Abnormal growth rings formed in response to leaning or crooked stems. In hardwoods it is termed "tension wood" and in softwoods "compression wood".
Reaction wood is wood formed in trees where the main stem is tipped from the vertical. It also often forms following the deflection of a lateral stem (branch) from its normal orientation. Reaction wood formed in hardwoods differs from that formed in softwoods. In softwoods, reaction wood is called compression wood; reaction wood in hardwoods is called tension wood. Both compression wood and tension wood are lower in quality than normal mature wood. As with juvenile wood, reaction wood is viewed as least desirable in lumber and in other products in which wood is used in solid form.
Distorted wood formed in leaning trunks and branches of trees. Reaction wood dries unpredictably, often twisting and cracking.
Abnormal wood tissue that was formed in a leaning tree. Reaction wood is very unstable and prone to warping and cupping when sawn into lumber.
Related Article Abnormal wood formed in a leaning tree, often characterized by a dense hard brittle grain and propensity to react irregularly to seasonal moisture changes. In hardwood trees, it forms on the upper side of the lean and is called tension wood. In softwood trees it forms on the lower side of the lean and is called compression wood.
Wood with more or less distinctive anatomical characters, formed typically in parts of leaning or crooked stems and in branches; in hardwoods this consists of tension wood and in softwoods of compression wood.
Reaction wood is formed in response to mechanical stress, and helps to position newly formed parts of the plant in an optimal position. Reaction wood forms when a woody plant part is subjected to mechanical stress. This stress may be the result of wind exposure, excess of snow, soil movement, etc.