We have a definite growth pattern and growth stops at certain stage or age. But plant growth is indefinite. All the time, the plant body possess certain cells that are actively dividing and adding new cells thereby effecting growth. These cells are called as meristem.
Definition: Meristems are actively dividing immature cells that form new cells by cell division.
Characteristics of Meristamatic cells
1. Isodiametric, spherical, oval or polygonal cells
2. Thin walled as these cells are in continuous division
3. Large nucleus
4. Dense protoplasm
5. Less number of vacuoles
6. Arranged without intercellular spaces
7. Always in active metabolic state
The above characters are typical of cells with high metabolic activity.
Plant Meristem: Definition and Classification based on origin, position and plane of division