Changes to Accommodate Air

• Plants had to develop certain biological structures in order to survive the many elements air brings that differ from those in the water. For instance, as land plants are not constantly surrounded by water, they had to develop cuticle and guard cells to help prevent drying out, according to Utah State University. They also developed specialized stomatal cells in order to acquire carbon dioxide from the air for photosynthesis, which is abundant in air but not water.
  
  

Land Plants and Salt Water

• Most land plants cannot tolerate high concentrations of salt, but some coastal and marsh plant species developed specialized cells that allow them to live partially out of the water yet drink salt water. Mangroves, for instance, developed cellular structures that allow them to almost completely filter out salt from their water sources. True land plants lost the ability to produce these salt-filtering structures.
  
  

Standing Without Support

• Land plants had to be able to support themselves without the help of water. Most land plants have a substance called lignin that allows them to grow tall while also protecting against embolisms, or obstructions in their veins, that could prevent the flow of essential water and nutrients.