You find solace in the green, can grow defensive thorns, and can communicate with plants.
Wooden Fist (Su): As a free action, your hands can become as hard as wood, covered in tiny thorns. While you have wooden fists, your unarmed strikes do not provoke attacks of opportunity, deal lethal damage, and gain a bonus on damage rolls equal to 1/2 your cleric level (minimum +1). You can use this ability for a number of rounds per day equal to 3 + your Wisdom modifier. These rounds do not need to be consecutive.
Bramble Armor (Su): At 6th level, you can cause a host of wooden thorns to burst from your skin as a free action. While bramble armor is in effect, any foe striking you with an unarmed strike or a melee weapon without reach takes 1d6 points of piercing damage + 1 point per two cleric levels you possess. You can use this ability for a number of rounds per day equal to your cleric level. These rounds do not need to be consecutive.
Pathfinder RPG Core Rulebook. Copyright 2009, Paizo Publishing, LLC; Author: Jason Bulmahn, based on material by Jonathan Tweet, Monte Cook, and Skip Williams.