What is wood?

Have you ever looked at your wooden furniture and wondered where did the wood come from? The story of what wood is and how it turns into furniture is something that many people take for granted, but is quite fascinating.  

Credit: Mariya Chorna

Wood comes from harvested trees. Different trees produce different kinds of wood. We choose a particular kind of wood due to its material properties and beauty.

Credit: Savatree

Looking closer at the structure of wood, we can see that wood has several layers within it. Starting from the outermost layer which is visible, that is known as the bark. The bark serves as protection against the external environment. Below the bark, there is a living layer known as the sapwood. The sapwood is filled with tubes called xylem that transport nutrients and water along the trunk of tree from the roots to the leaves.

The annual growth rings you find in wood is formed by the cambium. It is a thin layer at the outer edge of the sapwood that is actively growing outwards.

Below the sapwood layer, we can find the harder and darker part of the wood known as the heartwood. The xylem tubes are normally not active as they have been blocked by resin or gum.

The lines you see in furniture that are running in parallel is known as the grain. The grain are due to the xylem tubes. Sometimes, you might see small whorls or ovals in the wood and these are called knots.

We will look at where wood comes from in the next article as different parts of the world contribute different types of wood. There are around 500 kinds of species that are used regularly for construction, furniture, tools and art.