Embracing Autumn’s Fragrance
If you know, you know. The aroma of autumn cannot be mistaken, at least not for me. It stops me in my tracks. Suddenly, I am 13 again, riding my Huffy, delivering newspapers in the cool, crisp afternoon. I smell the scent of sweet, warm sugar filling my nostrils as I try to make my inhale last a little longer, hoping to extend every second of breath.
If you’ve ever wondered why autumn smells the way it does, it’s due to the fallen leaves of the deciduous trees beginning to decompose. The sugars and other compounds in the leaves give off that unmistakable scent. And if you are like me, it creates such an intense emotion because we associate it with our memories as kids growing up, playing in leaf piles, riding bikes along woodland trails, or simply helping mom and dad rake leaves in the backyard.
These emotional memories and associations with smells are stored in specific parts of the brain. When the aroma molecules enter our nostrils and trigger this part of the brain, fireworks ensue. Those feelings of nostalgia and happiness (in my case with autumn) wash over me and in that moment, I am transported to another time and place.
The smell of fall intensifies after a short rain or on a dewy morning. This is most likely because water helps the decomposition process and emits more aroma molecules. I am fortunate to work near a wooded area with a mixture of oaks, hickories, maples, and sweetgums. Their cornucopia of reds, oranges, golds, and purples is just at its peak as I write this, and the fallen leaves are scattered around the parking lot and sidewalks, filling the air with their earthy sweetness.
A similar aroma comes from a well-done compost pile. A good compost does not stink. The organic compounds and sugars break down similarly to fallen leaves and give off a slightly sweet smell. But let’s talk compost another time.
Certain trees have a very distinct aroma to their leaves. While attending Temple University, our Woody Plants professor would take us on campus walks to pick out the specific dozen or so trees and shrubs that were being discussed each week. She always had a story for every specimen, which actually helped us remember every plant.
For example, outside Dickinson Hall at the Ambler Campus, there stood a picturesque Katsura tree (Cercidiphyllum japonicum) with its large, bending branches filled with heart-shaped leaves and tiny banana-shaped seed pods. It turns a brilliant yellow in the fall and its leaves smell like caramelized sugar and cinnamon. In Germany, they are named after how they smell: Kuchenbaum or Lebkuchenbaum which translates to “pie tree” or “gingerbread tree.” Yes, please. You had me at “pie.”
Every fall semester, I walked by with anticipation each day until the leaves started to turn their golden hue and drop to the ground beneath. It was almost a ritual to get close and take a deep breath on those chilly autumn days. Students of disciplines other than landscaping and horticultural most likely did not know what was causing the scent to waft in the air. But we did.
Trees impact our senses with more than just visual beauty. They whisper to us when the wind blows; they can be rough or smooth or prickly or crinkly to touch; they provoke memories with their fragrance, often just when we need them to lift our spirit. Trees have a lot to offer; maybe we should give them thanks this holiday season.
Stay warm this Thanksgiving, and let’s garden together! ▼
Eric W. Wahl is Landscape Architect at Pennoni Associates, and President of the Delaware Native Plant Society.