Why do few plants adapted to a dry environment open their stomata only at night?
Throughout the day in dry habitats the guard cells become the stomata close and flaccid; concurrently carbon dioxide is disallowed to pass to participate in diurnal photosynthesis. Few plants from dry regions solve this problem through the method of nocturnal carbon dioxide fixation. At night, as water loss by transpiration is lower, the stomata open, carbon dioxide enters and it is stored within the parenchymal tissues. Throughout the day the stored gas is mobilized to be used in photosynthesis