I am in the process of doing the druid epic. After I got the 3 items for turn-in to the withered treant in North Karana, I received the heart and the Treant de-spawned (for 2 hours according to the info under him).
I come here, find him up. I hand him the heart and get the following :
Yeka Ias grabs the heart as you toss it to him before realizing what it is. As soon as it touches his hands, his body convulses, a sickly light emanating from his eyes and oozing cracks appearing in his skin. As he melts into the ground, a small glowing ball floats where he once stood.
He de-spawns. My guess is for 2 hours... (I'm much too busy getting on with the epic to wait 2 hours for a re-pop)