Camellia sinensis
Beyond a simple beverage, tea is a global phenomenon, and it all begins with one remarkable plant: Camellia sinensis. This unassuming evergreen shrub is the origin of every cup of white, green, oolong, and black tea we enjoy, each distinct type created through ingenious processing. Join us as we uncover the botanical marvel that has shaped cultures and economies for millennia. All true teas—from delicate white to robust black—originate from Camellia sinensis, with processing variations determining their unique characteristics. This plant boasts a rich genetic history, with distinct varieties emerging over tens of thousands of years across Asia, influencing tea's diverse flavors. Caffeine, a key component in tea, serves a crucial evolutionary purpose as a natural pesticide, protecting the plant from hungry herbivores.
AI Summary
Beyond a simple beverage, tea is a global phenomenon, and it all begins with one remarkable plant: Camellia sinensis. This unassuming evergreen shrub is the origin of every cup of white, green, oolong, and black tea we enjoy, each distinct type created through ingenious processing. Join us as we uncover the botanical marvel that has shaped cultures and economies for millennia.
- All true teas—from delicate white to robust black—originate from Camellia sinensis, with processing variations determining their unique characteristics.
- This plant boasts a rich genetic history, with distinct varieties emerging over tens of thousands of years across Asia, influencing tea's diverse flavors.
- Caffeine, a key component in tea, serves a crucial evolutionary purpose as a natural pesticide, protecting the plant from hungry herbivores.
The Global Story of Tea
Camellia sinensis is far more than just a pretty plant—it's the botanical superstar responsible for every single cup of "true tea" consumed around the world. This evergreen shrub or small tree, belonging to the Theaceae family, is the very source of white, green, oolong, and black tea.
One Plant, Many Teas
What makes a delicate white tea so different from a bold black tea, if they both come from the same plant? The secret lies in processing, specifically the degree of oxidation. Black teas are fully oxidized, giving them their dark color and robust flavor, while green teas undergo minimal oxidation, retaining their fresh, grassy notes.
Most commercially produced teas come from two main varieties of Camellia sinensis: C. sinensis var. sinensis, known for its smaller leaves, and C. sinensis var. assamica, which yields larger leaves. These two varieties are responsible for the vast majority of the world's tea production, though other varieties exist.
Tea Type Oxidation Level White Tea Least Green Tea Minimal Oolong Tea Partial Black Tea Full Dark Tea (Pu-erh) Fermented and Aged
A Botanical Portrait
Native to East Asia, the Indian Subcontinent, and Southeast Asia, Camellia sinensis is now cultivated globally in tropical and subtropical regions. Farmers typically keep the plant trimmed to about two meters, making harvesting easier, though it would grow much taller if left undisturbed. Its strong taproot anchors it firmly in the soil.
The plant produces small, yellow-white flowers, each with seven or eight delicate petals, measuring about 2.5 to 4 centimeters in diameter. But the plant's utility doesn't stop at its leaves—its seeds can be pressed to yield "tea oil," a culinary oil used for cooking and seasoning. It's important not to confuse this with "tea tree oil," which comes from a completely different plant and is used for medicinal and cosmetic purposes.
Tea leaves range from 4 to 15 centimeters long. The youngest, freshest leaves—often recognizable by their light-green color and delicate white hairs on the underside—are highly prized for tea production. These young shoots contain about 4% caffeine, along with other related compounds like theobromine.
The quality of tea is heavily influenced by the age and specific part of the leaf harvested. Generally, only the tip (or bud) and the first two to three young leaves are hand-picked. This selective plucking ensures the finest quality, and it's a labor-intensive process, repeated every one to two weeks during the growing season.
Deep Roots: History and Genetics
In 2017, Chinese scientists achieved a remarkable feat: they sequenced the entire genome of Camellia sinensis var. assamica. This massive genetic blueprint, containing about three billion base pairs, revealed a complexity greater than many other plants studied before it, offering new insights into tea's unique properties.
The plant's scientific name has a story of its own. Carl Linnaeus, the father of modern taxonomy, initially placed it in a separate genus, Thea. However, in 1818, Robert Sweet merged Thea with Camellia, honoring the Moravian Jesuit lay brother Georg Kamel, a pharmacist and missionary who studied plants in the Philippines. The species epithet, sinensis, simply means "from China" in Latin, nodding to one of its primary origins.
Tea plants are truly ancient, believed to have originated in the borderlands where northern Burma, southwestern China, and Tibet meet. While the exact wild ancestor of the small-leaf Chinese tea (C. s. var. sinensis) remains a mystery, its cultivation dates back at least 3,000 years in southeast China.
The larger-leafed C. s. var. assamica has a more complex lineage, with genetic evidence suggesting two distinct origins. One type hails from southern Yunnan, China, often hybridized with Camellia taliensis. The other, from western Yunnan, shares genetic similarities with Indian Assam tea.
Genetic studies indicate a deep evolutionary history. Chinese small-leaf tea likely diverged from Assam tea around 22,000 years ago, a split that occurred during the last glacial maximum. More recently, Chinese and Indian Assam teas diverged about 2,800 years ago, highlighting independent domestication events.
