Anatomy of a TidyTree

A TidyTree is composed of various nodes, branches, and labels. Generally speaking, a node is a circle, a branch is a line, and a label is some text. It should look something like this:

The top node in the tree (i.e. the one with no parents) is referred to as the "root" node. A node with no descendants is referred to as a "leaf" node. Nodes which do have descendants (including the root node) are called "branch" nodes.

A label hanging off of a branch node is called a branch label. A label hanging off of a leaf is called a leaf label. Go figure.

One special type of label is the "branch distance". It's typically a number that's written on or near the branch itself (rather than adjoining the associated node), and used to indicate the patristic distance represented by the branch.