Daylight
Photosynthesis
Increase in temperature causes stomata to open. A hydathode is a type of secretary tissue in leaves, usually of Angiosperms , that secretes water through pores in the epidermis or margin of leaves, typically at the tip of a marginal tooth or serration. They probably evolved from modified stomata.
stomata which are tiny spots on the underside of the leaf
Transpiration
They shut because with the stomata open it is too drafty and the plant can't get to sleep.
during the day
Oxygen comes out of the open stomata:)
The leaves would dry out
Stomata are tiny openings on leaves that act as mouths. They open and close to release and take in moisture.
At night, the leaves of C3 plants close their stomata and wait until the sunlight. For CAM plants, this is when the plants open their stomata and allow the carbon dioxide to come in.
Stomata