The Clue Rootless water plant
The Answer ALGA
The answer "ALGA" fits the clue "Rootless water plant" because algae are simple aquatic plants that do not have roots. They can float freely in water and are often found in oceans, lakes, and ponds. Algae play an important role in the ecosystem by producing oxygen and serving as food for various aquatic creatures. This makes them a perfect match for the clue given.