"Stepping through the items of a tree, by means of the connections between parents and children, is called walking the tree, and the action is a walk of the tree. Often, an operation might be performed when a pointer arrives at a particular node. A walk in which each parent node is traversed before its children is called a pre-order walk; a walk in which the children are traversed before their respective parents are traversed is called a post-order walk."
The above is from one of Wikipedia's articles on "trees". Seems funny, but familiar?
Here is an article about the "oldest tree" found so far. It goes a bit against our usual "pattern" of trees as well.
Not so this one here, I assume. Just another patterned Christmas tree: