There are five major classes of plant hormones (a.k.a. Plant growth regulators (Pgr's)) with perhaps a few others as candidates to take that place in the future. The five major hormone classes are Auxins, Cytokinins(CK’s), Ethylene, Gibberellins (GA’s), and Abscisic Acid (ABA). Recently it has been suggested that Brassinosteroids (BA’s), Jasmonates (JA’s), Salicylates (SA’s), and Polyamines are new classes of major hormones.

See also: Hormone

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