Fluid motion is of fundamental importance for plant survival, growth and development. This distribution of water and nutrients is achieved by hydraulics. Fluid flow also plays a key role in long-distance signalling, allowing plants to adapt to environmental challenges. Fluid dynamics thus maintains plant vitality and health. In this chapter we derive the basic governing equations for fluid motion from first principles and describe the pertinent boundary conditions. Pressure-driven flow in a tube is discussed as a conceptualised model of fluid transport in the plant’s vasculature system. We also discuss solute transport with particular reference to the individual roles played by convection and diffusion and the enhanced dispersive effect that can be achieved when these two effects work in unison.