THE SCIENCE OF TEA. All tea is made from the leaves of the tea plant, Camellia sinesis. Six main types of tea are produced – white, yellow, green, oolong, black and post-fermented. Each type of tea has a unique aroma, taste and visual appearance. As the six main types of tea are from the leaves of the same plant, the key to the chemical and taste differences is found in the processing – in particular, in the steps of oxidation, stopping the oxidation, forming the tea and drying it.