Flowers Built for Their Visitors
Flowers are not decorations. They are a plant's way of making seeds, and for many plants, seeds begin only after pollen moves from one flower to another. This movement is called pollination. Plants cannot walk to find a partner, so many of them rely on animals to carry pollen for them.
A flower pays its visitors with food, usually nectar, a sweet liquid, and sometimes extra pollen. While an animal feeds, pollen sticks to its body and rubs off on the next flower it visits. The shape, color, and scent of a flower are tuned to the kind of visitor it wants.
Compare two examples. A flower pollinated by bees is often blue, purple, or yellow, has a place for the bee to land, and gives off a sweet smell. Bees can see ultraviolet light, which people cannot, and some flowers have patterns that show up in that light and point toward the nectar. A flower pollinated by hummingbirds is often red or orange and shaped like a tube, with the nectar deep inside. These flowers usually have little scent, and the long tube suits the bird's long bill and tongue.
Some flowers have even more specialized partners. Many bats visit pale flowers that open at night, and moths pollinate flowers whose strong scent fills the evening air. Because each visitor needs the flowers, and each flower needs the visitor, the loss of a pollinator can affect the plants that depend on it, which is one reason people work to protect bees and other insects.
Not all plants use animals. Grasses and many trees release large amounts of light pollen that the wind carries, so their flowers are small and plain. Each strategy works for the plant that uses it.