Cork oak trunks (Quercus suber) with their bark partially stripped. The bark of this Iberian tree (known as cork) is used in a variety of products, including bottle-stoppers, panels and coverings. The bark is first stripped when the tree is 25-30 years old and then every 10 years thereafter until the tree is 150 years old. Over-cropping has led to the demise of many trees.