that's quite a broad nomer to be fussy about, do you mean the lowland varzea's, the Igarape's, black water, white water, Upper amazon, or coastal plains, in the dry season or in the wet season where the water can rise 30 feet.
There are some south american plants we use as houseplants.
Generalized qoute about the amazon lowlands: The main types of vegetation in the ecoregion include seasonally inundated or flooded forests (várzea and igapó), swamp forests (which are semi-permanently or permanently flooded), terra firme forests, and floating meadows. The areas surrounding the Amazonian rivers flood annually, lasting six months on average. Várzeas (flooded by whitewater rivers such as the Solimões, Amazon, Madeira, Purus, and Juruá) are generally more fertile than surrounding areas due to the deposition of fertile alluvial soils from the Andes. Igapó forests (flooded by black or clearwater rivers such as the Tapajós) grow on nutrient-poor white sandy soils. Common tree species in flooded forests include tachi (
Sclerolobium aureum), sorva (
Couma utilis),
Exellodendron coriaceum, and Piassava palm
Leopoldinia piassaba. Terra firme forests grow at higher elevations and include trees such as the Brazil nut (
Bertholletia excelsa). Many typical várzea species are also found in terra firme forests.
If you have more details about the location you want to copy, there is info about the local fauna in a country or habitat on the net. It needs searching but there is more available then a few years ago. Another spot for info is to be found in the diverse "biotope"- style challenges in the aquarium world. Some have done a lot of research and it can be found in the descriptions of their projects.
If you realy want to go specia,l you will probably want to hook up with a botanical garden/zoo and make some arrangement on getting old leaves. Or get a plant yourself (i did with the catappa, now i have a bag full of leaves every year)