In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants. More in general, the word can be used for any low-lying and seasonally waterlogged terrain. In Europe and in agricultural literature low-lying meadows that require draining and embanked polderlands are also referred to as marshes or marshland.
Marshlands are often noted within wetlands, as seen here in the New Jersey Meadowlands at Lyndhurst, New Jersey, U.S.
Marsh in shallow water on a lakeshore
White water lilies are a typical marsh plant in European areas of deeper water.
Many kinds of birds nest in marshes; this one is a yellow-headed blackbird.
A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently for years or decades or seasonally for a shorter periods. Flooding results in oxygen-free anoxic processes prevailing, especially in the soils. The primary factor that distinguishes wetlands from terrestrial land forms or water bodies is the characteristic vegetation of aquatic plants, adapted to the unique anoxic hydric soils. Wetlands are considered among the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal species. Methods for assessing wetland functions, wetland ecological health, and general wetland condition have been developed for many regions of the world. These methods have contributed to wetland conservation partly by raising public awareness of the functions some wetlands provide. Constructed wetlands are designed and built to treat municipal and industrial wastewater as well as to divert stormwater runoff. Constructed wetlands may also play a role in water-sensitive urban design.
Marshlands are often noted within wetlands, as seen here at the Jamaica Bay Wildlife Refuge in New York City.
Sunrise at Viru Bog, Estonia
Wetlands contrast the hot, arid landscape around Middle Spring, Fish Springs National Wildlife Refuge, Utah
Humid wetland in Pennsylvania before a rain.