This article is about marsh, a type of wetland. For other uses of the word marsh, see Marsh (disambiguation).
Freshwater marsh in Florida
In geography, a marsh, or morass, is a type of wetland which is subject to frequent or continuous inundation.[1] Typically a marsh features grasses, rushes, reeds, typhas, sedges, and other herbaceous plants (possibly with low-growing woody plants) in a context of shallow water. A marsh is different from a swamp, which has a greater proportion of open water surface, and is generally deeper than a marsh. In North America, the term swamp is used for wetland dominated by trees rather than grasses and low herbs.
Below water decomposition processes often produce marsh gas, which may through self-ignition manifest as Will o' the wisps (aka. Jack-a-lanterns or spirites).
Marshes are critically important wildlife habitats, often serving as breeding grounds for a wide variety of animal life.
Constructed wetlands featuring surface-flow design are usually in the form of a marsh.