Source: Magness et al. 1971
The tea plant is an evergreen shrub or small tree that may reach 30 feet if unpruned. It is adapted to sub-tropical areas, and is widely grown for its leaves, which are dried and constitute the tea of commerce. The plants tolerate some frost, and could be grown in southern U.S., but are not because of economic factors. The leaves are lanceolate, glabrous, but sometimes pubescent on lower surface, and 2 to 5 inches long. The harvested portions are the succulent short tips and young leaves. Including older leaves reduces the quality of the tea. Leaves are harvested at intervals of 2 weeks or less. For green tea, leaves are heated quickly after harvest to inactivate enzymes. For black tea, leaves are wilted and partially dried in shallow layers, then are rolled by twisting or wringing. A short oxidation or fermentation period is followed by heating at 160 F or above to stop oxidation.