This young oak tree is taking advantage of all the nutrients available from a rotting tree stump and is actually growing in it!
The stump is the only thing remaining of what may have been the parent plant of this young tree. The acorn may have fallen down through the hollow trunk while the tree was alive and remained safe from the squirrels.
As you can see from this photo, the remaining tree stump is huge. In contrast the girth of the little tree is only 115cm.
Despite the growth of this little tree 'from the ashes' , it is not a Phoenix tree. This term is used to describe trees which form by layering - the branches swoop down and root where they touch the soil and then grow into a tree.
The tree is easily spotted next to the footpath