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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 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 ...
Some liverworts, such as Marchantia, have a cuticle, and the sporophytes of mosses have both cuticles and stomata, which were important in the evolution of land plants. [ 3 ] All land plants have a life cycle with an alternation of generations between a diploid sporophyte and a haploid gametophyte , but in all non-vascular land plants, the ...
In anatomy, a stoma (pl.: stomata / ˈ s t oʊ m ə t ə / or stomas) is any opening in the body. For example, a mouth , a nose , and an anus are natural stomata. Any hollow organ can be manipulated into an artificial stoma as necessary.
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.
As the epidermis of the plant is covered with water barriers such as lignin and waxy cuticles, the night opening of the stomata is the main channel for water movement for xerophytes in arid conditions. [12] Even when water is not scarce, the xerophytes A. Americana and pineapple plant are found to utilise water more efficiently than mesophytes ...
An important conclusion from these phylogenies is that the ancestral stomata appear to have been lost in the liverwort lineage. [39] [36] Among the earliest fossils believed to be liverworts are compression fossils of Pallaviciniites from the Upper Devonian of New York. [42] These fossils resemble modern species in the Metzgeriales. [43]