The sequential line plot of topological resonance energy (TRE) against the number of pi electrons (N-pi) for any polycyclic aromatic hydrocarbon (PAR) is very similar with the same number of extrema to that for benzene. Thus, global aromaticity of a PAR molecular ion strongly reflects that of a benzene molecular ion. Likewise, the N-pi dependence of TRE for any polycyclic pi system formed by fusion of two or more rings of the same size reflects that for a monocyclic species of the same ring size. In general, TREs for such polycyclic pi systems and their molecular ions can be interpreted consistently by reference to those for neutral and charged monocyclic species of the same ring size.