Leaves may get detached from a tree mainly due to two reasons: natural biological processes and physical forces like shaking.
- Natural Leaf Detachment (Abscission Process):
- Trees form an abscission layer at the base of the leaf stem (petiole). This layer consists of cells that secrete enzymes to break down the cell walls holding the leaf to the branch.
- The production of hormones changes with seasons; auxin decreases as daylight shortens, and ethylene increases, weakening the attachment.
- This process allows the leaf to detach naturally, especially in autumn, helping the tree conserve resources.
- Physical Detachment by Shaking:
- When a tree branch is shaken vigorously, the branch moves, but the leaves tend to stay at rest because of inertia (the tendency of objects to resist changes in their state of motion).
- This resistance causes a force on the leaves strong enough to overcome their attachment and causes them to fall off.
- The mechanical stress from shaking breaks the weakened connections, causing leaf detachment.
In summary, leaves detach naturally through internal hormonal and enzymatic changes or can be physically dislodged by external forces causing mechanical stress on the leaf attachments. Both mechanisms reflect how leaves separate from trees under different conditions.
