From what I understand, trees aren't necessarily sorted like that guys [ 0, 1, 2, 3... ]. ...that would be just be a flat list then. Trees are good for fast searching and whatnot so it could be in any order (actually that's all my experience with them is; create a node when you discover an item you want to store and keep adding to the tree as you keep parsing--add nodes; small on the left, and big on the right-).
About nodes, each node can contain as much information as you want. However the bigger the node the more memory usage. I'm working on a node right now where I'm storing all the integers in a tree and in each node I store the int and two char strings and an enum (another int).
I have been looking at these pictures and from what I can see, this looks like a simple association list kind of thing (I think).