92; also p.

126, appendix.] Since the late wood of a growth ring is usually darker in color than the early wood, this fact may be used in judging the density, and therefore the hardness and strength of the material.

This is particularly the case with coniferous woods.
In ring-porous woods the vessels of the early wood not infrequently appear on a finished surface as darker than the denser late wood, though on cross sections of heartwood the reverse is commonly true.

Except in the manner just stated the color of wood is no indication of strength.
Abnormal discoloration of wood often denotes a diseased condition, indicating unsoundness.

The black check in western hemlock is the result of insect attacks.[29] The reddish-brown streaks so common in hickory and certain other woods are mostly the result of injury by birds.[30] The discoloration is merely an indication of an injury, and in all probability does not of itself affect the properties of the wood.