The part of the flower that is brightly coloured and attract pollinating agents such as insects is labelled

The diagram shows a longitudinal section of a flower with four labelled parts. Label I points to the anther at the tip of the stamen, label II points to the stigma at the top of the style, label III points to the petals (the broad, conspicuous structures surrounding the reproductive organs), and label IV points to the sepal at the base of the flower.

The part of a flower that is brightly coloured to attract pollinating agents such as insects, birds and butterflies is the petal (collectively called the corolla). Petals produce pigments such as anthocyanins and carotenoids that give them vivid colours, and in some species they also produce nectar guides visible under ultraviolet light. These visual signals help pollinators locate the flower and its nectar or pollen rewards, facilitating cross-pollination.

In the diagram, the petals correspond to the structures labelled III.