Taking a stance and playing the ball
From “Golf The Ultimate Guide” DK Publishing, 2014
“One of golf’s fundamental rules is that you should play the ball as it lies—in other words, in the same position where it landed. There are serious implications if you attempt to improve your lie or the area of your intended swing through the ball in any way.”
Ball Identification … The rules allow you to bend back grass in heavy rough in order to identify your ball Playing away from obstructions … If you are unlucky enough to have to take a shot from behind a tree, you might need to improvise. Golf sometimes requires imagination as well as skill.
You aren’t allowed to force branches away with your hands or stamp down on them to prevent them from impeding your shot. The rules do permit you to carefully ease yourself into a position to play the shot. This is known as “fairly taking your stance,” and it simply means doing what is reasonably necessary to get into a position to make a swing at the ball.
If by some dire stroke of misfortune your ball becomes lodged up a tree, you are allowed to shake the branches or even throw a club at it in an attempt to bring it back down. Just don’t risk getting your club stuck in in the tree too!