All true tea, encompassing every variety from black to green to white, originates from a single plant species. The resulting beverages can look and taste dramatically different, but the variations in flavor, aroma, and color are not due to different source plants. Instead, they result from geographical cultivation and the meticulous processing the leaves undergo after plucking.
The Single Source Plant
The plant responsible for all authentic tea is Camellia sinensis, a member of the Theaceae family native to East Asia. It is cultivated across tropical and subtropical regions worldwide, though its natural habitat is the high-altitude regions of southwestern China and northern Myanmar. Growers prune the plant to a manageable height of one to two meters for easier harvesting of the young leaves and buds.
Two main varieties of Camellia sinensis dominate global production, each adapted to different climates and yielding distinct flavor profiles. The Chinese variety, Camellia sinensis var. sinensis, is a smaller-leaf cultivar that thrives in cooler, high-elevation areas and produces delicate flavors. The second variety, Camellia sinensis var. assamica, features much larger leaves and flourishes in hot, humid, low-elevation conditions, such as Assam, India. This variety produces the bolder, more robust, and astringent teas often preferred for black tea production.
How Processing Creates Different Tea Types
The vast spectrum of tea types—white, green, oolong, and black—is determined by how the freshly harvested leaves are treated. The fundamental difference lies in the degree of oxidation allowed before the leaves are dried. Oxidation is a natural chemical process where enzymes within the leaf react with oxygen, causing the leaves to brown, much like a sliced apple. The tea maker controls and either stops or encourages this reaction at a precise point.
For green tea, the goal is to prevent oxidation almost entirely to preserve the leaf’s fresh, green color and vegetal flavor compounds. This is achieved by rapidly applying heat, through steaming or pan-firing, immediately after harvest. This heat deactivates the enzymes responsible for browning, stopping the chemical change and resulting in a tea with minimal oxidation.
Conversely, black tea is created by allowing the leaves to fully oxidize, which develops the characteristic dark color and malty, rich flavor. After the leaves are withered, they are rolled or crushed to break the cell walls, initiating the oxidation process by exposing internal compounds to air. This reaction converts catechins into complex compounds that provide the tea’s reddish-brown color, strength, and depth of body.
Oolong tea occupies the middle ground, being only partially oxidized. Oxidation levels range from 10% to 80%, giving oolong a complexity that spans the flavor notes of both green and black teas.
Distinguishing True Tea from Tisanes
While many people use the term “tea” to describe any hot, brewed botanical beverage, true tea must come exclusively from Camellia sinensis. Beverages made from the infusion of other plant materials, such as herbs, spices, flowers, or fruits, are technically known as tisanes or herbal infusions.
Tisanes are defined by the absence of Camellia sinensis leaves, making them fundamentally different from true tea. Common examples include chamomile, peppermint, rooibos, and hibiscus. A significant difference is that tisanes are naturally caffeine-free, whereas all true teas contain varying levels of caffeine.