Fluid secretion called phytohormones or plant hormones is responsible for the chemical coordination in plants. These hormones are responsible for regulation of metabolic processes, plant growth, and development. They are synthesize away from their action site and are diffused there. 

Functions of different plant hormones.

• Auxin is responsible for plant growth.
• Cytokinin promotes cell-division in fast-growing plant parts. 
• Ethylene acts as an inhibitor and growth promoter.
• Abscisic acid regulates dormacy and abscission. It also inhibits plant metabolism.
• Gibberellin promotes bolting, fruit ripening, or sudden elongation of internodes just nefore flowering.