Abstract
Amphibious plants thrive in areas with fluctuating water levels, partly as a result of their capacity to make specialized leaves when submerged or emerged. The tailor-made leaves improve gas exchange underwater or prevent aerial desiccation. Aquatic leaves are thin with narrow or dissected forms, thin cuticles and fewer stomata. These traits can combine with carbon-concentrating mechanisms and various inorganic carbon utilization strategies. Signalling networks underlying this plasticity include conserved players like abscisic acid and ethylene, but closer inspection reveals greater variation in regulatory behaviours. Moreover, it seems that amphibious leaf development overrides and reverses conserved signalling pathways of their terrestrial counterparts. The diversity of physiology and signalling makes plant amphibians particularly attractive for gaining insights into the evolution of signalling and crop improvement.