Wood

Wood is the main substance in trees. It is mainly formed by the xylem vessels which carry water up the plant. The two main substances in wood are cellulose and lignin. Wood is used to make buildings and furniture, and also for art. Firewood is a fuel. Paper is made from wood fibres. Wood is a renewable resource although it has become scarcer in recent centuries. Its origin is about 425 million years ago.^[1]

Wood is hard to cut, but it is also strong. A lumberjack is a person who cuts down trees. After a tree falls, the wood in it can be cut into long, straight pieces called lumber. Lumber can then be used to make posts, or put together with nails, screws, or even glue to make wooden frames for other shapes.

Wood comes in many different kinds. Oak, maple (hardwood) and pine and redwood (softwood) are widely used types of wood. Woods are usually divided into softwood (from conifers) and hardwood from flowering plants.^[2]

1. ↑ Labandeira C. 2007. The origin of herbivory on land: Initial patterns of plant tissue consumption by arthropods. Insect Science. 14 (4): 259–275. [1]
2. ↑ Jane F.W. 1970. The structure of wood. 2nd ed, edited by K. Wilson & D.J.B. White. London: Adam & Charles Black. ISBN 9780713609127