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
Tea production in the United States Tea production in the United States "Camellia sinensis" can be grown in warmer parts of the United States and currently the US mainland has a relatively large plantation with full mechanization in Charleston, South Carolina, and numerous small number of commercial tea gardens and smaller artisan operations that currently pick tea by hand. Many smaller sites are looking to mechanize, at least partially, within the next 5 years. Some growers feel that tea production is not viable without some mechanization, but there is evidence that unmechanized tea production is viable, albeit with lower net profit margins. Most domestically grown teas