Use the links above to see more photos.

These are cork trees (Quercus suber). They are native to SW Europe and NW Africa. Portugal accounts for about 50% of the worldwide production of cork. The actual material, the stuff you can use for making insulation and flooring, and needless to say, all those wine bottle stoppers, comes from the bark of the tree.

A cork tree is first harvested when it's about 25 years old and then every 10 or so years after that. This harvesting involves no machinery. From May through August people using only handaxes cut the bark layer as you see in the photo. It's delicate work, you don't want to cut too deeply into the tree.

Cork has been used to stopper wine since the early 1700s. But over the past few decades other types of stoppers, using other materials, like plastic and aluminium, have come along to replace it. Which is better? I'm not going to venture into that discourse.