Sunday, November 7, 2010

Seasonal Sunday.

Do you know the real reason leaves fall off of trees? It's not because it's cold and they just know it is fall. There's so much more to it than that.

Here in NEW there aren't too many trees that have leaves left on them. Our trees are one of the few that do. We are always the last house raking because ours drop last. I'm not sure if this is good or bad. I was reading a NPR article and learned quite a bit about the topic. Geeze, what I thought I knew.

Peter Raven, president of the Missouri Botanical Garden, explains that it is not the wind that pulls leaves from the trees, but a hormonal change that triggers a signal to sever ties. Really. The hormone change causes a cellular change involving abscission cells. These cells form at each spot where the leaf stems meet the branch. Abscission is made from the Latin ab meaning away and scindere meaning to cut. This is exactly what is does. Reminds me of the word scissors.

You cannot see any of this with the naked eye, but if you carry a microscope in your purse or backpack you may just be in luck. You would see this bumpy ridge of cells lines up getting ready to push away the leaf. The wind just happens to be in the right place at the right time. 

I always wondered why the leaves couldn't just stay on the tree. I mean they would probably freeze to death, but pine trees have been doing their thing for ages and it works for them....I am no botanist and I do not play one on tv. According to the NPR article and Peter Raven, the leaves act as a kitchen staff supplying and cooking food and when work slows down in the fall they need to let the staff go. I guess if they did keep their leaves they would freeze like I thought and this would kill the tree.  

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