Black tea is more oxidized than the green, oolong and white varieties; all four varieties are made from leaves of Camellia sinensis. Black tea is generally stronger in flavor and contains more caffeine than the less oxidized teas. In Chinese black tea is known as red tea; a more accurate description of the color of the liquid. In Chinese, "black tea" is a commonly used classification for post-fermented teas, such as Pu-erh tea. However, in the western world, "red tea" more commonly refers to South African rooibos tisane.