Description. In areas with relatively stable climatic conditions, Emergent Wetlands maintain the same appearance year after year. In other areas, such as the prairies of the central United States, violent climatic fluctuations cause them to revert to an open water phase in some years (Stewart and Kantrud 1972). Emergent Wetlands are found throughout the United States and occur in all Systems except the Marine. Emergent Wetlands are known by many names, including marsh, meadow, fen, prairie pothole, and slough. Areas that are dominated by pioneer plants which become established during periods of low water are not Emergent Wetlands and should be classified as Vegetated Unconsolidated Shores or Vegetated Streambeds.

Subclasses and Dominance Types.

• Persistent. -- Persistent Emergent Wetlands are dominated by species that normally remain standing at least until the beginning of the next growing season. This Subclass is found only in the Estuarine and Palustrine Systems.
  Persistent Emergent Wetlands dominated by saltmarsh cordgrass (Spartina alterniflora), saltmeadow cordgrass (S. patens), big cordgrass (S. cynosuroides), needlerush (Juncus roemerianus), narrow-leaved cattail (Typha angustifolia), and southern wild rice (Zizaniopsis miliacea) are major components of the Estuarine systems of the Atlantic and Gulf Coasts of the United States. On the Pacific Coast, common pickleweed (Salicornica Virginica), sea blite (Suaeda californica), arrow grass (Triglochin maritimum), and California cordgrass (Spartina foliosa) are common dominants.
  Palustrine Persistent Emergent Wetlands contain a vast array of grasslike plants such as cattails (Typha spp.), bulrushes (Scirpus spp.), saw grass (Cladium jamaicense), sedges (Carex spp.); and true grasses such as reed (Phragmites australis), manna grasses (Glyceria spp.), slough grass (Beckmannia syzigachne), and whitetop (Scolochloa festucacea). There is also a variety of broad-leaved persistent emergents such as purple loosestrife (Lythrum salicaria), dock (Rumex mexicanus), waterwillow (Decodon verticillatus), and many species of smartweeds (Polygonum).

• Nonpersistent. -- Wetlands in this Subclass are dominated by plants which fall to the surface of the substrate or below the surface of the water at the end of the growing season so that, at certain seasons of the year, there is no obvious sign of emergent vegetation. For example, wild rice (Zizania aquatica) does not become apparent in the North Central States until midsummer and fall, when it may form dense emergent stands. Nonpersistant emergents also include species such as arrow arum (Peltandra virginica), pickerelweed (Pontederia cordata), and arrowheads (Sagittaria spp.). Movement of ice in Estuarine, Riverine, or Lacustrine Systems often removes all traces of emergent vegetation during the winter. Where this occurs the area should be classified as Nonpersistant Emergent Wetland.