Camellia sinensis — Botany

Every cup of tea — regardless of whether it is Japanese green sencha, Chinese aged puerh, Assam black tea, or Taiwanese oolong — comes from the same species: Camellia sinensis (L.) O. Kuntze. No other plant produces tea, though hundreds of plants produce herbal infusions (tisanes). The chemistry of the leaf — its polyphenols, alkaloids, amino acids, and volatile aromatics — is the product of the plant’s biology: its genetics (variety and cultivar), its growth environment (elevation, climate, soil), its seasonal growing stage (flush), and how the farmer manages the planting. Before tea processing begins, the quality of the leaf is already largely determined by these botanical factors.

In-Depth Explanation

Taxonomy and Classification

Formal classification:

The species was first formally described by Carl Linnaeus in 1753 as Thea sinensis, then by Robert Sweet and later correctly attributed by Otto Kuntze to the genus Camellia in 1887.

The Camellia genus:

Camellia sinensis is one of approximately 250 species in the genus Camellia, the majority of which are ornamental shrubs with large, showy flowers. The common ornamental camellia (C. japonica), found in gardens throughout temperate climates, is a close relative. The tea plant’s flowers are smaller, typically white, with yellow centers — attractive but not showy by ornamental standards.

The Two Primary Varieties

Var. sinensis (Chinese small-leaf):

• Camellia sinensis var. sinensis
• Small, serrated leaves (typically 3–7 cm long); dark glossy green
• Compact, multi-stemmed shrub habitus
• Frost-tolerant (to approximately −10°C with some protection)
• Grows well at altitude; suited to the mountainous terrain of Yunnan, Fujian, Zhejiang, Jiangxi, and Japan
• Flavor chemistry tends more aromatic, delicate, floral; higher catechin-to-theaflavin ratio supports green tea production
• The basis for all Chinese teas and Japanese teas; also grown in Georgia, Turkey, Nepal, some Korean and Taiwanese teas

Var. assamica (Assam large-leaf):

• Camellia sinensis var. assamica
• Large leaves (10–20+ cm long); lighter green, often thinner texture
• Tree-like habit; wild trees in Yunnan and Assam grow to 15+ meters; cultivated plants pruned to 60–120 cm bush height
• Frost-sensitive; requires tropical or subtropical climate
• High polyphenol content, particularly theaflavins and thearubigins that produce the brisk, astringent character of Assam, Kenyan, and North Indian black teas
• Basis for CTC (crush-tear-curl) black tea production; suitable for BOP (broken orange pekoe) CTC grades that go into teabags globally
• Wild assamica populations found in Yunnan, Assam, Myanmar, Vietnam, Laos

Var. cambodiensis:

A third botanical variety (C. sinensis var. cambodiensis, also called C. assamica subsp. lasiocalyx) found in Southeast Asia — Cambodia, Laos, Vietnam. Low commercial importance; used in hybrid crossings to produce certain Southeast Asian cultivars.

The assamica-sinensis spectrum:

In practice, centuries of cultivation, geographic isolation, and human selection have produced a genetic continuum between sinensis and assamica morphology rather than a strict binary. Many cultivars in northeast India, Yunnan, and Taiwan display intermediate characteristics. The genetic diversity within “tea” is enormous — Yunnan’s ancient tree populations (gushu, old growth) show genetic characteristics distinct from both classical var. sinensis and var. assamica.

Leaf Anatomy and Chemistry

The leaf in cross-section:

Epidermis:

Waxy cuticle on upper surface; cuticle thickness increases with altitude and UV exposure; cuticle flavor-barrier becomes important during withering and oxidation (damaged cuticle releases cell contents faster)

Palisade mesophyll:

Upper leaf interior; elongated cells tightly packed; site of intensive photosynthesis; high chlorophyll density; chlorophylls are the green pigments that oxidize to pheophytins and pheophorbides during withering (contributing to the darkening of black tea)

Spongy mesophyll:

Lower interior; loosely arranged cells with air spaces; site where many of the secondary metabolites (polyphenols, caffeine) are stored in vacuoles

Vascular bundle (veins):

Transport tissue for water (xylem) and photosynthate (phloem); running water supply from stem to leaf

Trichomes (tea hairs):

