea, especially on the flavour. Fast shoot growth - for instance at low altitudes, during the best part of the growing season or shortly after the bushes have been pruned back - is detrimental to the quality of tea, particularly the flavour, but induces high production[].
The distinction between green tea and black tea concerns the processing of the leaves whether they are just wilted before drying (green tea) or wilted and then fermented before drying (black tea)[].
The fragrant flowers are very attractive to insects, particularly moths[].
Plants are not very self-compatible, self-fertilized flowers produce few seeds and these are of low viability[].
Both wild and cultivated forms of tea plant (Camellia sinensis) are monoecious, insect-pollinated and self-incompatible[].

Edible Uses

The leaves are infused in hot water and used as the drink that is commonly known as tea. It is widely drunk in many areas of the world. Green tea is made from the steamed and dried leaves, whilst black tea (the form most commonly drunk in the west) is made from leaves that have been fermented and then dried[, ]. Tea contains polyphenols, these are antioxidants that help to protect the body against heart diseases, stroke and cancer[]. It also contains the stimulant caffeine which, when taken in excess, can cause sleeplessness and irritability and also, through its action as a diuretic, act to remove nutrients from the body. Tea is also rich in tannin and is a possible cause of oesophageal cancer[]. Cold tea is sometimes used as a soaking liquid to flavour dried fruit[]. One report says that the leaves are used as a boiled vegetable[]. The leaves contain about 25.7% protein, 6.5% fat, 40.8% carbohydrate, 5% ash, 3.3% caffeine, 12.9% tannin[].
Terminal sprouts with 2-3 leaves are usually hand-plucked, 10 kg of green shoots (75-80% water) produce about 2.5 kg dried tea[]. The bushes are plucked every 7-15 days, depending on the development of the tender shoots. Leaves that are slow in development always make a better flavoured product[]. Various techniques are used to produce black teas, usually during July and August when solar heat is most intense. Freshly picked leaves are spread very thinly and evenly on trays and placed in the sun until the leaves become very flaccid, requiring 13 hours or more, depending on heat and humidity. Other types of black teas are made by withering the leaves, rolling them into a ball and allowing to ferment in a damp place for 3-6 hours, at which time the ball turns a yellowish copper colour, with an agreeable fruity one[]. If this stage goes too far, the leaves become sour and unfit for tea. After fermenting, the ball is broken up and the leaves spread out on trays and dried in oven until leaves are brittle and have slight odour of tea[]. Tea is then stored in air-tight tin boxes or cans. As soon as harvested, leaves are steamed or heated to dry the natural sap and prevent oxidation to produce green tea. Still soft and pliable after the initial treatment, the leaves are then rolled and subjected to further firing. Thus dried, the leaves are sorted into various grades of green tea[].

The flowers are made into 'tempura' using the edible oil that is obtained from the seed[].

A clear golden-yellow edible oil resembling sasanqua oil is obtained from the seed[, ]. The oil needs to be refined before it is eaten.
The oblate capsule is 10 - 15mm x 15 - 30mm, 1- or 2-loculed with 1 brown, subglobose seed around 10 - 14mm in diameter per locule[].

An essential oil distilled from the fermented dried leaves is used as a commercial food flavouring[]. Tea extract is used as a flavour in alcoholic beverages, frozen dairy desserts, candy, baked goods, gelatines, and puddings[].

Tea is a potential source of food colours (black, green, orange, yellow, etc.)[].

Medicinal

Camellia sinensis is commonly used in Chinese herbalism, where it is considered to be one of the 50 fundamental herbs[]. Modern research has shown that there are many health benefits to drinking tea, including its ability to protect the drinker from certain heart diseases. It has also been shown that drinking tea can protect the teeth from decay[], because of the fluoride naturally occurring in the leaf[].
Trials have shown that tea can be effective in the clinical treatment of amoebic dysentery, bacterial dysentery, gastro-enteritis, and hepatitis. It has also been reported to have antiatherosclerotic effects and vitamin P activity[].
The leaves have a rich content of polyphenols - these are reported to have various bioactivities, such as antioxidant, antimicrobial, antitumor, and antimutagenic[].
Some caution needs to be applied when using tea in large quantities since it also contains some tannin, which is suspected of being carcinogenic[].
The plant contains caffeine and excessive use can lead to dizziness, constipation, indigestion, palpitations and insomnia[].

