Variation in structure of any kind of wood may result from
relatively minor differences in the woody tissue laid down in
different parts of the tree, or in similar parts of different
trees. Seemingly minor changes in cell wall thickness, fiber lengths,
cell diameters, celluloselignin ratios, or percentages of cell
types cause marked differences in physical properties of the wood.
Since wood is ultimately judged on its quality, i.e., on its suitability
for a particular use, the assessment of the effects that
anatomical differences may have on wood properties becomes
important.