What do meristematic tissues consist of?

Meristematic tissues are characterised according to their position: apical meristem (at the tips of the stem and roots), lateral meristem (vascular and cork cambium), and intercalary meristem (at the basal portion of internodes in Graminae members).
Primary growth is controlled by the apical meristem. In bamboo plants, for example, the lateral meristem is responsible for secondary development, whereas the intercalary meristem is responsible for internode elongation.