Senescence and ageing in plants and cyanobacteria

This article is an introductory synopsis of the papers on senescence and ageing, presented in this issue of Physiologia Plantarum. The major results of the individual articles have been put into contiguity and are briefly reviewed in the light of the literature. Genetically controlled processes and stochastic reactions closely interact in the course of ageing of an individual. This holds for the cells and tissues of green plants as well as for the strongly specialized heterocysts of filamentous cyanobacteria.