  Jets are algorithmic proxies of hard scattered partons, i.e. quarks and
gluons, in high energy particle collisions. The STAR collaboration presents the
first measurements of substructure observables at the first, second and third
splits in the jet clustering tree via the iterative SoftDrop procedure. For
each of these splits, we measure the fully corrected groomed shared momentum
fraction (\zg) and groomed jet radius (\rg). We discuss the evolution of jet
substructure in both the angular and momentum scales which allows for a
self-similarity test of the DGLAP splitting function. We compare the fully
corrected data to Monte Carlo models, providing stringent constraints on model
parameters related to the parton shower and non-perturbative effects such as
hadronization.
