Lumber and Its Uses #251944

In addition to the cells whose length is paral lel to the trunk of the tree, wood also contains other layers of cells of a different character whose length is at right angles to the trunk of the tree. These cells occur in thin sheets radiat ing from the bark toward the pith, and form what are called the pith rays or medullary rays of wood. They are best seen on a quartered section, and are what gives the beautiful, flaky appearance to quartered oak and sycamore. The pith rays are less conspicuous in beech, maple, and birch, and are scarcely or not at all visible to the naked eye in the pines and many other woods.