The role of flowers in the life of a plant is sexual reproduction. That is, to get pollen from one flower to another and spread the parent's genes. Flowers develop their individuality and unique characteristics in order to achieve pollination, often relying on birds or insects to do it for them. This has lead to some rather extraordinary kinds of flowers to lure in their pollinators.
The flower of Rafflesia arnoldii is the largest single flower in the world at up to 3 feet in diameter and it smells like rotting flesh. It is native to the warm tropical jungles of Borneo, Sumatra and Java where it lives as a parasite in Tetrastigma vine roots. The actual body of the plant is thread-like and grows inside the host's tissue and is not visible other than when flowering. The flower starts as a small woody knot on an exposed root on the forest floor. It eventually swells up and resembles a wooden head of cabbage. When it opens, it is red, speckled with white and has five petals, The center is a hollow dome from which the putrid smell emanates. The purpose of the odor is to attract carrion flies which are its pollinator.
Most flowers attract a pollinator by luring them with a promise of food. They do this with sweet nectar, showy flowers and sweet or foul smells. One flower, the ophrys orchid of Europe, uniquely uses sexual cues instead. The modified petal called a lip mimics the furry abdomen and color patterns of various species of female wasps and solitary bees. Each species of orchid has a flower that is adapted to a specific species of insect. The flowers also emit sex pheromones that are similar to the female insects of the species it is targeting. This attracts the males and they are fooled into trying to mate with the flower, which is called psuedocopulation. During the process the males get pollen attached to their body. They then fly to another flower and deliver the pollen.
Calimyrna fig trees, like the other figs, have one of the most unique types of flowers in the plant kingdom. We know these figs as the edible kind we eat dried and in fig-filled cookie bars. When immature, the fruit of the fig is a hollow egg-shaped sphere with a small hole at the end and is actually not a fruit at all. The flowers of the fig are minute and grow on the inside of the shell of the sphere, never seeing the light of day. Female fig wasps enter the hole, lay their eggs then die. The shell of the sphere swells into the flesh we eat and the hole is closed. The wasp eggs then hatch inside the now fleshy shell and immediately mate. The males then die inside the fig. The females exit the shell through chewed holes and get covered with pollen by the internal flowers in the process. They then fly to an immature fruit, enter through the open hole, then deposit the pollen and lay more eggs. Each pollinated flower inside the shell eventually creates one seed.