Pollinators and flowers co-evolved over the millennia to play mutually beneficial roles. Pollinators help angiosperms, or flowering plants, reproduce. They carry the genetic information from one plant, in the form of pollen, to another plant of the same species. Flowers provide nectar and pollen on which their pollinators feed. Some flowers even aid insect reproduction by producing a male attractant fragrance for female insects to douse themselves in.
Strategies and Methods
Flowers adapt features to attract particular pollinators. Colorful flowers attract pollinators with visual acuity. Scented flowers attract those with strong olfactory senses. The pattern of the flower helps to not only attract a pollinator, but also use the behaviors of the pollinator to increase the chances for successful pollination. Structure helps support the pollinator. Some flowers have strong perches to support the pollinator, while others are angled and lack a perch to help out hovering pollinators. Flowers pollinated by wind tend to have non-sticky pollen and unremarkable flowers, if any.
Butterflies follow red patterns to find nectar, and need a landing pad. Bees follow red and yellow patters as well as light fragrance. Ultraviolet nectar guides lead bees to the prize. Bats and moths follow scent and feed at night, so their flowers open in the evening. The only visual cue is white or pale blue flowers that shine in moonlight. Orchid wasps are attracted to the female scent of the orchid flower, and pollinate it in an attempt to mate. Flies find flowers that have the repulsive odors of rotting meat and waste, and pollinate them in search of refuse.
Some flowers are a single gender. This is most common in wind-pollinated flowers. The male flower is located higher on the plant than the female flower or protrusions of the plant, and pollen is knocked loose and spread by wind. The flowers of most plants have both male and female parts. The pollinator brushes against the pollen sacs, which are often sticky, in search of nectar. The pollen contains the male genetic code of the plant.
Female flower parts are receptors. They are often sticky, and are touched by pollinators before they can reach the pollen sacs. This reduces the chance of the flower being self-pollinated, since the nectar must come from the previous flower the pollinator visited. Below the stigma (the part that catches the pollen grains) is a style down which the sperm travel to get to the ovary of the female flower.
When a pollen grain attaches to a stigma, it forms two sperm that travel down the style. When the sperm reach the ovary, one sperm fertilizes the egg cell, while the other fertilizes the endosperm nuclei to form the endosperm nuclei. This is called double fertilization, and is the beginning of the formation of the flower seed. The fertilized egg is the zygote, and contains the genetic information for the next generation of the plant.