This paper presents examples of star-forming phenomena in the discs of spirals which show symptoms of phase-coherence over kpc scales. Cases are found where, along an arm, the youngest blue stars are coherently displaced from a recent but older generation of redder evolved supergiants; in other cases, the star formation efficiency in arms appears to be responding to a density wave resonance pattern. Cases were also found with axisymmetric outflow in the disc components of circumnuclear starburst zones, which could account for an evolutionary starburst-LINER sequence.