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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.
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 ...
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 ...
Stomatal conductance, usually measured in mmol m −2 s −1 by a porometer, estimates the rate of gas exchange (i.e., carbon dioxide uptake) and transpiration (i.e., water loss as water vapor) through the leaf stomata as determined by the degree of stomatal aperture (and therefore the physical resistances to the movement of gases between the air and the interior of the leaf).
The leaf is an integral part of the stem system, and most leaves are flattened and have distinct upper and lower surfaces that differ in color, hairiness, the number of stomata (pores that intake and output gases), the amount and structure of epicuticular wax, and other features.
The most important benefit of CAM to the plant is the ability to leave most leaf stomata closed during the day. [9] Plants employing CAM are most common in arid environments, where water is scarce. Being able to keep stomata closed during the hottest and driest part of the day reduces the loss of water through evapotranspiration , allowing such ...
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]
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 ...