Plants can minimize water loss by closing stomata, but this must be balanced by the need to take in atmospheric CO2 for sugar production. (joshuatreegenome.org)
Plant biologists know that stomata open when exposed to light and close in darkness, but the dynamics of this opening and closing have been little studied because there hasn't been a good way to directly measure them in real time. (sciencedaily.com)
There is evidence plant stomata decrease in number and size with increased CO2. (judithcurry.com)