Tree identification by old leaves in winter
In autumn most deciduous trees shed their leaves but some, such as beech and hornbeam retain them throughout the winter and only drop them when the new buds develop. It is not known why some trees retain dead leaves in a process known as marcescence but it only occurs in some species and sometimes only in young trees.
A leaf is the main photosynthetic organ of a tree. This is a process in which carbon dioxide from the air is combined with water in the presence of light to produce sugars and oxygen. The molecule that carries this out is called chlorophyll. It absorbs red and blue wavelengths of light and reflects green so that the leaf appears green to us.
In most trees in autumn shorter days and lower temperatures trigger leaf fall but this is a multi-step controlled shutdown process. Instead of the green leaves just being discarded, the chlorophyll and proteins in the leaf are broken down and essential nutrients, such as nitrogen, are re-adsorbed and stored in the shoots and roots until spring. The brown leaves, containing dead cells and waste products are then shed and form leaf litter which is slowly broken down and nutrients recycled to the soil. In winter you may find old leaves, still on the tree or lying on the ground under the tree. Use this option to identify the tree in winter.
Tree identification by old leaves in winter – photos of the leaves of eleven tree species taken in winter – maples, oaks, beech, aspen, hornbeam and sweet chestnut
For more information on what happens to tree leaves in autumn click HERE