What is the biggest problem for plants living in salt water?
The high level of salt causes normal plants to shrivel because the high salt concentration actually extracts water from the cell (due to simple diffusion) causing death to the plant. Seaweed and other marine plant life are exceptions because they are covered with a special layer of tissue that prevents that from happening. That and marine plants are able to handle a high salt environment. If you put a normal potted plant in a bath of salt water, chances are it would shrivel and lose its rigidity over the next few hours.
