Internal cytokinin levels influence growth and morphology in higher plants. The amount of cytokinin present in a plant or plant tissue is strongly controlled by a signalling pathway involving cytokinin oxidase (CKX) as one major component. Antisense inhibition of CKX activity leads to a stimulation of root growth, retardation of senescence and the production of a higher number of inflorescences. The novel class of substituted 6-anilinopurine derivatives inhibiting CKX activity leads to a similar effect on higher plants as the antisense technique.