What Makes Flowers Smell?

By Cindi Pearce

  • Overview

    What Makes Flowers Smell?
    What Makes Flowers Smell?
    When an individual is given a bouquet of flowers or is wandering through the garden in her back yard, the natural instinct is to sniff the flowers. Most flowers smell delightfully good--although there are some stinkers, including marigolds. We derive pleasure from the floral scents, but the scents also serve a purpose in nature. Unfortunately, flowers aren't as aromatic as they once were.
  • Where Does The Smell Come From?

    According to Natalia Dudareva, a flower researcher and an assistant professor at Purdue University whose report appears on Sciencedaily.com, flowers contain volatile compounds that are essential oils, which evaporate in warm weather. These oils combine to produce various and distinctive scents. One of the most volatile compounds is methylbenzoate, which is one of the most abundant scent compounds. These oils are produced by the petals. Because the oils evaporate too readily in warm weather, they are referred to as volatile compounds, according to the Purdue News. A flower's scent is based on the numerous oils produced by that plant's petals.
  • What Purpose Does Scent Play?

    Flowers produce scents because the fragrance attracts pollinators. According to Dudareva, once a flower is pollinated by bees or moths, the flowers shut down their scent. After the plant is pollinated, it is then fertilized. Fertilization further shuts down the scent of the flower. Dudareva notes that it may take a couple of days for a flower to completely shut down its scent production after fertilization because the flower wants to be sure it has been fertilized because it stops producing scent. Hugh Iltis, professor emeritus at the University of Wisconsin-Madison, notes on Sciencedaily.com that the intoxicating fragrance of flowers attracts "lovers," which are the pollinators. These can be birds or insects, even bats. The flower's scent is the red alert to pollinators that the flower is ready to be pollinated. When the bees or moths collect the pollen or nectar, the pollen gets transferred and fertile seeds are created.
    iStockphoto/Timothy Wood

  • Losing the Scent

    Dudareva says that commercial breeding for longevity (shelf life), color and size has had a negative impact on scent production. She believes that there is a trade-off: Bred to have a long shelf life, the flowers don't expend energy on scent production. Quinn McFrederick, a doctoral candidate at the University of Virginia, was interviewed for ABCnews.go.com by Lee Dye regarding the systematic vanishing of flower scents. McFrederick noted that the "scent trail," which used to be able to cover miles of territory, has been significantly reduced. The scent now disappears while still in close proximity to the flower. The outcome is that the pollinators--bees, moths, insects--aren't attracted to the flower because there is little, if any, smell. The pollinators need the flower's nectar to survive. If the pollinators move on, they don't get the nectar that they require and the flower doesn't get pollinated. Air pollution has been cited as one of the reasons flower scents aren't as great as they used to be and why the scents can't travel very far.
  • Recouping the Smell

    Professor Henry Klee of the University of Florida's Institute of Food and Agricultural Sciences reports that there may be a way to get the aroma back into flowers. This discovery was made when Klee and other researchers, including Andrew Hanson, discovered a gene in tomatoes that adds to the tomato's flavor. They believe that this same gene can add to the scent of a flower, according to an article written by Mickie Anderson. Klee and the other researchers determined the gene that makes 2-phenylethanol, a compound commonly known as rose oil. The researchers will try to develop a rose based on this finding that produces a lot of rose oil, which will increase the fragrance of roses. The fragrance in roses has diminished due to extensive hybridization, which made the roses bigger and more colorful but reduced the smell.
  • Benefits

    Dudareva states in the Purdue News that improving the smell of flowers is important--not only for florists, but for the agricultural industry in general. Many crops require pollination that occurs when the pollinators can smell the floral scents. If there is no scent, or minimal scent, this discourages pollination.
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