Search results
Results from the WOW.Com Content Network
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.
Pneumatodes are considered as a special type of cyclocytic stomata. The entire structure may rise above the adjacent epidermis. The pneumatodes may function as double structures for gas exchange and liquid water elimination . [6] Leafless orchids with photosynthetic roots rely on the gas exchange through pneumatodes for photosynthesis.
Plant gas exchange occurs mostly through the leaves. Gas exchange between a leaf and the atmosphere occurs simultaneously through two pathways: 1) epidermal cells and cuticular waxes (usually referred as 'cuticle') which are always present at each leaf surface, and 2) stomata, which typically control the majority of the exchange. [37]
"Lenticel" seems to be the most appropriate term to describe both structures mentioned in light of their similar function in gas exchange. Pome lenticels can be derived from no longer functioning stomata, epidermal breaks from the removal of trichomes, and other epidermal breaks that usually occur in the early development of young
SV channels have been shown to function as cation channels that are permeable to Ca 2+ ions, [35] but their exact functions are not yet known in plants. [39] Guard cells control gas exchange and ion exchange through opening and closing. K+ is one ion that flows both into and out of the cell, causing a positive charge to develop.
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.
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).
Gas exchange with the atmosphere is controlled by stomata, which can open and close to control water loss, and diffusion of carbon dioxide to the chloroplasts takes place in intercellular spaces between chlorenchyma cells in the stem or in the mesophyll tissue of the leaf. [1]