Decaffeination this trait could be bred into other coffee plants by crossing them with "C. charrieriana", or an equivalent effect could be achieved by knocking out the gene for caffeine synthase in normal coffee plants. Tea may also be decaffeinated, usually by using processes analogous to the direct method or the CO process, as described above. The process of oxidizing tea leaves to create black tea ("red" in Chinese tea culture) or oolong tea leaves from green leaves does not affect the amount of caffeine in the tea, though tea-plant subspecies (i.e., "Camellia sinensis sinensis" vs. "Camellia sinensis assamica") may differ
History of tea "Camellia sinensis"—the area including the northern part of Burma, and Yunnan and Sichuan provinces of China. Yunnan Province has also been identified as "the birthplace of tea...the first area where humans figured out that eating tea leaves or brewing a cup could be pleasant." Fengqing County in the Lincang City Prefecture of Yunnan Province in China is said to be home to the world's oldest cultivated tea tree, some 3,200 years old. According to "The Story of Tea", tea drinking likely began in Yunnan province during the Shang Dynasty (1500 BC–1046 BC), as a medicinal drink. From there, the drink