Fig. 7
From: On Sackin’s original proposal: the variance of the leaves’ depths as a phylogenetic balance index
The only two trees in \(\mathcal {BT}^{*}_{6}\) of type F6 as obtained from the fully symmetric tree B8 by removing 2 cherries: in the left-hand side tree, the cherries (3,4) and (7,8) are replaced by single leaves 3 and 7, respectively, while in the right-hand side tree the cherries replaced by single leaves are (5,6) and (7,8). The left-hand side tree is the maximally balanced tree B6, the other is only depth-equivalent to it