ABA (abscisic acid) is called a stress hormone.
(a) How does this hormone overcome stress conditions?
(b) From where does this hormone get released in leaves?
(a) ABA helps when the water available is scarce and communicates with the stomata. This causes the stomata to close, thus stopping the process of transpiration and saving the excess loss of water and conserving it instead. This helps regulate stress situations.
(b) The stem apex releases ABA to travel to the leaves.