A plant reproduces through its flowers. A Flowers can contain either the male or female organ or both together.
Flowers have brightly coloured petals or sepals. The reason why flowers are so brightly coloured and perfumed is to attract insects.
Insects play a very important part in pollinating them. Some plants also produce a sugary liquid called nectar, which attracts the bees. As insects fly from flower to flower, they help to transfer the pollen to the stigma of the flower, resulting in fertilization.
Below Flowers info from Wikipedia (Read More):-
Plants can not move from one location to another, thus many flowers have evolved to attract animals to transfer pollen between individuals in dispersed populations. Flowers that are insect-pollinated are called entomophilous; literally "insect-loving" in Latin. They can be highly modified along with the pollinating insects by co-evolution. Flowers commonly have glands called nectaries on various parts that attract animals looking for nutritious nectar. Birds and bees have color vision, enabling them to seek out "colorful" flowers. Some flowers have patterns, called nectar guides, that show pollinators where to look for nectar; they may be visible only under ultraviolet light, which is visible to bees and some other insects. Flowers also attract pollinators by scent and some of those scents are pleasant to our sense of smell. Not all flower scents are appealing to humans, a number of flowers are pollinated by insects that are attracted to rotten flesh and have flowers that smell like dead animals, often called Carrion flowers including Rafflesia, the titan arum, and the North American pawpaw (Asimina triloba). Flowers pollinated by night visitors, including bats and moths, are likely to concentrate on scent to attract pollinators and most such flowers are white.
http://en.wikipedia.org/wiki/Flowers
