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No, don’t call this season “Fall”; we’ve got a better name: “Get Off Me!”

September 21, 2006 1:15 PM

Correspondent Robert Krulwich blogs about tonight's piece:

They call it “Fall”, after all. Which would lead anyone normal to believe that what happens this time of year is: The days grow shorter. The sun travels lower in the sky. Temperatures cool. The wet, green moist trees of summer get a little drier, they weaken their grip; their leaves dangle, then along comes a stiff breeze and whoooosh, the leaves fall off, carried away by a breeze. That’s what you think, no? That’s certainly what I thought, until I learned otherwise.

Our story on World News describes what’s really going on.

Trees, it turns out, don’t just shrug and let their leaves drop.

Trees (certainly most deciduous or leafy trees in the American and Canadian northeast) send a hormonal message to virtually every leaf on the tree – and that’s a whole lot of leaves---that cause each and every leaf to turn on a set of cells that perform a scissor-like operation that cuts a little seam down where the leaf meets its branch, thereby loosening the leaf so it is barely hanging on.

Then, the wind does its work.

So, as I say in the story, from the tree’s point of view, this isn’t really the “Fall” season; this is the “Get Off Me!” season

Want proof?

On the broadcast we take a summer-green branch of leaves, stick ‘em on my office shelf like a book, no water, wait a few months till they are dry and dusky and then place them in front of a powerful propeller.

I won’t tell you what doesn’t happen next.

Just watch.

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