Fig. 1

Unrooted non-binary phylogenetic network N^u on leaves 1, 2, 3, and 4. The gray areas correspond to the blobs of N^u. Notice that the biggest blob contains a cut vertex (depicted as a square vertex). Moreover, notice that N^u can be considered as a tree with blobs as vertices, as the cut edges and blobs of N^u induce a “tree structure”