Cork oaks are generous trees. They provide homes to the birds that nest on their branches and nourishment to the black pigs that feed on their acorns. The bark of the oak tree is manually stripped to produce cork, a natural material known since ancient times for its versatility. Pliny the Elder writes in his Natural History that the bark can be used to make anchors, drag-ropes, and shoe soles. The bows and keels of the ships used by Portuguese navigators were made of cork.

After each stripping, the oak bark grows back. The first stripping generally occurs when the tree is 25-year old. Subsequent strippings follow a nine-year cycle. Trees are marked with a number that indicates the time of the last stripping. It takes 43 years for the bark to be thick enough to produce wine corks. So, most wine corks come from oaks that are much older than the wine they protect.

Cork oaks live for roughly two centuries. Their roots make them resilient to winds and droughts so they can grace the landscape of Portugal with their generosity and beauty.