Wood has evolved over millions of years to serve three main functions for itself:
- Conduction of water from the roots to the leaves
- Mechanical support of the plant body
- Storage of biochemicals
As a complex biological structure, a composite material of many chemical and cell types acting together to serve the needs of a living plant, wood is a versatile material suited to many uses.
As Alex Wiedenhoeft writes in Chapter Three of the Wood Handbook, there is no property of wood – physical, mechanical, chemical, biological, or technological-that is not fundamentally derived from the fact that wood is formed to meet the needs of the living tree. Wiedenhoeft is a research botanist at FPL, working within the Engineering Properties of Wood, Wood Based Materials and Structures group and affiliated with the Center for Wood Anatomy Research.
The three primary functions of trees have influenced the evolution of approximately 20,000 different species of woody plants, each with unique properties, uses, and capabilities, in both plant and human contexts. Chapter Three categorizes the biological structure of wood at decreasing scales, from the whole tree and tree types, to axial and radial systems, vascular cambium, growth rings, and cellular differences. Wiedenhoeft also examines the appearance of wood as sawn lumber in terms of color and luster, grain and textures, slope of grain, knots, and decorative features. Chapter Three wraps up with a section on the importance of wood identification from a scientific perspective.