What forms the stomatal apparatus?

Stomata are microscopic structures present in the epidermis of leaves that control transpiration and gaseous exchange. Together with associated cells, they form the stomatal apparatus, which has three main parts:

1. Stomatal Pore
   • A small opening through which carbon dioxide enters for photosynthesis and oxygen is released.
   • It also allows the loss of water vapor during transpiration.
2. Guard Cells
   • Each stoma is surrounded by two bean-shaped guard cells (dumb-bell shaped in grasses).
   • Their inner walls are thick and outer walls are thin, enabling them to regulate the opening and closing of the stomatal pore.
   • Radially arranged microfibrils in guard cells help in stomatal movement.
3. Subsidiary Cells
   • Specialized epidermal cells located around guard cells.
   • They support guard cells by aiding in their function and adjusting their shape and size.