You cannot avoid noticing at this time of year trees and their leaves. One minute they are there all green and fulsome, the next they are varied shades and falling rapidly to the ground.
It is interesting to note that some trees lose their leaves before others. All deciduous trees lose their leaves each year. During autumn there is less sunlight available for photosynthesis, the green chlorophyl decreases revealing the red and yellow pigments within the leaves.
The tree will lose water needlessly through its leaves, so the sap carrying veins gradually shut down. An abscission zone forms at the base of the leaf consisiting of weak cells in the top layer and tougher ones at the bottom, eventually the weak cell layer is broken and the leaf falls off.
This varies between different trees, for instance beech and oak trees have a very weak abscission layer and often keep…
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