why leaves really fall off trees ...
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Why Leaves Really Fall Off Trees
by Robert Krulwich, October 30, 2009
You think you know why leaves fall off trees. Well, you're wrong. It's not the wind. It's not the cold. It's because trees use "scissors" to cut their leaves off.
We call this season the "fall" because all around us right now (if you live near leaf-dropping trees in a temporal zone), leaves are turning yellow and looking a little dry and crusty. So when a stiff breeze comes along, those leaves seem to "fall" off, thus justifying the name "fall."
Sounds reasonable, no?
But the truth is much more interesting.
According to Peter Raven, president of the Missouri Botanical Garden and a renowned botanist, the wind doesn't gently pull leaves off trees. Trees are more proactive than that. They throw their leaves off. Instead of calling this season "The Fall," if trees could talk they'd call this the "Get Off Me" season.