No, all tea is made from the leaves of a single plant, Camellia sinensis. That statement excludes herbal teas, though, which are more accurately called infusions. Different categories of tea are prepared using different processes of wilting, bruising, and drying the leaves. Green tea is processed within a day or two of harvest, which preserves the natural chemicals of the fresh leaves. Black tea leaves are prepared by an oxidation process at high temperature and humidity, and then dried. Oolong tea is in between green and black: the leaves are left for a few days to wither, after which a short oxidation process is performed.