Two common wetland plants, Phragmites australis and Typha angustifolia, have different preferences for water depth. Typha angustifolia can survive in deeper water than Phragmites australis. In experiments, Phragmites australis did not survive in the deepest water and had lower biomass, nitrogen content, and photosynthesis compared to Typha angustifolia. The differences in water depth tolerance and response to root aeration may explain why these plants grow in different water depths. Understanding these differences is important for managing these plants in wetlands.