Two tall trees, a birch and a beech, are growing in the woods.  A small tree begins to grow between them, and the beech says to the birch, ‘Is that a son of a beech or a son of a birch?’

The birch replies that he cannot tell, but just then a woodpecker lands on the sapling.

The birch says, ‘Woodpecker, you are a tree expert.  Can you tell if that is a son of a beech or a son of a birch?’   

The woodpecker takes a taste of the small tree and replies, ‘It is neither a son of a beech nor a son of a birch.  It is, however, the best piece of ash I have ever poked my pecker into.’