The plant species that is used to make tea is called the camellia sinensis. White tea, green tea, oolong tea, and black tea all come from this plant. It is an evergreen shrub that produces shiny, light green leaves that darken as they age and small white blossoms. Camellia sinensis can grow up to 30 meters in height, but cultivated shrubs are usually trimmed to waist height to make for easier harvesting. Although the camellia sinensis is native to East, South, and Southeast Asia, it is now cultivated across the world’s tropical and subtropical regions. It does well in these regions as it requires at least 50 inches of rainfall a year. However, many high quality tea plants grow at elevations up to 5,000 feet – the altitude and mountain mists help to provide the proper temperature and humidity to allow the leaves to grow more slowly, remain tender, and acquire a better taste.
Most tea plants will have a growth phase and a dormant period, which is usually during the winter. During the growing seasons, only the top one or two inches of a mature tea plant are plucked to make tea. These leaves are called flushes, and as the tea leaves are plucked, new ones will emerge. In hotter climates, plants could be picked year round as they will have several flushes. At higher elevations in cooler conditions, there will be a distinct harvesting season – leaves from the earlier flushes, usually in the springtime, will give the finest quality teas.
The quality and taste of a particular tea is influenced by both the environment (soil, climate, and altitude) and the tea maker who decided when and how the leaf is plucked and processed. For this reason, even tea fields only a small distance away from one another can yield very different tasting teas. There are more than 3,000 varieties of the tea plant, resulting in thousands of unique teas.
White tea is the least processed of all teas; the leaves of the plant are simply withered gently and dried.
Green tea undergoes slightly more processing than white teas. After the leaves are plucked, they go through a minimal amount of oxidation by being briefly steamed and then dried.
Oolong tea goes through partial oxidation that usually takes around two to three days. During this time, the leaves are rolled and sometimes slightly bruised. They are then oxidized (half the time of black tea) and then dried.
Black tea goes through a full oxidation process. This process could take anywhere from two weeks to a month. The leaves are slightly withered, rolled, and then fully oxidized before being dried.