-ultrametrics because they do not satisfy the identity axiom. The fifth descriptor considered is path difference which is not recommended for comparisons except for unrooted trees. Correlations among dendrogram descriptors are evaluated through simulation experiments, and it is shown that the significance of dendrogram comparisons is greatly influenced by the choice of the descriptor. The paper emphasizes that choice of the underlying tree distribution to be used as a reference in testing significance of a dendrogram comparison measure should be consistent with the descriptor incorporated by that measure.