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Floral Fragrance | Making Scents

Clipart of bee smelling a flower Flowers of many plant species produce a scent. This scent is typically a complex mixture of compounds emitted by flowers into the atmosphere.

The structure, color and odor of flowers are critical factors in attracting pollinators. Although flowers can be identical in their color or shape, there are no two floral scents that are exactly the same. Floral fragrance is a signal that directs pollinators to a particular flower whose nectar and/or pollen is the reward.

Volatile compounds emitted from flowers function as both long- and short-distance attractants and play a prominent role in the localization and selection of flowers by insects, especially moth-pollinated flowers, which are detected and visited at night.

A flower's scent is created within the petals where essential oils are stored. When there is warm weather, the oils combine and evaporate, producing a unique scent for every flower to attract pollinators.

Why Do Flowers Produce Scents?

Flowers produce a unique floral musk to signal pollinators that the flower is ready for fertilization. Insects such as bees and butterflies are drawn into the scent. By going from flower to flower, the insects fertilize the plant by transferring pollen from one flower to another.

For a plant to enable and foster the tendency of pollinators to specialize, it must provide them with a reliable cue representing the best means of identifying its flowers. Many pollinators learn these signals to predict those flowers offering the highest quality rewards

Species pollinated by bees and flies have sweet scents, whereas those pollinated by beetles have strong musty, spicy, or fruity odors. There are no two floral scents that are exactly the same because of the large diversity of volatile compounds and their relative abundances and interactions.

To date, little is known about how insects respond to individual components found within floral scents, but it is clear that they are capable of distinguishing among complex scent mixtures. However, flower fragrances facilitate an insect's ability to learn particular food sources, thereby increasing its foraging efficiency. At the same time, successful pollen transfer (and thus, sexual reproduction) is ensured, which is beneficial to plants.

The creation of scent is a balancing act: plants must generate enough smell to induce insects to fertilize their flowers, but not so much that they waste energy and carbon. In fact, for many species, scent emission is not constant; snapdragons decrease scent production 36 hours after pollination.

How Is The Floral Scent Created?

A flower's scent is created within the petals where essential oils are stored. When there is warm weather, the oils combine and evaporate, producing a unique scent for every flower to attract pollinators.

The part of the plant that releases fragrance depends upon the species. For many flowering plants, the production of odor is not confined to one area, but is spread throughout the outer layer of petals and other parts of the flower. But some flowers, such as orchids, have specialized scent glands called osmophores that ooze liquid scent, which evaporates on contact with the air.

Plants tend to have their scent output at maximal levels only when the flowers are ready for pollination and when its potential pollinators are active as well. 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. Once a flower has been sufficiently pollinated, quantitative and/or qualitative changes to the floral bouquets lead to a lower attractiveness of these flowers and help to direct pollinators to un-pollinated flowers instead, thereby maximizing the reproductive success of the plant.

How Do Insects Detect Floral Scents?

Insects don't have noses the way mammals do but that doesn't mean they don't smell things. Insects are able to detect chemicals in the air using their antennae or other sense organs. An insect's acute sense of smell enables it to find mates, locate food, avoid predators, and even gather in groups. Some insects rely on chemical cues to find their way to and from a nest, or to space themselves appropriately in a habitat with limited resources.

Insect pollinators can learn and remember floral scent in the context of nectar foraging and that plays an important role in the evolution of plant–pollinator relationships.

Further Information:

 Wisconsin Native Fruit Trees
 Wisconsin Native Berry Shrubs
 Lovely Native Violets
 Use Eggshells For Your Plants
 How to Use Banana Peels in Your Garden