Few plants bear the footprint of imperialism as strongly as the Asian, caffeine-containing evergreen shrub, tea. In late seventeenth-century Europe, tea was an expensive, often adulterated, luxury beverage imported from China. During the eighteenth century, it began to transform international commerce as European East India companies entered into complex trade relationships with China. However, the Chinese guarded their tea secrets well; 'foreign devils' remained largely ignorant of how tea was processed until about 150 years ago. Ignorance bred arguments especially over which species produced black and green tea; the eighteenth-century, Swedish botanist Carolus Linnaeus was convinced two species were involved.
In Britain, tea became an eighteenth-century social fad among the middle and upper classes, where a refined, often pretentious, tea-drinking culture developed. During the Industrial Revolution, the burgeoning urban population started to rely on tea and the stereotype of the British as a nation of tea drinkers was born. Governments took advantage of the tea trade and taxed it heavily; tea taxes in the American Colonies became part of the mythology of the American War of Independence. Tea was also adopted as the drug of choice by the Temperance Movement.
Governments struggled to find ways of subverting Chinese control of tea production. Linnaeus had made vain attempts to raise tea bushes in Sweden and, by the mid nineteenth century, entrepreneurs in the Americas were being urged to grow tea for the world's largest tea market - Britain. However, Britain had her own ideas about controlling the tea supply.
The British East India Company commissioned the Scottish botanist, and expert on Chinese plants, Robert Fortune to obtain living tea plants. Fortune, often travelling covertly, moved into parts of China unknown to westerners. He discovered green and black teas were produced by the same plant; the differences were in the processing. Along with 2,000 tea plants and 17,000 tea seeds Fortune shipped to India, he also included Chinese workers with proven knowledge of tea cultivation and processing. Fortune's tea plants were established in northern India, together with native Indian tea plants, and eventually spread across the British Empire as a cheap, guaranteed tea supply.
In addition to caffeine, tea contains complex mixtures of chemicals called polyphenols. The flavour of tea depends on where tea plants grow, the quality of harvested leaves and how the polyphenols are modified during processing. Consequently, processing fresh tea leaves is important for the quality of the final product.
Brockway LH 1979. Science and colonial expansion. The role of the British Royal Botanic Gardens. Yale University Press.
Fortune R 1847. Three years' wandering in the northern provinces of China, a visit to the tea, silk, and cotton countries. John Murray.
Weinberg BA and Bealer BK 2002. The world of caffeine. The science and culture of the world's most popular drug. Routledge.