Chemical Coordination in Plants: Plants do not have a nervous system but they coordinate their activities by means of some chemicals called the plant hormones or phytohormones. Depending upon the effect on plants growth, phytohormones have been grouped into the following categories-   Growth Promoters – These are the phytohormones which stimulate the growth of the plants. These include auxin, gibberellins, cytokinins, florigen, etc. Growth Inhibitors – these are the phytohormones which retard the growth & other physiological activities of the plants. These include Abscisic acid, ethylene, dormin, etc. Auxin: was the first hormone to be discovered. Auxins were discovered … Continue reading Chemical Coordination in Plants & Animals