Algae are categorized under which type of aquatic plant?

Algae are categorized as plants without true stems or leaves because they exhibit a simple structure that does not have the complex organization seen in higher plants. Algae are primarily composed of groups of cells that perform photosynthesis, but they do not develop true roots, stems, or leaves like vascular plants do. This classification reflects their fundamental differences in anatomy and physiology.

In contrast, the other types of aquatic plants mentioned do have true structures and are organized differently. Emersed plants are those that grow partially above water, such as cattails. Submersed plants live entirely underwater and have specialized adaptations to thrive in that environment, such as structures allowing for better buoyancy. Floating plants, like water lilies, have adaptations that allow them to float on the water surface. Each of these categories represents different adaptations and complexities that algae do not possess.