Each floral meristem produces primordia which form the various floral organ, such as sepals, petals, stamens and carpels. All shoot growth occurs through the production of lateral organs and secondary meristems by primordia, and this accounts for the characteristic branched appearance of plants. The activity of meristems is often iterative. For example, a vegetative meristem will produce modular units each consisting of a leaf, bud, and internode. Each unit is called a phytomer.
Meristems are self-organising.
For example, meristems regenerate after bisection. Vegetative meristems are indeterminate, and in some species are capable of growth for thousands of years. In other words, some mechanism must be in place to maintain the size of the meristem. Architecture of the Arabidopsis shoot meristem. The central zone contains a core of stem cells, while the peripheral zone is the site of production of lateral organ primordia and the rib zone gives rise to differentiated cells of the growing stem.