Something in the air
This is such a delightful time of year, with plants bursting into flower and leaf, making the landscape come alive again. But would spring be quite as wonderful if it didn’t smell so good? How many of us plant flowers for their fragrance as much as for their visual appeal? I’m thinking hyacinths, magnolias, lilies, lilacs, irises, roses, lily-of-the-valley, heliotrope, viburnum, honey locust, honeysuckle, jasmine.
A few days ago, after burying my face in yet another iris bloom to inhale its spicy sweetness, I started to wonder, “What is fragrance? When we smell a flower, what is it that we’re actually smelling?” In all the botany I studied in college and all the exploration of the plant world that I’ve done since then, I’ve never come across an explanation. Nowhere in the 748 pages of my college botany text was the subject of fragrance even mentioned.
I wanted to explore the mystery of how something so intangible could affect my senses. Touch, sight, and taste seem straightforward: there is an object that one comes in contact with. Even with sound there is something tangible there; we can feel the vibration. But smells hover unseen in the air, and with flowers the fragrance is tantalizingly ephemeral.
I found the best explanation in an online article, “Making Scents: The aromatic world of flowers,” by Ben Guarino, (http://scienceline. org/2013/01/making-scents-thearomatic-world-of-flowers/). Formerly a freelance science journalist, Guarino now writes for the
Not surprisingly, fragrance comes down to chemistry. Says Guarino, “Each scent compound is an organic molecule known as a volatile, a chemical that vaporizes into a gas when released by a plant.” He describes these molecules as miniscule, so tiny that that they can be sensed by the olfactory organs of creatures as small as the insects that are enticed by aromas to pollinate the plants producing the fragrance.
The scent molecules have “spines” built of carbon atoms. “What makes floral scents distinctive are the length of the carbon chains and the other types of atoms glued to these backbones,” notes Guarino. For instance, on the stinky side of things, it’s sul-