The leaves are antimicrobial, antioxidant, antitumor, cardiotonic, diuretic, expectorant, stimulant and astringent[, , , , , ]. They exert a decided influence over the nervous system, giving a feeling of comfort and exhilaration, but also producing an unnatural wakefulness when taken in large doses[]. They are used internally in the treatment of diarrhoea, dysentery, hepatitis and gastro-enteritis[, ].
Applied externally, the leaves are used as a poultice or wash to treat cuts, burns, bruises, insect bites, ophthalmia, swellings etc[, , ].
Only the very young leaves and leaf buds are used for medicinal purposes, these can be harvested throughout the growing season from plants over three years old and are dried for later use[].
Teabags have been poulticed onto baggy or tired eyes, compressed onto headache, or used to bathe sunburn[].

Agroforestry Uses:

The plant responds well to trimming and can be grown as a hedge[].

Other Uses

An essential oil is distilled from the fermented and dried leaves[]. It is used in perfumery and in commercial food flavouring[].

A grey dye is obtained from the pink or red petals[].
The leaves contain 13 - 18% tannin[]. The leaves also contain quercetin, a dyestuff that, when found in other plants, is much used as a dye[]. The quantity of quercetin is not given[].

Wood - moderately hard, close and even grained. It is very good for walking sticks[].

A non-drying oil is obtained from the seeds. Refined teaseed oil, made by removing the free fatty acids with caustic soda, then bleaching the oil with Fuller's earth and a sprinkling of bone black, produces an oil suitable for use in the manufacture of sanctuary or signal oil which is used for burning purposes, and in all respects is considered a favourable substitute for rapeseed, olive, or lard oils. The oil is different from cottonseed, corn, or sesame oils in that it is a non-drying oil and is not subject to oxidation changes, thus making it very suitable for use in the textile industry; it remains liquid below -18°c[].

The oil obtained from the seed of this species is likely to be very similar in quality to that obtained from Camellia oleifera. The uses of that oil are as follows:-
The seed contains 40 - 50% of a non-drying oil. The oil consists mainly of oleic acid. It is not subject to polymerize nor to oxidize, nor does it form solids at low temperatures[]. The oil has a wide range of applications. It is a good raw material for industrial uses, it is used as an illuminant, in making textiles and in the manufacture of items such as soap, margarine, hair oil, lubricants, inks and paint. It is also used in the synthesis of other high-molecular weight compounds, and to make a rustproof coating for metals. It is often used medicinally and in cosmetics in items such as skin creams and anti-wrinkle compounds[, , , , , ].
Various compounds are extracted from the seeds once the oil has been removed. These include saponins (used an emulsifying agent in pesticides, for foam-forming fire extinguishers and in detergents), tannins and pentosan[].
The seed cake has insecticidal activity, and has been proven to give effective control over a range of pests[, ].

Propagation

Seed - can be sown as soon as it is ripe in a greenhouse[]. Stored seed should be pre-soaked for 24 hours in warm water and the hard covering around the micropyle should be filed down to leave a thin covering[, , ]. It usually germinates in 1 - 3 months at 23[]. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in light shade in the greenhouse for at least their first winter. Plant them out into their permanent positions when they are more than 15cm tall and give them some protection from winter cold for their first year or three outdoors[]. Seedlings take 4 - 12 years before they start to produce seed[].
There are approximately 500 seeds per kilo[].
Cuttings of almost ripe wood, 10 - 15cm with a heel, mid summer to early autumn in a shaded frame. High percentage but slow[].
Cuttings of firm wood, 7 - 10cm with a heel, end of early summer in a frame[, ]. Keep in a cool greenhouse for the first year[].
Leaf-bud cuttings, mid summer in a frame.