Are there any trees that prefer to grow on the floor of water bodies but protrude to the air? Specifically, those that prefer salt water or grow on shallow sea.
Mangrove swamp trees and shrubs immediately spring to mind. There are many species that fall into this category of trees that grow in intertidal and costal locations. They prefer locations where salt and freshwater mix, known as 'brackish water'.
All roots require oxygen and the species that fall into this category have developed roots that protrude above the surface, called pneumatophores.
Here is an excellent website with more information http://www.fao.org/docrep/010/ai387e/AI387E06.htm