Many discoveries in science have been accidental which is true for plant hormones' discovery too. The five major groups of plant growth regulators have all been discovered accidentally.

• When Charles Darwin and his son Francis Darwin observed the coleoptiles of canary grass, they noticed that it responded to unilateral illumination by bending and growing towards the light source. Auxin was isolated by F.W. Went from tips of coleoptiles.

• Foolish seedling disease of rice was caused by the fungal pathogen Gibberella fujikuroi. The symptoms of which were first reported by Kurosawa who noticed that uninfected rice developed these symptoms when gibberellins were added.

• Only when auxins were added, the callus of stems proliferated. This was observed by F. Skoog and his co-workers .

• Skoog and Miller crystallised the cytokinesis promoting substance called kinetin.

• Scientists confirmed the release of a gaseous substance from ripened oranges - ethylene.