Growth rings of Pinus taeda

Growth rings can be seen in a horizontal cross section cut through the trunk of a tree. Visible rings result from the change in growth speed through the seasons of the year, thus one ring usually marks the passage of one year in the life of the tree. The rings are more visible in temperate zones, where the seasons differ more markedly.

Growth rings are the basis for the historical dating science of dendrochronology.

Growth rings are responsible for the grain and knots visible in wood.