Flowers smell nice, but their smell is not for people. It is a message to insects and birds that carry pollen.

Scientists have found more than 1,700 kinds of scent chemicals in flowers. Flowers that smell strong at night often call moths. One huge flower smells like rotten meat to call flies. Some orchids even smell like female bees to trick male bees.

Flower scents were not made for humans. They are messages to animals that carry pollen. A 2006 study collected data from about 1,000 plant groups and found more than 1,700 scent chemicals. Each scent is a mixture of several to dozens of chemicals, and changing the mix creates a different message.

Flowers that smell strongest at night are often pollinated by moths, while the giant corpse flower smells like rotten meat to attract beetles and flies. Some European orchids go further. Their scent is almost the same as the sex pheromone of female bees, so male bees try to mate with the flower and carry its pollen away. The orchid gives them no nectar at all.

The fragrances we enjoy in flowers evolved not for us but as chemical messages to pollinators. A 2006 survey of floral scent data from roughly 1,000 plant taxa listed more than 1,700 compounds, mostly terpenes, benzene-ring compounds and substances derived from fatty acids. Because each scent is a blend of several to dozens of molecules, varying the proportions allows plants to target particular visitors.

Timing matters too: many flowers that release scent at night are pollinated by moths, whereas the corpse flower emits a smell of rotting meat to lure beetles and flies. Some signals are dishonest. In 1999, researchers showed that an Ophrys orchid releases compounds nearly identical to the sex pheromone of female bees; males attempt to mate with the flower, pick up pollen and receive no nectar in return.

Scent release is also more active than once thought. In 2017, a study of petunias identified a transporter protein that pumps scent molecules out of cells; when it was reduced, emission fell and the compounds built up in membranes to levels harmful to the cells. Flowers, in other words, spend energy to broadcast their messages.