Petal

Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers.

Petals are usually surrounded by an outer whorl of modified leaves called sepals, that collectively form the calyx and lie just beneath the corolla.

If all of the petals are essentially identical in size and shape, the flower is said to be regular[3] or actinomorphic (meaning "ray-formed").

Many flowers are symmetrical in only one plane (i.e., symmetry is bilateral) and are termed irregular or zygomorphic (meaning "yoke-" or "pair-formed").

In irregular flowers, other floral parts may be modified from the regular form, but the petals show the greatest deviation from radial symmetry.

In many plants of the aster family such as the sunflower, Helianthus annuus, the circumference of the flower head is composed of ray florets.

Claws are distinctly developed in petals of some flowers of the family Brassicaceae, such as Erysimum cheiri.

[12] Some flowers will also mimic the scents produced by materials such as decaying meat, to attract pollinators to them.

[13] Various colour traits are used by different petals that could attract pollinators that have poor smelling abilities, or that only come out at certain parts of the day.

Insects such as the bee or butterfly can see the ultraviolet marks which are contained on these flowers, acting as an attractive mechanism which is not visible towards the human eye.

One such example of a flower is the pōhutukawa (Metrosideros excelsa), which acts to regulate colour in a different way.

The pōhutukawa contains small petals also having bright large red clusters of stamens.

On the other hand, some flowers produce the smell of rotting meat and are attractive to insects such as flies.

Darkness is another factor that flowers have adapted to as nighttime conditions limit vision and colour-perception.

In New Zealand, such bird–pollinated native plants include: kowhai (Sophora species), flax (Phormium tenax) and kaka beak (Clianthus puniceus).

This plant has its home under the ground acting the role of a parasite on the roots of forest trees.