The autumn trees dazzled us this fall.
I am also dazzled every spring when the vibrant neon greens appear. The miracle of it. The science of it, which fascinates me and has taught me something about my own life.
It’s the hours of the daylight that trigger most of what happens to deciduous trees. New tree leaves produce a remarkable pigment—chlorophyll, which can absorb wavelengths of nearly all the colors found in sunlight. The only wavelength in the spectrum this pigment is not able to absorb is the one reflected back to our eyes—that beautiful, leafy green.
There are other pigments in the leaves, but none absorb sunlight as well as chlorophyll. They are hidden by the dominant green.
Chlorophyll is not so stable, though, and keeps breaking down. A tree must expend energy to constantly regenerate this pigment. Sometimes chlorophyll is described as an “expensive” pigment, but its light-catching ability is apparently worth its cost when the tree is in full food production and needs all the wavelengths it can get.
The leaves are a wonder. They allow evaporation which initiates a steady flow of water from the roots to the canopy through the tree’s vascular system.
(Microscopic view of chloroplasts in leaf tissue)
Within each leaf’s cells are disc-like chloroplasts (factories, really). Powered by energy from the sunlight, they transform water and carbon dioxide from the air into the sugars needed for growth--the process of photosynthesis. Fortunately for us, oxygen is released back into the air.
The diminishing sunlight of late summer triggers a shift in the trees long before most of us notice it happening.
I like the poetic way Maria Popova describes it:
“As daylight begins fading in autumn and the air cools, deciduous trees prepare for wintering and stop making food — an energy expenditure too metabolically expensive in the dearth of sunlight. Enzymes begin breaking down the decommissioned chlorophyll, allowing the other pigments that had been there invisibly all along to come aflame.”
There are a variety of accessory pigments, which had always been present in the leaf but unseen. However, two main types tend to have their “15 minutes” of flame.
Carotene, a stable pigment, reflects hues of yellow and orange. When a tree is stressed, it slows down sugar production, and chlorophyll is not replenished. But the carotene remains and leaves turn pale yellow.
Anthocyanin is a water-soluable pigment responsible for reds and purple-blue hues in plants and fruits. It dissolves in the leaf's cell sap.
Some years have perfect weather for bright reds. Warm sunny days encourage sugar production. But dry, chilly nights and narrowing veins trap the sugars in the leaves. A heavy concentration of sugars and high acidity cause the anthocyanins to go wildly crimson.
< Some years are simply beautiful.
And then there are years when those anthocyanins and carotenes dazzle!
I am in my autumn of life, and I feel more akin to the trees than ever.
I can see how my younger neon-green self of spring had soaked in the light of a whole spectrum of possibilities. My energy focused on the dreams and goals of a young person--raising children, tending to careers, and venturing into unexplored ideas and places. There were times when pale yellow leaves marked setbacks, but somehow I found my way to autumn.
Something has shifted. Wintering is ahead of me. And I’m learning that the tree thinks differently in the fall. It is time to decommission my chlorophyll goals of youth.
Those goals break down naturally. Most of us rail against that happening, fretting that we can’t juggle ten balls at once anymore. Our acuity diminishes. Sometimes we feel cheated that there isn’t time left to complete goals we had set for ourselves when we were young.
How often we approach this stage of life thinking that we'll “taper off” our craving for the chlorophyll fix. We imagine new activities that will “keep us busy,” as if the pace we keep defines our worth.
Our challenge in the autumn of life is to become more like the deciduous tree of
a temperate climate.
1) The tree tells us that a slower, gentler pace is necessary. It is time to conserve our resources and let the chlorophyll diminish.
2) The tree shows us that there are other pigments still left in our leaves. Ones that reflect different colors of our personalities. When conditions are right, perhaps those pigments will dazzle, but it is perfectly fine to be “simply beautiful” in an ordinary kind of way.
3) The tree teaches us how to embrace the winter stage of life in a natural way. It retains a vitality within, even as it releases its leaves. In winter the physical things we’ve done so easily in the past may not even be possible now. When the many ways we’ve identified ourselves are stripped away, it is good to know there is still vibrancy in our inner world.
I hope to become more like a tree as I move toward winter.
~K. L. Kurtz
Photos of the University of Guelph Arboretum are courtesy of Paul Benedetto.
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