Plant hormones (auxins, gibberellins, cytokinins, ethylene, abscisic acid) act as chemical messengers that control many plant growth and developmental processes. They are produced in one part of the plant and transported to other parts to initiate responses. Plant growth regulators include both natural and synthetic chemicals that influence plant growth and development when applied. The five major classes of natural plant hormones each have distinct functions such as cell elongation, dormancy, senescence and stress responses.

1. Plant Growth Regulators Chemical Messengers

7. What happens when auxin is added to a stem. The stem will bend away from the auxin. It elongates faster on the extra auxin side.

11. Auxin

22. Cytokinin