SOFTWOODS and HARDWOODS

SOFTWOODS and HARDWOODS

In the plant kingdom, hardwoods are angiosperms (flowering plants – broad leaved plants) and softwoods are gymnosperms (cone-bearing plants usually with needle like leaves).

Softwoods4 (make long fibred pulp) have a simple wood structure where most of the wood consist of tracheids – long narrow cells up to 7 mm long. Tracheids functions include – conducting water and nutrients up from the roots, supporting the tree and providing physical support and strength. In coniferous or softwood species as a result the material is much more uniform in structure than that of most hardwoods. There are no vessels ("pores") in coniferous wood such as one sees so prominently in oak and ash, for example.

Hardwoods (make short fibred pulp) have a more complex wood structure. Vessels are long hollow pipes consisting of wide short cells stacked one above the other. These hollow vessels carry water and nutrients up from the roots. Fibres are the strength giving cells. They are short (about 1 mm long and usually thick walls). Their only function is to support the tree. They are the most numerous cells.

In discussing such woods, it is customary to divide them into two large classes, ringporous and diffuse-porous. The main physical characteristic of wood fibres is their strong tension that is created both by its natural strength, and the way the fibres are embedded in a matrix that very effectively resists compression. Wood plays an important supporting role in a living tree – it enables all woody plants a strong structure on which they can grow and reach more sunlight than surrounding plant life, to elevate their fruit from the easy reach of animals and off course, it conveys the nutrients and water between roots and canopy.

4 Source Qld Forestry ForEd Project 1982-1985.