|Wednesday What's New: Pollution and the Scent of Flowers|
|Written by Heleigh Bostwick Wednesday, 09 May 2012|
Someone wrote me a few weeks ago asking why some honeysuckle flowers smelled better than others. My response was that sometimes flower fragrances disappeared as a result of hybridization where the fragrance was bred out in favor of other characteristics. I also noted that generally certain flowers were pollinated by insects that were sensitive to flower fragrance while for other pollinators, flower fragrance was less important than say, color. After reading an article titled, “Scentless Spring? Flower Smells Blocked by Pollution” in National Geographic News the other day, I suppose I can add a third reason to the list: Air pollution.
A recent study has reached the startling conclusion that due to atmospheric pollution, primarily from automobiles and power plants, the potency of flower fragrance has been reduced as much as 90% from pre-industrial levels. This is bad news for pollinators and flowers, as well as humans. Pollinators such as bees and butterflies that depend on flower scent to find nectar and at the same time pollinate flowers may be in deep trouble. In fact, their survival may be at stake.
Ozone, the main component of smog, appears to be the culprit. Ozone forms when nitrogen oxides, a byproduct of automobile combustion, combine with sunlight. Ozone affects flower fragrance because it breaks down the volatile scent molecules more rapidly and scents don’t linger in the air as long. Nor do they travel as far as they used to, making it that much harder for pollinators to find them.