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In botany, a stoma (pl.: stomata, from Greek στόμα, "mouth"), also called a stomate (pl.: stomates), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange between the internal air spaces of the leaf and the atmosphere.
Photosynthesis depends on the diffusion of carbon dioxide (CO 2) from the air through the stomata into the mesophyll tissues. Oxygen (O 2), produced as a byproduct of photosynthesis, exits the plant via the stomata. When the stomata are open, water is lost by evaporation and must be replaced via the transpiration stream, with water taken up by ...
The leaf and stem epidermis is covered with pores called stomata (sing; stoma), part of a stoma complex consisting of a pore surrounded on each side by chloroplast-containing guard cells, and two to four subsidiary cells that lack chloroplasts. The stomata complex regulates the exchange of gases and water vapor between the outside air and the ...
The stomata sit in small pits within the curls of the structure, which makes them less likely to open and lose water. The folded leaves have hairs on the inside to slow or stop air movement, much like many other xerophytes (though these are typically found on the outside of the plant,in marram grass they are also within the leaf as this has now ...
More leaves (or spines, or other photosynthesizing organs) means a bigger surface area and more stomata for gaseous exchange. This will result in greater water loss. 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 ...
The movement of water out of the leaf stomata sets up transpiration pull or tension in the water column in the xylem vessels or tracheids. The pull is the result of water surface tension within the cell walls of the mesophyll cells, from the surfaces of which evaporation takes place when the stomata are open.
To do so two partially isolated compartments differentiate within leaves, the mesophyll and the bundle sheath. Instead of direct fixation by RuBisCO, CO 2 is initially incorporated into a four-carbon organic acid (either malate or aspartate) in the mesophyll. The organic acids then diffuse through plasmodesmata into the bundle sheath cells.
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]