In geography, a marsh, also referred to as a morass, is a type of wetland defined as a low lying, poorly drained section of land, which is often if not always covered in water. It can normally be found at the edge of lakes and streams, and act as a transition between the aquatic and terrestrial ecosystems. They are dominated by grasses such as rushes and reeds, and have few to no woody areas. If woody plants are present they tend to be low-growing shrubs. This form of vegetation is what differentiates marshes from other types of wetland such as swamps, which are dominated by trees, and bogs, which are wetlands that have accumulated deposits of acidic peat.