Coming up in my garden right next to some forest (primarily oak mixed with beech, birch, maple) in southwest Sweden. Last year i dug the area out and removed (most) roots. Not much came up but this little sprout. I suppose it could be roots reaching in from the adjacent forest.
Never seen sugar cane growing in Sweden. Never had that or bamboo here so i doubt it is either. Perhaps there are relatives native to my area. But thanks for sharing your guess!