Not sure about this one either. I don't think I've seen one of these yet. I may be able to ask someone at the Kumpula Botanical Garden here in Helsinki if we can't find any answers here on permies.
Pin cherries (Prunus pennsylvanica) are round and translucent, but this doesn't quite look like a pin cherry. But the bark and leaves do scream Prunus.
Vic Johanson
"I must Create a System, or be enslaved by another Man's"--William Blake
"Don't believe every tiny ad you see on the internet. But this one is rock solid." - George Washington
Heat your home with the twigs that naturally fall of the trees in your yard