Pollen is the plant equivalent of sperm, according to the University of Wisconsin-Madison. When a bee or another insect visits a flower, it picks up pollen. As these pollinators continue visiting more flowers to drink nectar or gather pollen, they deposit some of the pollen on the flowers, which then fertilizes them.
Some flowers use wind or simply gravity to aid in pollination, but many plants rely on pollinators. That's where their smell comes in. Flowers produce fragrances to help attract pollinators.
No two flowers emit the same fragrance, according to Scientific American. That's because scents are created by a variety of volatile organic compounds. The amount of these compounds and how they interact with each other is what creates a particular fragrance.
Plants tend to emit the most fragrance during the time of day when the insects they use for pollination are active, Scientific American reports. Flowers that use butterflies and bees for pollination are most fragrant during the day, while plants that are pollinated by moths are most fragrant at night. Some flowers rely on one particular type of insect for pollination, so their scent is very specifically aimed at attracting that insect.
Not all flowers emit a sweet-smelling odor to please people and pollinators alike. Plants that maximize their output during the day are primarily pollinated by bees or butterflies, whereas those that release their fragrance mostly at night are pollinated by moth and bats. During flower development, newly opened and young flowers, which are not ready to function as pollen donors, produce fewer odors and are less attractive to pollinators than are older flowers.
Sign up for our email newsletter. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Go Paperless with Digital. The luscious aroma of flowers attracts lovers, and the biological role of that smell is similar: to attract pollinators. Pollination is the transfer of pollen the plant equivalent of sperm to eggs. Some plants rely on wind or gravity, but many require animals to do the transportation.
Plants and pollinators often display a long history of mutual evolution, Iltis adds. This moth was discovered more than a century later!
The minty, oily or sharp smells produced when you crush a leaf or stem play a defensive role, Iltis says. These smells come from chemicals that are often toxic to animals, and thus serve as a one-two punch: they smell and taste terrible, and then they make you sick if you ignore your senses and take a bite.
During the long struggle for existence, Iltis says, evolution has shaped every part of plants — including their chemical composition.
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