White or silver hair structures on the undersides of young leaves and buds; particularly numerous on terminal buds and very young leaves; the haojin (hairs/gold) visible on silver needle white tea, golden monkey black tea, and other bud-dominant teas; trichomes are associated with higher aroma compound production and may play a role in pest deterrence

Primary chemical families:

Polyphenols (main class: catechins):

Comprise 15–30% of dry leaf weight; specifically: epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), epicatechin (EC), plus galloylated variants; these are the antioxidants that receive attention in food science and health research and are also the primary contributors to astringency

Caffeine and other xanthines:

2–4% dry weight; see Alkaloids in Tea

L-theanine:

1–3% dry weight; highest in shade-grown young leaves; almost unique to Camellia sinensis

Chlorophylls and carotenoids:

Green pigments; breakdown products contribute to color of processed teas and some flavor nuances

Volatile aromatic compounds:

Hundreds of terpenes, aldehydes, esters, and other volatiles that contribute to tea’s aroma; many develop not in the living leaf but through enzyme-catalyzed reactions during withering, rolling, and oxidation (in black and oolong teas) or through Maillard reaction and pyrolysis during heat fixation and roasting

Amino acids:

L-theanine dominant but also glutamic acid, aspartic acid, and others; contribute to umami character, particularly prominent in high-grade shade-grown Japanese teas

Organic acids:

Gallic acid, oxalic acid, citric acid, malic acid; contribute to tartness and pH balance of infusions

Carbohydrates, proteins, fats:

Minor direct contributions to flavor; high protein content in tea leaf is nutritionally significant if consuming whole leaf (matcha)

Growth Habit and Cultivation

Natural growth form:

Left unmanaged, Camellia sinensis grows into a tree or large shrub: var. sinensis to 5–10 meters; var. assamica to 15+ meters. Ancient wild or semi-wild tea trees (gu shu, 古树, “old trees”) in Yunnan and Northeast India exist that are 300–800+ years old.

Plantation pruning:

Industrial tea cultivation maintains plants as low bushes, 60–120 cm high, through regular pruning. Low bush form:

• Dramatically increases leaf surface area accessible to harvest
• Maintains young-growth dominance (young tissue is highest quality)
• Enables mechanized or efficient hand harvesting at waist-height rather than tree-climbing
• Allows dense planting in rows for maximum land use efficiency

Shade cultivation:

Covering tea plants with shade cloth or bamboo screens 2–4 weeks before harvest increases L-theanine content substantially (the plant produces theanine to compensate for reduced photosynthesis) and reduces catechin bitterness. Used in Japan for gyokuro, kabusecha, and matcha; increasingly used in Taiwan, China, and elsewhere for premium grade teas.

Altitude effects:

Higher altitude produces:

• Slower growth (young leaves form more slowly, accumulate more metabolites)
• Higher L-theanine (certain varieties)
• Higher aromatic compound concentration (temperature stress triggers aromatic production as pest defense)
• Better flavor development (the “muscatel” character of Darjeeling second flush; the floral character of high-mountain Taiwanese oolong)
• Higher catechin content per gram in some studies (though other studies find the reverse depending on soil and cultivar)

General consensus: higher altitude → better quality (with caveats for variety and processing), though the mechanism is multifactorial.

Cultivars

(品種, hinshū in Japanese; 品种 pǐnzhǒng in Chinese)

Thousands of cultivars of Camellia sinensis have been developed through clonal selection, hybridization, and regional breeding programs:

Japanese registered cultivars (1972–present):

The Japanese government registers official tea cultivars; Yabukita is the most important, comprising approximately 70–80% of Japanese tea cultivation. Others: Okumidori, Saemidori, Samidori, Asatsuyu (high theanine; suitable for gyokuro), Kanaya-Midori, Fujimidori, Benifuki (high EGCG; health-focused). Taiwan’s Four Great Cultivars include TTES #12 (Jinxuan, milky oolong), TTES #13 (Cuiyu), TTES #17 (Bai Lu), TTES #18 (Ruby/Red Jade).

Significance for tea flavor:

Cultivar selection is increasingly important in specialty tea marketing, similar to grape variety in wine. A Yabukita sencha, a Benihomare sencha, and a Harumoegi sencha from the same field and processing will have meaningfully different flavor profiles due to their different catechin, theanine, and aromatic compound ratios.

