FNR 43 1977
forestry & natural resources
ENVIRONMENTAL FORESTRY 
How to Identity Some Common Indiana Woods
by W. L. Fix, Extension Forester
Woods differ in strength, hardness, color, odor, weight and other properties, as well as their structure. These differences can be used in their identification.
To identify an unknown wood, cut a smooth surface on the end or cross section of the sample with a sharp knife. Here you will see the annual rings just as they appear on a stump in the woods. Using a hand lens, check to see if openings, called pores can be seen within the annual rings. The pores, easily seen in oaks, ash, and hickory, are tubes which carry water and nutrients from the tree roots to the leaves.
In some hardwood (broadleaf) trees, the pores may be larger on one side of the annual ring. The area containing the larger pores, which is always on the side of the annual ring toward the center of the tree, is called springwood and grew during the early spring season. The area of smaller pores, along the outside of the annual ring, grew during the summer and so is called summerwood. Thus, an annual ring is actually made up of a band of springwood and a band of summerwood.
Woods having large pores in the springwood and small pores in the summerwood are called ring-porous woods. These include the oaks, elm, ash, and others.
Woods having springwood and summerwood pores about the same size are called diffuse-porous. Among others, these include sycamore, tuliptree, beech and the maples. A few other woods, such as walnut and cherry, have a gradual change from larger springwood pores to smaller summer-wood pores. These are often called semi-ring-porous woods. The first step, then, in wood identification of the hardwoods is to separate the woods into one of these groups.
In a few species the large springwood pores may appear under the hand lens to be closed, or filled. White oak is a member of this group (see sketch).
In some species, groups of cells will be found in the summerwood arranged in various patterns. These may be roughly triangular (as in white oak), in short lines (as in red oak), wavy horizontal bars (as in red elm), in small isolated clusters, or may appear as more or less continuous fine lines (as in hickory). These serve as additional aids to identification of many species.
Wood Rays
Look again at the cross section of white or red oak. You will see ribbon-like streaks or lines running across the annual rings from the center of the tree to the outside. These are rows of cells which give oak some of its figure and are known as wood rays. Rays serve to transport substance laterally within the tree, for food storage and vary in size among species. In cottonwood, for example, they are not usually visible to the naked eye. Rays also appear more numerous in some kinds of wood than in others. Therefore, both the size and number of rays are used in wood identification. Rays are large and easily seen in oak, beech and sycamore. Rays in tuliptree, sweetgum and basswood appear much less distinct to the naked eye. The rays may also vary in size in any one species. White oak, for example, has some wide and very conspicuous rays and others, in between, that are narrow and indistinct. In black walnut the rays are quite uniform in width and indistinct without a hand lens.
Color, Hardness, and Figure
Color, degree of hardness, and figure are also used to assist in identification of woods. Sapwood, the outer living portion of the stem, is usually lighter in color than the Heartwood, the dead inner wood near the center of a tree. Hardness may be tested by a finger nail. Soft woods, such as basswood and cottonwood, are easily indented. Hard woods, such
PURDUE UNIVERSITY • COOPERATIVE EXTENSION SERVICE • WEST LAFAYETTE, INDIANA 47907