Meristematic tissues are a type of tissue found in plants that contain undifferentiated cells capable of cell division/30%3A_Plant_Form_and_Physiology/30.11%3A_Plant_Development_-Meristems). These cells can develop into all the other tissues and organs that occur in plants. Differentiated plant cells generally cannot divide or produce cells of a different type. Meristematic cells are undifferentiated or incompletely differentiated, totipotent, and capable of continued cell division. Division of meristematic cells provides new cells for expansion and differentiation of tissues and the initiation of new organs, providing the basic structure of the plant body. The cells are small, with small vacuoles or none, and protoplasm filling the cell completely. There are three types of meristematic tissues: apical (at the tips), intercalary or basal (in the middle), and lateral (at the sides) /30%3A_Plant_Form_and_Physiology/30.11%3A_Plant_Development-Meristems). At the meristem summit, there is a small group of slowly dividing cells, which is commonly called the central zone. Cells of this zone have a stem cell function and are essential for meristem maintenance. The proliferation and growth rates at the meristem summit usually differ considerably from those at the periphery. There are two types of apical meristem tissue: shoot apical meristem (SAM), which gives rise to organs like the leaves and flowers, and root apical meristem (RAM), which provides the meristematic cells for future root growth/30%3A_Plant_Form_and_Physiology/30.11%3A_Plant_Development-_Meristems). SAM and RAM cells divide rapidly and are considered indeterminate, in that they do not possess a pre-determined fate.