Tea is a beverage made from the processed leaves, buds or stems of the plant whose scientific name is Camellia sinensis. Processing includes some or all of the following steps: plucking; withering; rolling; oxidizing; heating; and packaging. Sometimes herbs, flowers, spices, fruits, or flavorings are added.

The four basic types of tea (in order from most to least processed): are black, oolong, green and white teas. The term 'herbal tea' usually refers to infusions or decoctions of fruit or herbs, e.g., rosehip, chamomile, hibiscus, dried apple, other than Camellia sinensis. Tea purists avoid the word 'tea' in these cases and call the beverage a tisane.

Tea is a natural source of the amino acid theanine; methylxanthines such as caffeine and theobromine; and catechins (polyphenolic antioxidants). The beverage contains almost no carbohydrates, fat or protein and has a cooling, slightly bitter and astringent flavor.

"In loose, deep, acid soil, at high altitude, where summer and autumn rains feed well-drained ground, in the heat, with little wind, where morning fog wraps the mountains, and other plants die, Camellia sinensis flourishes in a setting of natural splendor." (The Little Book of Tea; Kitti Cha Sangmanee; Catherine Donzel; Stephane Melchior-Durand; Alain Stella)

Cultivation

Camellia sinensis can thrive at elevations of up to 5,000 feet (1500 meters). At these higher elevations, the plants mature more slowly and tend to develop unique and highly desirable flavors. A mature tea tree can reach sixty feet in height, making leaf gathering difficult at best. Under cultivation, the plants are kept to a more manageable size so that the tea gatherers - usually women - can pluck leaves efficiently. In orthodox tea manufacture, relatively strict guidelines define how much of the plant is picked, i.e., only buds; two leaves and a bud; three leaves and a bud; etc. Various criteria are used for various styles of tea.

New buds and leaves are called flushes; a plant can grow a new flush every seven to ten days during the growing season. The two principal varieties of tea plant are the small-leaved China plant, Camellia sinensis sinensis, and the large-leaved Assam plant, Camellia sinensis assamica.