Thorn bush/tree with oak like leaves?
I'm hoping that someone can help me out here. This bush/tree sprung up in our garden by our pond sometime late last year and we can't figure out what it is!
I'm not sure whether it is a nuisance or something I should hold onto, therefore I would sincerely appreciate it if someone could identify it.
Here are some observations that may help:
It has oak-like leaves, but I'm skeptical that it is a species of oak since it has thorns toward the end of the branches (I drew a black circle around one of the thorns).
It is kind of slender and gangly looking, with leaves growing right up each of the branches. The branches do not branch off into smaller sections either. Over all it is about 5'5" (approx. 165 cm), though it could grow taller as it has grown astonishingly fast in the last year.
The leaves appear to be deciduous as some of them are now starting to change a yellow color (and it is autumn here).
I have yet to notice any fruit or seeds growing on it, but I haven't been closely monitoring either, therefore it may be possible that I missed that cycle.
Contact with the plant does not cause any rashes (ruling out poison oak, sumac, ivy, etc.).
Also I live in Europe!
Hopefully that is enough information for an identification. Thank you in advance!