Thursday, November 23, 2006

The Giving of Thanks for The Colors of Trees

Photograph by Eleanor Tauber
Long ago, in a small town in the Midwest where I was to live for a year, there was a particular tree across the street from my bedroom window. It was particular because amongst the branches of that tree was a street light. At night each leaf of a particular bough was illuminated in particular detail, a bright spot in a dark night. And as it was a new town, and I was the new kid in a town where there seldom were new kids, any bright spot, even those on the leaves of a tree, was welcome.
Not knowing anyone and having plenty of time to think, to look, to read, to cast about for something, anything, I watched the trees on the street. I watched how they moved with wind, how the raindrops struck their leaves and as Autumn came and the air grew crisp, I watched their many varied greens begin their transformations to red and purple, yellow, orange, and brown.
"Why do the leaves change colors?" I asked. And I was told, "They change because it's getting colder, winter is coming."
"Oh. ", I said.
That made sense, or I thought it did until I noticed the bough next to the streetlight hadn't lost it's green at all. Wasn't the world the same temperature for it than for the others?
Why wasn't it changing? No one seemed to notice and when I pointed it out, they saw it but it didn't catch their curiosity, their lives were far too busy.
Then that bough too began to change but all the other branches even on the same tree had passed through their colors and their leaves had begun to fall. Not on my bough.
Then when walking to school , I began to see that...Wait just a minute, there were other boughs on other trees behaving exactly the same way.
Because each had a streetlight amongst it's leaves. Could it be true? It was something about the streetlight. Heat? The heat wouldn't reach that far. Perhaps, it wasn't the cold spurring the others on, perhaps it was a difference in light that made the difference. This was serious.
People were giving me the bad information.
One of my frowned upon activities which placed me in the "strange" category as a new kid was my habit of reading while walking back and forth to school. So like any good bookworm, I went to the library to find out.
And there in a volume, not tattered from overuse, was the world of green Chlorophyll. The green that masks other colors. When the night reaches a threshold value, the abscission layer of cells goes mad and divides and divides and divides in between the leaf and the twig. But that little spot doesn't get any bigger, rather it becomes so crammed with cells that the route between leaf and tree is blocked off. No minerals can go from the roots to the leaf, no carbohydrates from the leaf to the rest of the tree. The Chlorophyll can't be replaced and as it turns out, Chlorophyll gets sun bleached.
Sun bleached? Who would have thought?
And as the green fades away, the yellow pigments, the xanthophylls and the orange of carotenoids are revealed. They've been there all the time. Quite delightful, hiding in plain sight.
Not so the anthocyanins, the reds and purples, they are manufactured from the sugars trapped in the leaves. As the days get shorter the abscission cells get dryer and corkier, some trees loose their leaves while still colorful. Others may keep them for awhile but all the pigments eventually break down in the light or when they freeze. That is, except the tannins. And the tannins are brown. Then the leaves themselves break down into the soil....
Kicking through the brown leaves on the way to school, I can't help but think how much the people are missing who find leaves an annoyance that must be raked and burned for their sheer messiness. Leaves have gone through an incredible metamorphosis and they too have a use and a mission. And because they have and do, they are always a "bright spot" no matter their color. In fact, when you look very closely at them, just like so many other things, they are downright illuminating.
Donegal Browne

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