meristem

noun

(Gr. meristês: dividing) The growing regions of a plan, made of a plant tissue consisting of actively dividing cells that give rise to cells that differentiate into new tissues of the plant, to produce the definitive tissues and organs. The most important meristems are those occurring at the tip of the shoot and root (see apical meristem) and the lateral meristems in the older parts of the plant (see cambium, cork cambium).