Which set does this lego tree belong to?
The stalk mold comes in two green versions 6097232: Stalk W. 1,5 Shaft And 3,2 Shaft and 6269940: Stalk W. 1,5 Shaft And 3,2 Shaft
Looking through photos of the sets containing these green parts, which contain some kind of tree build gives two sets:

10253-1: Big Ben
10247-1: Ferris Wheel

It's not the Big Ben set as this set contain a small tree which is build using a 1x1 plate:

The Ferris Wheel has a similar tree as you have and it also contains the same white
6170419: Stick 6M W/Flange (white ring on your photo):

Only your tree is missing a second cone piece. So it is hard to tell if this tree is coming from the Ferris Wheel set or someone used that tree build to build their own.