Auxin, cytokinin, gibberellin, ethylene and abscisic acid are plant hormones or phytohormones. Auxin promotes cell elongation, delay fall of leaves and apical dominance. Gibberellin also helps in cell elongation, break dormancy of seeds, delay senescence and induce parthenocarpy. Ethylene is a gaseous hormone that helps in fruit ripening. Cytokinin helps in cell division. ABA has a inhibitory function.