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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.
When the stomata are open, water is lost by evaporation and must be replaced via the transpiration stream, with water taken up by the roots. Plants must balance the amount of CO 2 absorbed from the air with the water loss through the stomatal pores, and this is achieved by both active and passive control of guard cell turgor pressure and ...
ABA then translocates to the leaves, where it rapidly alters the osmotic potential of stomatal guard cells, causing them to shrink and stomata to close. The ABA-induced stomatal closure reduces transpiration (evaporation of water out of the stomata), thus preventing further water loss from the leaves in times of low water availability. A close ...
The stomata complex regulates the exchange of gases and water vapor between the outside air and the interior of the leaf. Typically, the stomata are more numerous over the abaxial (lower) epidermis of the leaf than the (adaxial) upper epidermis. An exception is floating leaves where most or all stomata are on the upper surface.
Number of stomata: More stomata will provide more pores for transpiration. Size of the leaf: A leaf with a bigger surface area will transpire faster than a leaf with a smaller surface area. Presence of plant cuticle: A waxy cuticle is relatively impermeable to water and water vapor and reduces evaporation from the plant surface except via the ...
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 ...
It was thought that this avoidance serves a protective function to avoid damage from intense light, [9] however an alternate study argues that the avoidance response is primarily to increase light penetration into deeper mesophyll layers in high light conditions. [10] Phototropins may also be important for the opening of stomata. [11]
They also separate stomata apart from each other as stomata have at least one pavement cell between each other. [4] They do not have a regular shape. Rather, their irregular shapes help them to interlock with each other like puzzle pieces to form a sturdy layer. [5]