meristemin

Meristem is a plant tissue composed of undifferentiated cells that retain the capacity to divide and differentiate into various specialized tissues. Meristematic activity drives plant growth by producing new organs and tissues, enabling plants to grow in length and girth. Meristems are classified by location and developmental role: apical meristems occur at the tips of shoots and roots and drive primary growth; lateral meristems, including the vascular cambium and cork cambium, enable secondary growth and thickening; and intercalary meristems are found in some monocots at leaf bases, contributing to leaf elongation.

A typical apical meristem contains stem cells, or initials, that divide to produce progeny cells. As these daughter cells are displaced away from the apex, they begin to differentiate into the distinct tissue types that form the plant’s organs. Differentiation yields dermal tissue (epidermis), ground tissue (cortex and pith), and vascular tissue (xylem and phloem). Meristem activity is tightly regulated by genetic networks and plant hormones, especially auxins and cytokinins, which influence the balance between cell division and differentiation and coordinate organ formation.

In vascular plants, meristems underpin both above-ground and underground development and are central to growth, regeneration, and tissue replacement. They also have practical importance in agriculture and horticulture; meristem culture is used to clonally propagate plants and produce virus-free material.

Overall, meristems represent the plant’s active growth tissue, enabling continuous development throughout the life cycle.