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This depolarization triggers potassium plus ions in the cell to leave the cell due to the unbalance in the membrane potential. This sudden change in ion concentrations causes the guard cell to shrink which causes the stomata to close which in turn decreases the amount of water lost. All this is a chain reaction according to his research.
Stoma in a tomato leaf shown via colorized scanning electron microscope image A stoma in horizontal cross section The underside of a leaf. In this species (Tradescantia zebrina) the guard cells of the stomata are green because they contain chlorophyll while the epidermal cells are chlorophyll-free and contain red pigments.
The guard cells differ from the epidermal cells in the following aspects: The guard cells are bean-shaped in surface view, while the epidermal cells are irregular in shape; The guard cells contain chloroplasts, so they can manufacture food by photosynthesis (The epidermal cells of terrestrial plants do not contain chloroplasts)
As the leaf grows, the pavement cells will also grow, divide, and synthesize new vacuoles, plasma membrane parts, and cell wall components. A thick external cell wall influences the direction of growth by impeding expansion towards the outside of the cell and instead promote expansion parallel to the epidermis layer. [7]
The epidermal cells are the most numerous, largest, and least specialized and form the majority of the epidermis. They are typically more elongated in the leaves of monocots than in those of dicots. Chloroplasts are generally absent in epidermal cells, the exception being the guard cells of the stomata. The stomatal pores perforate the ...
Idioblast cells are believed to be the precursors for guard cells, trichiomes, gland cells, and subsidiary cells of stomata. [8] The uneven division of idioblasts causes extreme differentiation in their daughter cells, with many daughter cells having different functions from their parent cell.
The plant cuticle is one of a series of innovations, together with stomata, xylem and phloem and intercellular spaces in stem and later leaf mesophyll tissue, that plants evolved more than 450 million years ago during the transition between life in water and life on land. [11]
The outside of the stem is covered with an epidermis, which is covered by a waterproof cuticle. The epidermis also may contain stomata for gas exchange and multicellular stem hairs called trichomes. A cortex consisting of hypodermis (collenchyma cells) and endodermis (starch containing cells) is present above the pericycle and vascular bundles.