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noun, plural: stomates

(botany) A tiny pore on the surface of a leaf or herbaceous stem surrounded by a pair of guard cells that regulate its opening and closure, and serves as the site for gas exchange.


The stomates are actually the pores created by the swelling of guard cells to allow CO2 to enter into the leaf, which is a necessary reactant of photosynthesis. The water vapor and O2 are also allowed to escape via the pore. In order to form the pore, osmotic pressure draws water to increase the cells volume; this in turn causes the guard cells to bow apart from each other because the inner wall of the pore is more rigid than the wall on the oppostie side of the cell.

Stomates are present in all terrestrial plants (in sporophyte phase), except for the liverworts. Dicots usually have more on the lower epidermis than the upper epidermis whereas monocots usually have the same number on both sides. Plants whose leaves float in water have stomates only on the upper epidermis whereas plants whose leaves are completely submerged may lack a stomate entirely.

Synonym: stoma (botany).

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Regulating Stomata...question

... guard cell at a greater rate than it goes out, thus producing an increase in turgar pressure, thus swelling of the guard cells and opening of the stomate. Doc44 Check out why a saturated NaCl solution will have a potentially higher osmotic potential than a saturated glucose solution. Keep your ...

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by Doc44
Mon May 15, 2006 12:49 am
Forum: Botany Discussion
Topic: Regulating Stomata...question
Replies: 6
Views: 2980

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