Hygrophila corymbosa
Giant Hygro
Giant Hygro has larger leaves and a woody stem. Additional stems branch out from the main plant.
This plant often looses some leaves when transferred into an aquarium. I believe that usually when it's purchased the plant has been grown emersed.
Otherwise this is a hardy plant in bright light, once established it does very well. When transfering from one tank to another I haven't had any problems with leaf loss.
For more information about Hygrophila corymbosa please see my June 2006 column for TFH's "The Planted Tank," called The Genus Hygrophila.