Plant hormones (or phytorythmistic substances) can be classified to teams according to their physiological action or their chemical structure, or in some cases both of them.

Auxins
a. Natural: IAA
b. Synthetic:   IBA
                     NAA
                     β-NOA
                     2,4-D
                     2,4,5-D
                     4-CPA
                     3-CPA
                     naphthyl-acetamide
                     β-N-m-tolyphthalamic acid

Gibberellins
a. Natural: gibberellin acid (GA3)
b. Synthetic:   gibberellin A4
                      gibberellin A7 ...

Cytokinins  
a. Natural: zeatin
b. Synthetic:   kinetin
                     N-6-benzyl-9-tetrahydropyrane adenine
                     N-6-benzyladenine ...

Abscisic Acid
a. Natural: abscisic acid (ABA)
b. Synthetic:   -

Ethylene
a. Natural: ethylene (C2H4)
b. Synthetic:   ethephon

Phytochrome     
a. Natural: phytochrom
b. Synthetic:  -

Brassinosteroids (BRs)
a. Natural: brassinolide
b. Synthetic:  -

Polyamines
a. Natural: putrescine
                 spermidine
                 spermine
                 cadaverine
b. Synthetic:  -

Morphactines
a. Natural: -
b. Synthetic:   chlorflurenol
                      flurenol
                      chlorflurenol methyl
                      dichlorflurenol methyl ...

Growth Retardants
a. Natural: -
b. Synthetic:   ancymidol
                      chlormequat chloride
                      chlorphonium chloride
                      daminozide
                      mericuat chloride
                      paclobutrazol ...

Growth inhibitors
a. Natural: -
b. Synthetic:   chlorpropham
                      propham
                      maleic hydrazide
                      tecnazene

Gameticides
a. Natural: -
b: Synthetic:   2,3-dichloro-isobutyric acid
                     DPX-3778
                     RH-531

Apical dominance (chemical pruning)
a. Natural: -
b. Synthetic:   dikegulak sodium
                      maleic hydrazide
                      n-octanol, n-decanol ...

Defoliants
a. Natural: -
b. Synthetic:   merphos
                     thidiazuron
                     dimethipin

Desiccants
a. Natural: -
b. Synthetic:   diquat
                      paraquat
                      endothal
                      sodium chlorate

Herbicide antidotes, safeners
a. Natural: -
b. Synthetic:   naphthalic anhydride
                     R-25788
                     cyometrinil

Αντιδιαπνευστικά
a. Natural: CO2
b. Synthetic:   silicone
                      8-hydroxyquinoline
                      polyvinyl chloride