Well, some plants like water sprite have a very shallow root system and feed mostly from the leaves....wysteria is the same...and they are really good plants for sucking up nitrates and phosphates and stuff you don't want in your aquarium...except to feed the plants...lol...
Others are stem plants that feed mostly from the root and require root based ferts...like those fert sticks...and also a better quality substrate.
The fresh vs. saltwater plants are an idea I hadn't thought of...lol....but that would be good to have a list of those plants for the fresh, salt and brackish tanks. Not sure how many plants there actually are for marine tanks though...I think corals and inverts take the place of plants in a marine tank....not sure though since I YET to have a marine tank...
Don't forget the foreground...midground...background catagory.........I'm not that familiar with the fert requirements of aquatic plants...but I think some prefer more iron and such than others....Maybe there's someone here with more knowledge in that area that can help out....who's that guy...."plantman"?? I forget his name here, but he's quite knowledgeable in those issues.
OH...and lighting requirements....low, medium, high and how many watts per gallon would provide the appropriate range..........hmm...would it be easier to just have a list of the more familiar sized tanks...such as 10, 20, 29, 55 and so on and just have a graph of sorts with LOW being one column....MED another...etc...with the amount of wattage required to equal a Low, Med or high lighted tank listed in the appropriate column...........Jeesh....I'm confusing myself here !!! LOL ! YOu getting any of this???? cause I'm not sure I am !

:duh: