The Cork Oak of the Palco

This is the one tree on the walk you can put a hand on and be surprised. Cork oak grows an outer bark up to thirty centimetres thick, spongy and slightly warm to the touch, and it is the only European tree whose bark regenerates completely after being stripped, which is why Portugal and Spain harvest it on a nine-year cycle for wine corks and floor tiles. Four metres twenty around the trunk and twenty-eight metres tall, this one has never been harvested. A stripped cork oak carries a smooth ochre trunk for years afterwards, so the deep fissured layer here is the mark of a tree left alone since it was planted. The register adds something worth knowing: several smaller cork oaks stand scattered around it in no pattern at all, which is what happens when an old tree in an irrigated garden is left long enough to seed itself. The bark is also why the species survives fire across the Iberian dehesa. It insulates the trunk well enough that the tree comes back from a burn that kills everything around it, a useful thing to have evolved in a landscape people have been burning for grazing for four thousand years. In a garden of imported curiosities, this one is a Mediterranean native doing what it does at home.