A growth layer in secondary xylem seen in a cross section of a woody stem or branch.
A layer of calcareous material or other substance deposited in a single period of growth of an animal, as in an otolith or a turtle scute.
A layer of wood formed in a plant during a single period of growth. Growth rings are visible as concentric circles of varying width when a tree is cut crosswise. They represent layers of cells produced by vascular cambium. &diamf3; Most growth rings reflect a full year's growth and are called annual rings. But abrupt changes in the environment, especially in the availability of water, can cause a plant to produce more than one growth ring in a year.
A similar layer in a part of an animal marking a period of growth, such as an annulus in a fish scale.