Deciduous Trees

Deciduous trees are those that shed or drop their leaves in the autumn or fall as it is known in North America. 

In the dictionary the term "deciduous" means shedding leaves annually, or periodically or normal shed.

These trees no longer need to keep the leaves so in autumn they begin to get ready to fall. When they get ready the leaves turn the most beautiful red, yellow, orange or golden colours. This makes the countryside look lovely and when viewed from a height the land can look like a patchwork quilts with the patches of colour.


How do deciduous trees shed their leaves?

The process of starting to shed leaves is called abscission which means "to cut".

This shedding is intentional that is it is suppose to happen plants drop their leaves and maybe their flowers after fertilisation has take place to allow the fruit to grow like on an apple tree.

Where the leaf joins the stem or branch by a little stalk is called a petiole. This is a part in deciduous trees that is called a separation or abscission area.

The upper cells in this area are weaker than the lower cells. In autumn the lower cells expand or get bigger which breaks the cell walls in the  upper cells causing the leaf to fall.

There are three stages to shedding leaves

Resorption

This is where the nutrients which are found in chlorophyll are returned back to the main plant and distributed to other parts. 

This process gives the change in colour as the yellow, red and orange pigments called Carotenoids are slower to break down than the chlorophyll. 

So instead of looking green they will look yellow, red or orange.


Forming a protective layer

Cells near to the separation area divide and form new cells that both protect and waterproof the area that will be left open to the elements.

Thus reducing the risk of disease and infection.


Detachment

The cells near the separation area produce enzymes that will digest the bit of leaf that is still joined. This causes the separation area to break down and the leaf to fall.

Another way that detachment can happen is by cells near the separation are swelling with water and then bursting so the leaf falls off.

Sometimes the plant not having enough chlorophyll can be a starting point for this process. The sunlight decreases giving less chlorophyll production.


Deciduous or Evergreen

Deciduous plants also lose their leaves to conserve water and this can be seen in a very hot summer. Transpiration (exchange of gases) happens in the leaves that results in loss of water.

Each year these plants have to grow new leaves. Evergreen trees do not have to go through these processes.

There can be more damage to branches and trunks for evergreen trees in the winter storm but they also provide shelter for animals and birds and add a bit of colour to the winter landscape.

Some trees that are deciduous are Maple, Oak, Elm, Beech and Birch. Shrubs include Buddleia, Hydrangea, Magnolia and Acer.


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