Both black and green tea are made from the same tea bushes. It is the manufacturing of the fresh tea leaves which differs. In black tea production the freshly plucked leaves are withered and rolled. The withering softens the tea leaves and the rolling process breaks their cell structure and allows the cell sap to ooze out and react with the natural occurring oxygen in the air. This oxidation process (sometimes also referred to as fermentation) changes not only the colour of the leaves but also their taste and natural chemical properties. Depending on the area of tea cultivation and the time of harvest black teas will vary in appearance and flavour.