I thought that I had found all the puzzles, and only missed the last big tree, but when I got to this tree, I could not do any thing. So I have probably missed something.
How many puzzles have you found? And have you cleared all the trees and bushes? There are 3 Pines, 3 Ipes and 3 bushes areas to clear, 5 Landmark Location puzzles to clear before the Big tree Puzzle show up! It's a total of 14 things to do before you can do the last one!