In 1836, the British introduced Chinese small-leaf tea to India. This led to fascinating hybrid varieties, such as Darjeeling tea, which is believed to be a genetic blend of Chinese small-leaf tea, native Indian Assam tea, and possibly other wild tea species.
Cultivating the Perfect Cup
Camellia sinensis thrives in tropical and subtropical climates, requiring ample rainfall—at least 127 centimeters annually. It prefers rich, moist soil and can tolerate full sun to partial shade. Surprisingly, tea is even cultivated as far north as Scotland, though high-quality teas often come from high elevations, up to 2,200 meters. At these higher altitudes, plants grow more slowly, concentrating flavors and producing more nuanced teas.
Left to its own devices, a tea plant can grow into a substantial tree. However, in cultivation, plants are meticulously pruned to a manageable waist height. This practice, known as "plucking table" formation, makes it easier for workers to harvest the precious young shoots repeatedly.
Challenges and Defenses
Even the mighty tea plant has its natural adversaries. Herbivores, such as the caterpillars of the willow beauty moth, enjoy munching on its leaves. But the plant has evolved a clever defense mechanism...
The very caffeine that gives us our morning boost is, for the tea plant, a powerful natural pesticide! Produced as a "secondary metabolite," it can paralyze and even kill insects that try to feed on its leaves, especially the tender young shoots.
The Chemistry of Your Cuppa
Caffeine is a purine alkaloid, and its creation in the tea plant is a complex biochemical dance. It primarily occurs in young leaves, regulated by specific enzymes. Scientists have mapped this biosynthetic pathway, which involves a series of methylation reactions.
Molecule Conversion Step Xanthosine Methylation 7-methylxanthosine Methylation 7-methylxanthine Methylation Theobromine Methylation Caffeine
One key player in this process is the enzyme caffeine synthase, encoded by the TCS1 gene. Young leaves, with their high concentrations of TCS1 transcripts, are like tiny caffeine factories, producing more of the compound when the plant is most vulnerable to pests. The first crucial step involves converting xanthosine-5'-monophosphate into xanthosine.
Health Benefits of Tea
For thousands of years, tea has been consumed for its perceived health benefits, and scientific research continues to explore these claims. Green tea, in particular, is widely promoted, with some studies suggesting modest positive effects for certain populations. Black tea is also lauded for its potential to improve mental alertness and possibly aid in conditions like low blood pressure, though research on some other claims, like cancer prevention, remains inconclusive.
Article
Camellia sinensis
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. Kukicha (twig tea) is also made from C. sinensis, but uses twigs and stems rather than leaves.
Names
Camellia sinensis
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
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
Camellia sinensis
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:
<table><thead><tr><th>Image</th><th>Name</th><th>Description</th><th>Distribution</th></tr></thead><tbody><tr><td></td><td>C. sinensis var. sinensis</td><td>Style fused apically 3-lobed. Widely grown for tea.</td><td>China (Fujian, Guangdong, Guizhou, Guangxi, Hainan, Hunan, Hubei, Jiangxi, Jiangsu, Anhui, Sichuan, Shaanxi, Yunnan, Zhejiang), Taiwan</td></tr><tr><td></td><td>C. sinensis var. assamica (J.W.Masters) Kitamura</td><td>Lower surface of leaves are villous along midvein. Widely grown for tea.</td><td>Bhutan, China (Guangdong, Guangxi, Hainan, Yunnan), Laos, Myanmar, Nepal, Thailand, Vietnam</td></tr><tr><td></td><td>C. sinensis var. pubilimba Hung T. Chang</td><td>Sepals are white and pubescent.</td><td>China (W. Guangdong, Guangxi, Hainan, SE. Yunnan)</td></tr><tr><td></td><td>C. sinensis var. dehungensis (Hung T. Chang & B.H.Chen) T.L.Ming</td><td>Lower surface of leaf is appressed pubescent.</td><td>China (S. Yunnan)</td></tr><tr><td></td><td>C. sinensis var. madoensis T. V. Nguyen, V. D. Luong & N. T. Le</td><td>Style is free half to the base.</td><td>Vietnam (Phu Yen)</td></tr></tbody></table>
Camellia sinensis has 82 synonyms of the species or of four of its five varieties. This includes 45 species names.
In 2017, Chinese scientists sequenced the genome of C. s. var. assamica. It contains about three billion base pairs, which was 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.
• 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]
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
Camellia sinensis
Native range of Camellia sinensis according to the borderlands theory
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. One theory is that 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
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
• 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 2,200 m (7,200 ft). 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 1,000 and 2,500 m (3,300 and 8,200 ft), Nilgiri teas are subtle and rather gentle, and are frequently blended with other, more robust teas.
Japanese teas
Tea culture in Japan from as far back as the 9th century has resulted in various types. Japanese cultivars include:
• Benifuuki • Fushun • Kanayamidori • Meiryoku • Saemidori • Okumidori • Yabukita
Seed-bearing fruit of C. sinensis
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
Tea leaves are eaten by some herbivores, such as the caterpillars of the willow beauty (Peribatodes rhomboidaria), a geometer moth.
Health effects
Camellia sinensis
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. 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.
Biosynthesis of caffeine
Camellia sinensis
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
Camellia sinensis
• (–)-Epigallocatechin • (–)-Epigallocatechin gallate • (–)-Epicatechin gallate • (–)-Epicatechin