What is the term for aquatic plants that grow completely underwater?

The term for aquatic plants that grow completely underwater is "submersed." These plants are adapted to live entirely below the water's surface, typically having structures that facilitate photosynthesis and respiration while submerged. Submersed plants contribute to aquatic ecosystems by providing habitat and food for various aquatic organisms, as well as playing a vital role in nutrient cycling and water quality improvement.

In contrast, emersed plants are those that grow partially above the water surface, free-floating plants remain on the water surface and do not attach to the substrate, and rooted-floating plants are anchored to the bottom but have their leaves and stems floating on the water surface. Understanding these distinctions is essential for effective aquatic plant management and conservation practices.