Winter twig challenge

Why do some trees lose their leaves?

Leaves use sunlight along with water to create food for the plant (photosynthesis).

In the UK in winter the days are too short and there is little sunlight for this process to happen effectively; plus freezing weather stops the supply of water to the leaf.

• Leaves of deciduous trees are also quite delicate parts of the tree prone to frost damage, so deciduous trees choose to shed their leaves and remain dormant until spring.
  
  
• Evergreen trees do keep most of their leaves; this enables some slow photosynthesis to happen at times during the winter as long as they get enough water.
  
  
• Evergreen leaves are designed to be much more resistant to cold and water loss. Some, like pine and fir trees, have long thin needles. Others, like holly, have broad leaves with tough, waxy surfaces.

• But even evergreen leaves are prone to damage from weather or insects, and will need replacing over time. The tree does this gradually in intervals so the trees always retain enough leaves to continue to function.

 How good are you at identifying winter twigs?