The successful colonization of land by plants was accompanied by the diversification of their branching architecture. Differential accumulation of the hormone auxin is a shared feature of branching control in flowering plants and mosses, which diverged from their most recent common ancestor several hundred million years ago and underwent independent diversification of their architecture. However, whilst active intercellular polar transport of auxin is crucial for flowering plant branching control, it has a comparatively minor role in the moss Physcomitrium. Our data suggest instead that diffusion through plasmodesmata is the main route for auxin movement in the regulation of moss branching. However, how this mechanism is coordinated in space and time at the tissue and whole shoot levels and contributes to the emergence of robust auxin and branch distribution patterns is unknown. Moreover, how hormonal transport has been modified in evolution to produce novel branching forms remains also elusive. The PhD student to be hired will investigate these questions using a multiscale computational modelling approach and biological experiments to perturb hormone transport.