Q: My husband was splitting wood this past week. One section was very curved. When he split that section, it had waves in it. It is very beautiful. We decided it had grown with an excessive weight on one side that forced its growth in that direction.
A: Certified arborist Art Morris (Bartlett Tree Experts) says:
“The waviness of this wood is likely caused by the growth of “reaction wood.”
“Trees often grow with a lean or bow, and large lateral limbs may extend dozens of feet from the trunk. To help support a lean or the weight of a large limb, trees form reaction wood. In hardwood trees extra layers of wood fiber are added to the top side of the lean or limb to provide tension to hold up the weight of wood and foliage.
“In pines, this extra wood is added below to the limb or trunk to form compression wood for the same purpose. This is why the cross section of large heavy limbs is often oval shaped, rather than perfectly circular, and explains the wavy grain pattern in this piece of wood.
“The interesting grain patterns and dense wood formed by reaction wood are prized by wood carvers, but often cause problems for the lumber industry.”
see Figure in Wood