During droughts, many plants close their stomata by directing more water into guard cells that circle the pores.
12.
These guard cells are in turn surrounded by subsidiary cells which provide a supporting role for the guard cells.
13.
These guard cells are in turn surrounded by subsidiary cells which provide a supporting role for the guard cells.
14.
Finally, the guard cells of the latter average 49 micrometers, slightly larger than the 46 micrometers of the former.
15.
However, this is now thought to result from the loss of the wall separating paired guard cells during fossilisation.
16.
The stomata are haplocheilic, monocyclic or dicyclic, usually depressed, with the guard cells occurring in the lowermost part of the stoma.
17.
At night, the sugar is used up and water leaves the guard cells, so they become flaccid and the stomatal pore closes.
18.
"' Guard cells "'are specialized cells in the epidermis of leaves, stems and other organs that are used to control gas exchange.
19.
This electrical depolarization of guard cells leads to activation of the outward potassium channels and the release of potassium through these channels.
20.
The term is also used collectively to refer to an entire stomatal complex, both the pore itself and its accompanying guard cells.
