Marshes form in basins that seasonally, periodically or permanently support standing water. They may be dominated by bulrushes, sedges, and other tall plants that can survive in deep standing water. Meadows are typically ground water fed treeless wetlands that are not peat accumulating. Springs form where ground water discharges to the soil surface, forming wet areas, or flowing water. Springs may discharge fresh, acid, carbonate rich, or saline ground water, and the communities that form are entirely dependent upon the discharging water. Many springs support endemic plants, invertebrates, or even fish.