The epidermis of plant leaves, stems, and other organs contains specialized cells that play important roles in regulating processes like transpiration and gas exchange. One such group of specialized cells are the subsidiary cells (also known as accessory cells), which surround the guard cells in the stomata.
Key Points:
Subsidiary Cells: These are specialized epidermal cells that are found surrounding the guard cells in the stomata.
Function: Subsidiary cells support the guard cells by helping to control the opening and closing of the stomatal pore. They are essential for regulating the exchange of gases (like CO₂ and O₂) and water vapor between the plant and its environment.
Structure: These cells are often more elongated or shaped differently compared to the surrounding epidermal cells. In some plant species, subsidiary cells may also help to store ions and contribute to the osmotic regulation of the guard cells.
Role in Stomatal Function: Subsidiary cells work in coordination with the guard cells to ensure that stomata open and close at the appropriate times, thus helping to maintain homeostasis within the plant.
Conclusion:
In summary, subsidiary or accessory cells are vital to the functioning of guard cells and help in regulating stomatal movement for efficient gas exchange and water balance in plants.
The epidermal tissue system forms the outer-most covering of the whole plant body and comprises epidermal cells, stomata, and the epidermal appendages – the trichomes and hairs. The epidermis is the outermost layer of the primary plant body. It is made up of elongated, compactly arranged cells, which form a continuous layer. The epidermis is usually single-layered.
Ground Tissue System:
All tissues except the epidermis and vascular bundles constitute the ground tissue. It consists of simple tissues such as parenchyma, collenchyma, and sclerenchyma. Parenchymatous cells are usually present in the cortex, pericycle, pith, and medullary rays, in the primary stems and roots. In leaves, the ground tissue consists of thin-walled chloroplast-containing cells and is called mesophyll.
Vascular Tissue System:
The vascular system consists of complex tissues, the phloem, and the xylem. The xylem and phloem together constitute vascular bundles. In dicotyledonous stems, cambium is present between phloem and xylem. Such vascular bundles because of the presence of cambium possess the ability to form secondary xylem and phloem tissues and hence are called open vascular bundles. In the monocotyledons, the vascular bundles have no cambium present in them. Hence, since they do not form secondary tissues they are referred to as closed.
