Pollard Willow

I know this is a tree, but it sure looks like something different.
I had a walk of 15+ kilometres with our oldest son M. on/in the "Kühkopf-Knoblochsaue" nature reserve. A beautiful and really protected reserve, the largest in Hesse. Close to the entrance it is always quite full with pedestrians and cyclists, but closer to the Rhine it is more empty and nature.
The reserve does have a lot of mistletoe, but also a lot of pollard willows. Most are not that old, but this one, in a group of four is pretty old and hence a bit strange.