Cork oak tree at the Casa do Tristo

Its trunk has gradually grown into the shape of a ball, which is probably a deformity caused by a bacterial disease, after repeated injuries caused to the tree by harvesting cork from it over the course of many years. 

It is well known that removing cork from oak trees is a rather delicate operation, because it deprives the tree of its protective outer bark. That layer lies just above the living part of the wood, which is just a few millimetres thick, and which contains the vessels that transport food and water within the tree. When the cork is removed, the oak tree protects itself by producing reddish-orange tannins. In general, it takes a tree from 7 to 9 years to generate a new layer of cork. A cork oak tree can die from having its cork harvested, so to avoid causing damage, it is a procedure that must be performed carefully by experts, using special tools. 

Fortunately for this tree, it has been about 40 years since its cork was last harvested. This is because its unusual size and shape had already turned it into a local monument.

Data for the tree (2020): 

• Height (m): 15.2 
• Girth at breast height (m): 10.85 
• Canopy diameter (m): 15.21 
• Estimated age: 250-500 years

Photographs: Xoán Fraga