Quercus suber, the cork oak. Lots of them in the woods and lanes around here, no longer harvested. Our local factory, Bouchons Trescases, buys all its cork from Portugal these days. It makes 150 million corks each year, and one of their corks is pulled somewhere in the World every 5 seconds.
I'll think of your tree when I open my bottle of wine tonight with dinner. Although, more and more are coming with screw caps.