Hello to this forum.

I am setting up a 75g paludarium for the third time.

We moved.

This time I am taking the next step. I live in Florida, and would like to stick with native plants, or at least from somewhere in North America. I am thinking of Duckweed, rooted into the 'land' protion of the palu. I used to do this with philodendron, which grew wildly well, entwining the above water driftwood and sending runners into the water. The real purpose of the philo was to complete the cycle: food in - plants out.
Will the Duckweed serve this purpose? Will the Duckweed survive with only its feet wet, spreading out over the water? If I don't like this weed, will I ever be able to rid the tank of its ornery presence? Will it filter out too much light from the submersed plants? Should I go with Saururus cernuus (Lizard's Tail) instead, or in addition?
The setup in a 75g, 48x18x21"tall paludarium, fully wet:
2x32 W T-8 el cheapo 'sunlight' bulbs
Airspace = 9"
Land = 18"w x 12"h (on the left) made of LECA, held back by a granite retaining wall
Water = 9 - 11" clear above substrate, fed by 'overland' river from a submersed sump pump (ViaAqua 1300) feeding a waterfall, no CO2
Substrates =
1" black beauty coarse coal slag in front
3" rock wool in back, under 1/2" coal slag
Filter = 1" bio=balls under egg crate under fiberglass window screen
In addition to the aforementioned Duckweed, I will have my background plants ending up emersed, with (probably) Hemianthus micranthemoides, (baby tears or pearlgrass) and Sagittaria subulata, (Dwarf Sag) as part of the front lawn, with Lobelia cardinalis (Cardinal Flower) as a showcase 'tree', along with Micranthemum umbrosum in the back. Juncus repens, Ludwigia repens, Ludwigia brevipes, Didiplis diandra (or Peplis diandra), and Bacopa caroliniana are the prime candidates for completing the S.E. U.S. bitope (flora anyway, the critters are another story). At least the Eastern Painted Turtle will be from these parts (if I can buy one without driving out of state).
P.S. - Where am I going to get these basically local plants?