hydrophytes

Hydrophytes are plants adapted to living in aquatic environments, spanning freshwater bodies such as ponds, lakes, rivers, and wetlands, and extending to some coastal or brackish areas. They may be completely submerged, float on the surface, or be rooted in the substrate with portions above water. Their life strategies are tied to water availability, oxygen diffusion, and light conditions.

They are often categorized by growth habit: submerged hydrophytes (for example Elodea, Vallisneria, Ceratophyllum) live mostly underwater; floating-leaved species (such as Nymphaea and Nuphar) have leaves that float on the surface; free-floating plants (Lemna, Spirodela, Pistia) are not anchored to the bottom; and emergent hydrophytes (Typha, Phragmites, Scirpus) are rooted underwater but extend stems and leaves above the waterline.

Anatomical and physiological adaptations support aquatic life. Many hydrophytes have extensive aerenchyma to transport gases and provide buoyancy; the cuticle is often reduced and stomata may be absent or limited to certain leaves. Roots are frequently modified for anchorage and storage rather than water uptake, and some species lack true roots. Carbon uptake can involve dissolved CO2 and bicarbonate, with various mechanisms to overcome limited gas exchange.

Reproduction occurs sexually through flowers that reach or emerge at the water surface in some species, and asexually by fragmentation, runners, or rhizomes in others. Hydrophytes contribute to ecosystem structure by providing habitat, stabilizing sediments, and influencing light and nutrient dynamics; they can improve water quality but dense stands may crowd other vegetation. Some species are invasive in non-native regions, while others indicate environmental change or water quality.