Zeatin (6-hydroxy-3-methyl-2-trans butenylaminopurine) was the first natural cytokinin isolated by Letham et. al. in 1964 from unripe maize grains or kernels. It is also isolated from coconut milk, peas, spinach, wheat, cotton, potato tubers and other parts. Cytokinins are plant hormones which are basic in nature, are either aminopurine or phenyl urea derivatives that promote cell division (cytokinesis) either
alone or in conjunction with auxin.