the cumulative layers of cells produced during a single growing season and characteristically containing earlywood and latewood cells of differing morphology —synonym annual ring —note growth rings commonly occur annually in trees grown in temperate regions having distinct growing seasons and a period of dormancy; in tropical regions having more than one active growth in one year, there is no clear demarcation indicating the beginning or the end of successive growth increments —see discontinuous ring, false ring This definition last updated 10/27/2008