Plants & Trees (Q&A)

Answer:

Some trees especially deciduous trees and other plants lose their leaves every winter. They drop their leaves because of a weak area (called the abscission layer) at the base of the leaf stalk. When days shorten in autumn the reduction in light triggers the tree to absorb back some of the nutrients in the leaves. The abscission layer then softens and weakens, causing the leaf to die and drop off. This is done by plants to protect themselves during the winter months, as the cold dry winds readily strip moisture from the trees through the leaves, which have a large surface area. By losing their leaves, trees conserve their moisture in the trunk and branches, rather than drying out and dying. The leaf loss puts the tree into a state of dormancy and greatly reduces the amount of energy that the tree needs to stay alive.

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