South American plants

[Guest]

I'm looking for some recommendations for South American plants, since I'm setting up a biotope tank.
The tank is a 20 high (24"x12"x16") and will house a pair of Microgeophagus Ramirezi (blue rams - they're already in there) and some tetras (haven't decided on a species yet), maybe some small SA catfish.
Tank has 2 watts/gallon of lighting, could be increased, could be decreased.

Thanks