Don't worry: it's not the sign of a diseased tree. There's a simple scientific function that explains why some trees hold onto their leaves in winter, but it doesn't address the deeper purpose of ...

the water in even the most cold-hardy tree will freeze. Broadleaf, deciduous trees lose their leaves in the winter to reduce water loss inside the trunk and branches. Most needle-leaved trees, known ...

It then stores them for winter in its roots. As the tree does this, the green chlorophyll is removed, which reveals hidden colours in the leaves. The first colours to appear are yellow ...

During the spring and summer the leaves have served as factories where most of the foods necessary for the tree's growth are manufactured. This food-making process takes place in the leaf in numerous ...

Extensive infestations can result in the tree losing so many leaves that it can’t photosynthesize ... with a thick horizontal stripe against their lace-patterned wings, where they get the ...