The structure formation and phase behavior of supramolecular hairy-rod polymers consisting of rodlike polymer chains with physically bonded side chains are investigated in the melt state using small-angle X-ray scattering. The supramolecules consist of poly(2,5-pyridinediyl), complexed by methanesulfonic acid to form poly(2,5-pyridinium methane sulfonates), to which octyl gallates are hydrogen bonded. These comblike supramolecules self-organize in rodlike assemblies in a square or oblique lattice or form lamellar structures. Moreover, nematic (solid) and macrophase separated structures are observed. These results are collected in a phase diagram in the high polymer fraction limit and they are in a clear qualitative resemblance with recent theoretical modeling. The differences and similarities between the experiments and theory are discussed.