A clade is a branch (from the Greek). Modern usage has this depict branches in a tree, and cladistics is the taxonomy of the tree of life. Here is the source of the paradigm the chart above fits into
The circle is merely to conserve space – no metaphysics necessary. Notice how at the 5th and 6th level branchings, we se the beginnings of the pattern in the first chart, the one of Christian history?
Am I the only one who appreciates this irony?
Here’s a similar view of Linux distros – notice the children of Ubuntu
The idea is quite useful, because most things in our world fit into some type of hiercharchy, which lends itself to being shown as a tree. I’m a Christian myself, but I find it very amusing that Christian church history itself can be described by a series of 2 way forks – a perfect cladogram.