Plant Hormones - substances produced by plants, which at low concentrations regulate
morphological and physiological processes of the plant. Hormones can move within the
plant from the generated to the action site, or be produced at the action site. The term
hormone is restricted to products that occur naturally in plants (named endogenous).
Belonging to both the previous classes, there are: auxins, gibberellins, cytokinins, absci‐
sic acid and ethylene. It is considered, for the bio-regulator acts, that it must primarily
bind to a receptor on the plasmatic membrane of the cell.