Tuesday, September 12, 2006

Further adventures in tree knowledge.

Looking at pictures from yesterday, before the rain came back to soak us all day today, it occurs to me that I no longer know--if ever I did--why leaves turn red in fall. And so I do what any couch-bound questioner does: I google. And I learn, among other things, that red pigments, caused by anthocyanins, may be a tree's last gasp to protect itself from an overdose of light, once its leaves' metabolism starts to decline. And I also learn that some French scientists have hypothesized that brilliant leaf color may serve some of the same functions as the bright hues of male birds' plumage. It may be the case that my trees are showing off so that our remaining insects won't regard them as vulnerable, able to be picked off or decimated. I love that possibility. Perhaps I should throw out some red leaves, somehow.


Blogger Poking-Stick Man said...

My understanding had always been that, with the approach of colder temperatures, trees gradually withdraw the chlorophyll from their leaves, exposing the pigments its green formerly obscured. But I could be wrong.

2:13 AM, September 13, 2006  
Blogger Dr. S said...

Apparently that may be the case for leaves that turn yellow, but not for red. And it may not be a withdrawing so much as a shutting down of the ability to produce chlorophyll.

Not that either of us is a tree specialist!

7:19 AM, September 13, 2006  

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