Several winters ago, when we had some very heavy snow around this time of year, my neighbor's snow blower flung quite a bit of the white stuff onto my birch trees. The one pictured above was bent down onto our garage roof. When the snow melted off, the tree recovered only slightly, and we didn't bother to figure out how to straighten it up. During the next couple of years, I noticed something reminiscent of high school biology labs. A few new branches bent and started growing straight up - the new straight up, which would be parallel to the trunks of the tall firs and pines in the background. This response in opposition to gravity is called negative geotropism. (And spell check doesn't recognize that word! Pathetic!) Tap roots exhibit positive geotropism. By standing erect, we are practicing negative geotropism. I suppose one could say that falling down is an example of positive geotropism. Until now, I never thought of anything positive about falling down.
At the time of the heavy snow we had three birch trees. One of them has since bit the dust and only a 3-foot stump remains. I featured that one here a few days ago because of the great growth of Turkey Tail Fungus now decorating it.
This closer view shows how our tilted birch has become a kind of clinometer. (Another word that spell check doesn't recognize!) In the years since the original upward thrust of the new branches, the root system of the tree has started to give way and the main trunk has sunk another few degrees. Note that the branch with the sharp angle has tilted a few degrees off vertical. The older branches to the lower left have only begun to curve upward at their tips. The new branch probably "thinks" it's a new tree.
So, while it's enjoyable to me to share a little bit of knowledge about plant behavior, in the spirit of the late Richard Feynman's The Pleasure of Finding Things Out, I am doing so in a climate of anti-science and anti-knowledge, two terms for the same thing. For more on this topic, check out my next post, probably tomorrow afternoon. I have to take a break to correct some student papers. The next post will be titled "Beware of Knowledge!"
Wednesday, February 4, 2015
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