Corolla

A corolla consists of all the petals of a flower, considered together.

It's worth noting that the flowers of some species lack petals. The flowers of those species may nevertheless have sepals that look like petals, and those may even be brightly colored like petals.

Figure A.  Corolla with five distinct (not fused) petals.
Wild geranium  (Geranium maculatum)

Figure B.  Tubular corolla with four partially fused petals.
Border privet  (Ligustrum obtusifolium)