CBSE Class 9 Answered

Salt-loving plants i.e. halophytes, such as the seagrasses and mangroves, generally have a lower concentration of water molecules (lower water potential) in their root cells so they can take in water. They maintain lower water potentials in their roots by having higher internal salt concentrations than seawater and by losing water at the leaf surface. Since high internal salt concentrations can be lethal to plant cells, some halophytes can excrete excess salt through their leaves and stems. Most phytoplankton (algae) and seaweeds are isotonic. That means that the water content of their tissues is essentially the same as the surrounding sea water. They
do not expend energy to control their water balance.