Larch wood is very valuable, and is used for many purposes. It is very tough, and does not rot in water. Joiners tell us there are fewer knots in planks of Larch than in those of either Silver Fir or Spruce. Wood knots are scars which occur where a dead branch has fallen from the tree, and builders complain that when the tree is sawn into planks, the knots shrink and fall out, leaving a round hole. This reduces the value of the wood; but in the Larch planks the knots are said not to come away from the surrounding wood. PLATE XXI THE SPRUCE FIR Although the Scotch Pine is sometimes called the Scotch Fir, the latter name is generally admitted to be a mistake. It was given long ago by people who had not seen the real Fir trees, and who did not know how different they are from the Pines. It is several hundred years since the Spruce Fir was brought to this country, but it is not one of our native trees, like the Scotch Pine, the Yew, and the Juniper. The Spruce (1) is one of our tallest trees; it loves to grow on ground many thousand feet above the level of the sea; and in Switzerland and Norway there are great forests of these slender, soldier-like trees, clothing the sides of the giant snow mountains. With us it does not grow so abundantly, but you will find many Spruce Firs mingling with the Scotch Pine in the large woods of our Scotch Highlands. The Spruce Fir has a very straggling root which does not penetrate far into the ground; it creeps along close under the surface, and intertwines itself with any other tree roots in the neighbourhood. This does not give it a very firm hold, and after great gales you sometimes find a broad path opened in the Fir woods, which has been made by the Spruce trees falling in the track of the storm. [Illustration: PLATE XXI THE SPRUCE FIR 1. Spruce Fir Tree 2. Leaf Spray 3. Stamen Flowers 4. Seed Flower 5. Cone 6. Seed Scale 7. Growth caused by an Insect] It is a very straight tree, with a smooth scaly bark of a reddish brown colour; from each side of the trunk slender branches grow straight out like the spokes of a wheel; but each branch rises a little way above the last as the steps rise in a ladder. These branches are very slender, and at first they sweep downwards in graceful curves; but at the tips they all turn upward, so that the points look toward the sky. The branches get smaller and smaller as the tree grows higher, which gives it the appearance of a pyramid, and at the very top there stands a single upright branch like a spear. This spear-like tip is one of the distinctive features of the Spruce Fir.