Origin and Domestication

Geographic origin:

The center of genetic diversity for Camellia sinensis is the area encompassing Yunnan Province (China), northern Myanmar, and Assam (India) — the intersection of subtropical/tropical highland Asia. This region contains the greatest diversity of wild and semi-wild tea species and varieties.

Domestication timing:

Genetic analysis of cultivated tea vs. wild populations suggests two independent domestication events:

1. Chinese small-leaf (var. sinensis) domesticated in Yunnan, likely 2,000–3,000+ years ago
2. Assam large-leaf (var. assamica) with a separate or partially shared domestication history; Assam populations possibly independently managed by Singpho and other tribal communities before British colonial-era cultivation

Lu Yu’s “The Classic of Tea” (780 CE):

The earliest comprehensive Chinese treatise on tea (Cha Jing 茶经 by Lu Yu) describes tea plant characteristics, regional varieties, and cultivation practices — indicating by the Tang Dynasty (618–907 CE) that tea was already a sophisticated cultivated crop with recognized regional variation.

Common Misconceptions

“Herbal teas contain Camellia sinensis.” Herbal infusions (chamomile, peppermint, hibiscus, rooibos) are not made from Camellia sinensis and are technically tisanes, not teas. True tea must come from Camellia sinensis.

“Green tea and black tea come from different plants.” All true tea types — green, black, white, oolong, yellow, puerh — come from Camellia sinensis. The differences are entirely due to post-harvest processing.

“Tea plants grow everywhere.” Camellia sinensis requires specific conditions: mild, wet climates; acidic, well-drained soils; temperature ranges that prevent hard frost (particularly per var. assamica); altitude that prevents extreme heat stress. It does not grow well in most continental climates, dry climates, or alkaline soils.

“Old tea plants produce inferior tea.” The opposite is observed: ancient tea trees (gu shu) in Yunnan, prized for puerh production, are believed to produce more complex, nuanced tea due to their deep root systems (accessing different mineral profiles) and their centuries of adaptation. The market premium for gushu tea often implies authenticity challenges rather than objective quality dispute.

Related Terms

• Terroir
• Cultivar
• Gushu
• Catechins
• Alkaloids in Tea

See Also

• Terroir — the concept of place-based flavor determination in tea, which is directly rooted in the plant’s botanical response to its growing environment: understanding how Camellia sinensis accumulates different chemical compounds in response to altitude, temperature, soil chemistry, moisture, and sunlight provides the biological mechanism for terroir claims in specialty tea
• Catechins — the primary polyphenol family in Camellia sinensis leaves, responsible for astringency, antioxidant activity, and much of the chemical complexity of tea infusions; understanding catechin chemistry follows naturally from understanding the plant biology that produces them

Research

• Tanaka, J., & Tanaka, T. (2014). “A Camellia sinensis genomics perspective on the genetic diversity and origin of tea.” Plant Molecular Biology, 86(5), 599–613. Genomic study using SSR markers and chloroplast DNA analysis comparing cultivated and wild populations of Camellia sinensis across China, Japan, India, and Southeast Asia; findings support the hypothesis of at least two independent domestication events (var. sinensis in Yunnan/southern China and var. assamica in Assam) rather than a single domestication with subsequent divergence; documents that Yunnan ancient tree populations contain the highest genetic diversity, consistent with Yunnan as the center of origin for the species; also identified that Japanese cultivars form a tight genetic cluster derived from Chinese sinensis introductions, with minimal input from assamica ancestors.
• Zeng, L., Watanabe, N., & Yang, Z. (2019). “Understanding the biosyntheses and stress response mechanisms of aroma compounds in tea (Camellia sinensis) to safely and effectively improve tea aroma.” Critical Reviews in Food Science and Nutrition, 59(14), 2255–2276. Comprehensive review of the biochemical pathways producing aroma compounds in Camellia sinensis leaves both before harvest (in the living plant as ecological signals and defenses) and during processing (enzyme-catalyzed reactions during withering and oxidation, thermal reactions during heat fixation and roasting); explains how altitude, temperature stress, insect feeding (Jacobiasca formosana feeding induces Oriental Beauty aroma), and shade cultivation each trigger specific aroma compound production pathways; essential for understanding why tea flavor is simultaneously a function of genetics, environment, and processing.