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Guard cells are cells surrounding each stoma. They help to regulate the rate of transpiration by opening and closing the stomata. Light is the main trigger for the opening or closing. [citation needed] Each guard cell has a relatively thick and thinner cuticle [clarification needed] on the pore-side and a thin one opposite it. As water enters ...
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 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) Guard cells are the only epidermal cells that can make sugar.
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]
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.
In plants, the substomatal cavity is the cavity located immediately proximal to the stoma. It acts as a diffusion chamber connected with intercellular air spaces and allows rapid diffusion of carbon dioxide and other gases (such as plant pheromones ) in and out of plant cells .
Mesophytes do not have any special internal structure. Epidermis is single layered usually with obvious stomata. Opening or closing of stomata is related to water availability. In sufficient supply of water stromata remain open while in limited supply of water stomata are closed to prevent excessive transpiration leading to wilting. [citation ...
Guard cell – one of the paired epidermal cells that control the opening and closing of a stoma in plant tissue. Heartwood – the older, nonliving central wood of a tree or woody plant, usually darker and harder than the younger sapwood. Also called duramen. Herbaceous – non-woody and dying to the ground at the end of the growing season.