Mark Fricker started as a plant physiologist with Colin Willmer at Stirling, following a degree in Botany at Oxford, with his research focused on dissecting signal transduction pathways in stomatal physiology. This led to the development of quantitative imaging of Ca2+, pH and redox dynamics in plant and then fungal systems in Edinburgh with Tony Trewavas and Nick Read. This naturally evolved into the current interest in signalling and transport in networked systems that he has pursued since his appointment in Oxford in 1989. His experimental investigations cover a range of scales including confocal ratio imaging on a micron scale, radiolabel scintillation imaging at an intermediate scale, and network analysis and mathematical modelling to predict behaviour at a macro-scale, with over 100 publications and book chapters.