Not all trees shed their leaves in winter. Some have special defenses which enable them to stand up to snow and ice. These trees are known as evergreens. One of the most common examples is the fir tree, better known as the Christmas tree.

Fir trees look extremely pretty when they are covered in snow, but the snow does not remain on them for long. The branches of the fir tree are made to bend under a weight and when the snow becomes too heavy the branch sags downwards and the snow slides off. This is how the fir tree protects itself against the weight of snow that falls in the mountains and which would otherwise crush the tree.

Conifers are so well protected from the rigours of winter that they can wear their beautiful green foliage when the weather is bitterly cold. The leaves of conifers are as thin as needles and covered in a special substance which protects them from the frost. This substance also prevents excessive evaporation of the moisture from the leaf which would cause the leaf to wither and drop off.

When the branch of a conifer is broken the wound is soon covered with a waterproof resin which heals the scar. This resin, which has an aromatic smell, is produced in large quantities by conifers.

Leaving aside food plants, conifers include some of our most useful plants. More than three quarters of commercial timber is obtained from them and a large amount of coniferous wood is used as pulp in the manufacture of paper.