Thanks, Snipe. That leads me to an additional question.
I believe terrestrial plants can only exchange CO2 and O2 through their stoma. Some terrestrial plants can handle submerged roots for shorter periods and some for years depending on the exchange mechanisms in the roots. (And that is what makes them "terrestrial" plants.)
Obviously, aquatic plants must be able to do the exchange through either leaves on the surface of the water, or leaves that can utilize dissolved CO2 in the water.
Terrestrial plants (generally) get their nitrogen, phosphorus, and sulfur from the soil.
This then leads to the specific question I should have asked in the OP:
Do aquatic plants have the ability to pull nutrients (nitrogen, phosphorus, sulfur, etc.) directly from the water, or do they utilize their roots to pull those nutrients from the bottom of the pond as those nutrients build up in the soil and muck?
Or possibly, do some classes of aquatic plants take nutrients directly from the water, and some must take up nutrients from the soil?
