Tea, the world’s second most consumed beverage after water, originates from the leaves of an evergreen shrub or small tree. This plant is scientifically known as Camellia sinensis. All true teas, including Black, Green, Oolong, and White, are derived exclusively from this single plant species. The cultivation of this plant began in East Asia, including China, northern Myanmar, and the Assam area of India.
The Source: Defining the Camellia sinensis Plant
The Camellia sinensis plant is an evergreen that can grow into a tree reaching heights of up to 50 feet if left untended. For commercial tea production, however, growers consistently prune the plants into low-lying bushes, typically kept at three to five feet to facilitate harvesting. The leaves are a dark, glossy green with a leathery texture and finely serrated edges. They are the source of all non-herbal tea.
Two primary varieties of the plant account for nearly all commercial tea production. Camellia sinensis var. sinensis, often called the China bush, is characterized by smaller leaves and a greater tolerance for cooler temperatures, making it hardy enough for high-altitude cultivation. This variety is often associated with the delicate, nuanced flavor profiles found in many Chinese green and white teas.
Camellia sinensis var. assamica, known as the Assam bush, thrives in warmer, more humid, and often lowland environments. It produces larger leaves and can naturally grow into a taller tree than the China bush. The assamica variety yields the bolder, more robust, and often malty flavors commonly associated with traditional black teas.
The Essential Environment for Tea Cultivation
Tea cultivation requires environmental conditions that mimic the plant’s native subtropical and tropical habitats. The plant thrives in warm climates, ideally with growing season temperatures between 70°F and 85°F. High humidity is also beneficial, with optimal growth occurring when relative humidity is between 75% and 85%.
Rainfall is necessary, with most growing regions receiving at least 50 inches annually. Although the plant requires consistent moisture, the soil must be well-drained to prevent waterlogging, which can damage the roots. Tea is a calcifuge, requiring highly acidic soil with an optimal pH range of 4.5 to 5.5.
Tea is often cultivated on hillsides and mountain slopes at higher altitudes. Growing tea at elevated heights encourages slower growth, which concentrates the chemical compounds that contribute to flavor and aroma. Major growing regions, such as India, China, Sri Lanka, and Kenya, meet these requirements of warm, wet conditions and acidic soil.
Harvesting and the Origin of Tea Varieties
Harvested tea quality is determined by “plucking,” which is highly labor-intensive and traditionally done by hand. Tea pickers focus on gathering the newest growth, known as the “flush,” which consists of the terminal bud and the two youngest leaves directly beneath it. This young growth contains the highest concentration of desirable flavor compounds.
The difference in the final product is entirely due to the processing methods applied after plucking. All varieties of tea originate from the same Camellia sinensis leaf. The primary factor differentiating the types is the degree of enzymatic oxidation the leaves are allowed to undergo.
Oxidation begins when the leaf structure is broken during handling or rolling, exposing the internal enzymes to oxygen. To make Green tea, this process is quickly halted, usually by steaming or pan-firing the leaves shortly after harvest, resulting in little to no oxidation. Black tea, in contrast, is allowed to fully oxidize, which darkens the leaves and creates its characteristic strong flavor. Oolong tea is considered a partially oxidized tea, arrested between the stages for green and black tea, creating a complex spectrum of flavors and colors.