joekeerys:

Weirwoods are considered sacred to the followers of the old gods. The children of the forest are said to have carved faces in the weirwoods during the Dawn Age, before the coming of the First Men across the narrow sea. It is said that through the faces the old gods watch over the followers and bear witness to important events. The greenseers of the children of the forest can see through the eyes of weirwoods. Since trees have no sense of time, the greenseer can see into the past or present when looking through the eyes of a tree.