A study looked at how different water plants in a wetland can clean up polluted water. They tested plants like Vallisneria, Eichhornia, and Phragmites, and found that Eichhornia was best at removing pollutants like nitrogen and organic matter. The plants helped clean up the water by absorbing and breaking down the pollutants. The study also showed that a wetland system with different stages can clean water even better, but only up to a certain point before it becomes less effective.