Everyone knows wood comes from trees, but exactly where in the tree and how did it get inside the tree?
Wood is made up of many elements and woody tissue. These woody tissues are composed of individual fibers of wood and a single fiber of wood is extremely small. When looking at the edge of a torn piece of paper an individual wood fiber should be visible and when looking at a magnified piece of wood’s edge (1,000 x actual size), it will resemble a box of drinking straws. Each wood fiber is hollow just like a straw.
Knowing where wood fibers come from helps in understanding where wood comes from. As explained, wood is made up of tiny fibers. These tiny wood fibers run parallel to each other and are held together by their own coating called lignin; a type of natural adhesive that holds the wood fibers parallel together.
Trees only grow in the warmer parts of a year, in more temperate climates. Bark covers the branches and the trunk of the tree and all wood fibers growth occurring happens at the junction of the bark and the wood called the cambium layer. The cambium allows the tree’s diameter to grow larger and is called the growth layer. Every year a sheath of brand new wood grows; this new wood completely encases the old branches and trunk forming a new layer of wood. The cycle repeats itself every year; this is where rings come from.
During each growing season earlywood, or springwood, forms; this normally weighs less and has a coarser texture than wood that grows toward the end of a growing season. Wood growing late in season is commonly known as latewood or summerwood. Once a tree has reached what is known as a moderate age, the wood in the branches and the wood located near the trunk’s center undergo more changes. Its sapwood, usually lighter in color, changes into heartwood which usually has a darker color. During the tree’s early life the heartwood was actually sapwood. As the tree grew and aged the sapwood inside died and became heartwood. Softwood is more prone to decay than heartwood and most likely when a decayed log is found in the woods it is filled with heartwood; all sapwood would have rotted away.
Even though very young trees are all sapwood, in most species of trees, the band of sapwood surrounding the heartwood is minimal is portion throughout the tree’s trunk. The heartwood these species produce are the reason for rich colors found in wood furniture, like walnut and cherry.