A small tree (in cultivation, constant pruning makes it a shrub 3–4 ft or 0.9–1.2 m tall); a preparation of its leaves dried and cured by various processes; and a beverage made from these leaves. The plant, Camellia sinensis (or Thea sinensis), is an evergreen tree of the Theaceae family, native to southeastern Asia, and does best in a warm climate where the rainfall averages 90–200 in. (2200–5000 mm). The slower growth at higher altitudes improves the flavor. China, Japan, Taiwan, India, Sri Lanka, and Indonesia are among the leading tea-producing countries, with China contributing about one-half of the world's supply. According to Chinese folklore, the Chinese emperor Shen-mung discovered the use of tea about 2500 B.C. Tea leaves contain caffeine, various tannins, aromatic substances attributed to an essential oil, and other materials of a minor nature, including proteins, gums, and sugars. The tannins provide the astringency, the caffeine the stimulating properties.