How does chemical coordination occur in plants?

In plants, chemical coordination occurs by plant hormones. Plant hormones are chemical substances which are produced at specific pare of the plant and then are diffused to other part of the plant. Most of the plant hormones promote growth in certain plant parts, e.g. auxin, gibberellins and cytokinin. Abscisic acid is a plant hormone which inhibits growth. Shedding of leaves or ripe fruits is facilitated by abscisic acid.