What are marine or freshwater plants with no true stems or leaves?

Marine and freshwater plants without true stems or leaves are typically classified as non-vascular plants. Examples include certain types of algae, such as green algae (Chlorophyta) and red algae (Rhodophyta), which lack the complex structures found in vascular plants. Additionally, some bryophytes, like mosses, can also inhabit aquatic environments, although they are primarily terrestrial. These plants rely on diffusion for nutrient and water transport, which is suitable for their aquatic habitats.