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.
Daylight
Stomata open in response to environmental factors such as light intensity, CO2 levels, and humidity. Light triggers the production of a hormone called abscisic acid, causing the guard cells around the stomata to swell and open. Conversely, in darkness or when environmental conditions are unfavorable, the stomata close to prevent water loss through transpiration.
When light hits the stomata it activates photosynthetic K+ pumps. These cells pump potassium ions into the guards cell around the stomata. Water is attracted to the potassium ions and thus enters the guards cells. This causes the guard cells to swell, but the rigidity of the one side causes that side to bow inwards, this creates an opening for gases to exchange in the leaf. This opening is the stomata. When water is not present, the stomata will not open.
The guard cells open and close the stomata as needed.
Changes in the osmotic potential of gaurd cells make that stomata open or closed
in the day
To maintain homosigius
no!
the stomata open
the guard cells
Transpiration
They shut because with the stomata open it is too drafty and the plant can't get to sleep.