Camellia sinensis is a species of evergreen shrub or small tree in the flowering plant family Theaceae.

[5] The young, light-green leaves are preferably harvested for tea production when they have short, white hairs on the underside.

Georg Kamel,[8] SJ (1661–1706), a Moravian-born Jesuit lay brother, pharmacist, and missionary to the Philippines.

Carl Linnaeus chose his name in 1753 for the genus to honor Kamel's contributions to botany[9] (although Kamel did not discover or name this plant, or any Camellia,[10] and Linnaeus did not consider this plant a Camellia but a Thea).

[13] Tea plants are native to East Asia, and probably originated in the borderlands of north Burma and southwestern China.

[15][16] Given their genetic differences forming distinct clades, Chinese Assam type tea (C. s. var.

Many types of Southern Yunnan Assam tea have been hybridized with the closely related species Camellia taliensis.

Some Japanese cultivars include: 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 clonal one is commercially cultivated from the equator to as far north as Cornwall and Scotland on the UK mainland.

The Chinese plant is a small-leafed bush with multiple stems that reaches a height of some 3 m (9.8 ft).

[25] Caffeine, a molecule produced in C. sinensis, functions as a secondary metabolite and acts as a natural pesticide: it can paralyze and kill herbivorous insects feeding on the plant.

[27] Caffeine is a purine alkaloid and its biosynthesis occurs in young tea leaves and is regulated by several enzymes.

[30] 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.

Younger leaves feature high concentrations of TCS1 transcripts, allowing more caffeine to be synthesized during this time.