The Summary Tree Explorer (STE) is a Java application for interactively exploring sets of phylogenetic trees using two coupled representations: a node-and-link diagram and a textual list of common clades. Selection, pruning, filtering, or re-rooting in one representation is immediately reflected in the other. While summary trees are more effective at showing the relationship among clades, they can only show a consistent subset of those that appear in the textual list. Working with both representations mitigates the disadvantages of having to choose just one. STE, along with several sample datasets, is available at http://cityscape.inf.cs.cmu.edu/phylogeny/