At times pro-golfers get a bad swing and the ball may well end up stuck in a tree. Well, when that unfortunate event happens there are 3 ways out for a continuing play,
a. Unplayable – Declare the ball unplayable under Rule 28 and take a one-stoke penalty
b. Lost Ball – One-stoke penalty and return to the spot if the previous stroke and replay the shot
c. Play It as It Lies – Meaning, climb the tree, get into a position and take a swing at the ball. By doing so you avoid the one-stoke penalty.
On the tour, where every stroke counts, the process are apt to choose option c – see the famous examples of Bernhard Langer and Sergio Garcia. These guys really do have every swing in their bag!