I don't know what the plant is - maybe a sapling of sime kind. But what has happened? This is not a fuit - too large and irregular shaped. Is it a fungus? Maybe it is an insect parasite like a bedegar (we had lots of bedegars last summer)?
these are clearly galls on what looks like a small Poplar sapling/sucker. There may be more than one causative agent present here - the rolled leaves (which significantly aren't hairy) and the large infl;ated structure. Lots of different organisms can elicit characteristically shaped responses from their chosen host. I'm afraid I'm not really good at/into galls - many on Poplars seem to be caused by woolly aphids of the genus Pemphigus.
Yes I found these two possible culprits. First as you say something like Pemphigus spyrothecae and the second Thecabius affinis. As you say there seems to be more than one thing that could have caused this problem for this poor tree