So, I live in France, and about a month ago I found a sprouting helicopter seed of some sort in my garden, so I planted it in a pot and now it's grown and I can't identify it.
It is probably a pine tree judging from the needles, but it is too early to identify it positively. Did the seeds look like this? That is Pinus Patula, a pine with winged seeds. If you plant it in a perforated plastic pot, 10-15 cm i diameter, and dig down the pot in the garden you can let it grow until it's identifiable. Then if you like to keep it you let it be and the roots will grow freely out from the pot. But if you want to remove it, then the pot makes it easier to cut the roots that pertrude.