Organization of tension wood fibers in Poplar stem

Tension wood is a defect in hardwood trees. It causes excessive shrinkage, splitting, warping and wooliness in lumber and veneer. The element involved in these defects is the abnormal gelatinous layer developing in the libriform fibers of many hardwood species. This unusual cell wall layer is often deposited inside the secondary wall as a response to the lack of perpendicularity between the tree and the gravitational pull