  Measurements of jet substructure describing the composition of quark- and
gluon-initiated jets are presented. Proton-proton (pp) collision data at
$\sqrt{s}$ =13 TeV collected with the CMS detector are used, corresponding to
an integrated luminosity of 35.9 fb$^{-1}$. Generalized angularities are
measured that characterize the jet substructure and distinguish quark- and
gluon-initiated jets. These observables are sensitive to the distributions of
transverse momenta and angular distances within a jet. The analysis is
performed using a data sample of dijet events enriched in gluon-initiated jets,
and, for the first time, a Z+jet event sample enriched in quark-initiated jets.
The observables are measured in bins of jet transverse momentum, and as a
function of the jet radius parameter. Each measurement is repeated applying a
"soft drop" grooming procedure that removes soft and large angle radiation from
the jet. Using these measurements, the ability of various models to describe
jet substructure is assessed, showing a clear need for improvements in Monte
Carlo generators.
