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na3than t1_iu9de9g wrote

Reply to comment by iDarick in Eli5: What causes leaves to fall off trees? by ShookeSpear

That doesn't answer the question. What causes an attached leaf--one in which there is a bond between the leaf stem and the branch--to become an unattached leaf?

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iDarick t1_iu9dn10 wrote

On nature you drop off what's unnecessary for survival process. So the leaf do it's job and leaves.

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na3than t1_iu9dr3h wrote

That still doesn't answer the question. What causes an attached leaf--one in which there is a bond between the leaf stem and the branch--to become an unattached leaf?

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iDarick t1_iu9e0t0 wrote

The mechanism is called abscission - a layer of cells in the stalk of the leaf swell up and die, weakening the stalk so that the wind will dislodge the leaf. Before this happens, the tree draws resources out of the leaf (senescence), which causes the change in colour from green to browns and reds.

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iDarick t1_iu9e3ra wrote

Some folks have no chill huh

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iDarick t1_iu9e91q wrote

I thought that's ELI5, not biology sub mate, sorry for that.

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ShookeSpear OP t1_iu9foqt wrote

I suppose I chose the wrong sub then. I understand the conservation of energy and nutrients required by a tree for the dormant phase of its growing. I was looking for your very specific answer about abscission. So thank you for that!

My theory relating to the sudden heating of the petiole does make it seem like I have at least a 6 year old’s understanding of tree biology, so probably the wrong sub…

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