Tree

I may be missing the boat completely, but I think the tree's main purpose is to signify that this is a holiday card.

Our family Christmas trees were always topped by an angel.

There may be significance in the ominous way in which the tree grows.  Perhaps it has something to do with the fragility of memory, or perhaps of emotions during family get-togethers.

There are better things to click on.  And make sure you hit the book inside the bag.  It's important.