Structure of the Shoot Apical Meristem

Overview

• Meristems: Areas of undifferentiated tissue in plants found in shoots, roots, and flowers.
  • Responsible for plant growth and organ formation.
• Shoot Apical Meristem: Located at the top of the stem.
  • Responsible for the growth of the stem, leaves, and lateral buds.

Zones of the Shoot Apical Meristem

1. Central Zone

   • Located in the center of the meristem.
   • Consists of a small number of large, highly vacuolated cells.
   • Contains stem cells: some are inactive, while others divide to replenish peripheral and rib zones.

2. Peripheral Zone

   • Surrounds the central zone.
   • Contains more and smaller cells compared to the central zone.
   • Cell division here gives rise to leaf primordia.

3. Rib Zone

   • Located further inside and under the central zone.
   • Cell division results in the formation of internal stem tissues.

Layers of the Shoot Apical Meristem

1. Layer 1

   • Outer layer where cell division is anticlinal (cell walls at right angles to the surface).
   • Gives rise to the epidermis.

2. Layer 2

   • Located beneath Layer 1, also with anticlinal cell division.
   • Contributes to internal tissue formation.

3. Layer 3

   • Innermost layer with randomly oriented cell division.
   • Like Layer 2, contributes to internal tissue formation.

Conclusion

• Understanding the structure and function of the shoot apical meristem is critical for grasping how plants grow and develop.

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