What is the collection of petals on a flower referred to as?

The collection of petals on a flower is referred to as the corolla. The corolla is an important part of a flower's structure, typically serving to attract pollinators through its color and fragrance. It is composed of individual petals, which are often bright and vividly colored to entice insects and other pollinators.

In contrast, the calyx comprises the outermost parts of a flower, which are the sepals that protect the developing bud. The petiole is actually the stalk that connects the leaf to the stem, and it does not pertain to any part of the flower itself. Thus, in the context of flower anatomy, the corolla is the correct term for the collection of petals.