Mangrove and seagrass occupy different environments within an estuary, and both potentially respond to environmental stressors such as, nutrient loading, sedimentation, turbidity and climate change. Therefore, they could be useful indicators of the health of the estuary. However, there are common misunderstandings about the function of flowering plants such as mangrove and seagrass in the marine environment that can lead to contradictory and possibly inappropriate actions by the public. For example, pressure to protect mangroves and remove seagrass. This talk will discuss the interactions between physical processes within estuaries and mangrove and seagrass, consider the changes that have occurred in the distribution of these plants over the recent past, and suggest possible causes for these changes.