Phytohormone is a biologically active substance produced in plants and regulates their growth, development and physiological processes. Unlike animal hormones, phytohormones can act not only at the site of their synthesis, but also move around the plant, affecting distant organs.
Major phytohormone groups include auxins, cytokinins, gibberellins, abscisic acid, and ethylene. They control processes such as cell division, tissue stretching, flowering, aging, fruit formation, and response to stressful conditions.