Most plants reproduce the next generation of flowers by making seeds. This is sexual reproduction, because it requires that genetic material be exchanged between two parent plants. Flowers are reproductive organs of a plant. Most flowers have male and female parts. Male parts are called stamens; anthers at the top of stamens produce pollen. Female parts called carpels are where the eggs (or ovules) are made.
The pollen produced by the flower contains the plant's male sex cells. For fertilization to take place, pollen must be transferred to the carpel by another flower. A pollinating agent, such as an insect, bird or even the wind, must transfer pollen from one flower to another. Flowers have evolved different features such as bright colors and sweet scents to attract pollinators.
Most pollinators are insects. They're able to feed from the flower's nectar, which is located at the bottom of the petals. In doing so, they come into contact with the pollen and carry it away to the next plant at which they feed. Some flowers are pollinated by birds, such as hummingbirds, or even bats such as the fruit bat. Some plants pollinated by night-flying moths only open their flowers at night. If a flower relies on the wind to transfer its pollen, its appearance is less noticeable because it doesn't need to attract its pollinator. Most trees and grasses are pollinated by wind.
Flowers vary in their structure. Some have a simple structure that allows them to be pollinated by many different types of animals; some have a specialized structure and therefore are dependent on one particular type of animal for pollination. The daisy, which uses a variety of different pollinators, is an example of a simple structure. The sweet pea is a complicated flower structure, because only bees can get inside the petals to find its nectar.
Fertilization occurs after the plant is pollinated. Pollen is joined with the ovule inside a seed, and genetic material in the two parts combine. After fertilization, the plant's female organs develop fruits or seeds. Plants use a variety of methods to then disperse their seeds. There's a miniature plant inside the protective covering of the seed that develops when conditions are right.