Family : Acanthaceae.
Giant Hygrophila is a beautiful and hardy plant that doesn't require much attention to grow well. It grows pretty large leaves, allowing a single stem to occupy a significant part of the tank. Left alone, it easily crosses the water surface and begins to assume its emersed form: the leaves are darker and harder, and the plant produces purple flowers that give out a pleasant scent. But in this case it also ends up shedding all underwater leaves, so frequent pruning is required if you don't want that. Any pruned stem may be buried in the gravel and will readily generate a new plant. Even without enriched soil, this plant will create strong roots. There seems to be some confusion in literature between the names Hygrophila corymbosa, Hygrophila stricta and Nomaphila stricta. Possibly these are all variants of the same species.