  Northern Galactic Planetary nebulae (PNs) are studied to disclose possible
correlations between the morphology of the nebulae and the evolution of the
central stars (CSs). To this end, we have built the best database available to
date, accounting for homogeneity and completeness. We use updated statistical
distances, an updated morphological classification scheme, and we calculate
Zanstra temperatures for a large sample of PNs. With our study we confirm that
round, elliptical, and bipolar PNs have different spatial distributions within
the Galaxy, with average absolute distances to the Galactic plane 0.73, 0.38,
and 0.21 kpc respectively. We also find evidence that the distributions of the
central star's masses are different across these morphological groups, although
we do not find that CSs hosted by bipolar PNs are hotter, on average, than CSs
within round and elliptical PNs. Our results are in broad agreement with the
previous analyses, indicating that round, elliptical, and bipolar PNs evolve
from progenitors in different mass ranges, and may belong to different stellar
populations, as also indicated by the helium and nitrogen abundances of PNs of
different morphology.
