Physiognomy and Structure: This is an herbaceous wetland. Woody plants are sparse to absent, but height and cover of herbaceous plants can vary greatly among sites and even at a given site over time. Herbaceous cover can vary from sparse to complete, and height can vary from short (<0.5 m) to tall (2 m), though most sites have an herbaceous canopy between 1 and 2 m tall. If there is a deep water edge (water deeper than will support these marshes), then the vegetation is typically fairly open and sparse along that edge.

Floristics: These marshes have a variety of species present though Typha spp. (Typha latifolia, Typha angustifolia, or, in the south, Typha domingensis) and Schoenoplectus spp. (most commonly Schoenoplectus acutus, Schoenoplectus americanus, Bolboschoenus fluviatilis (= Schoenoplectus fluviatilis), Bolboschoenus maritimus (= Schoenoplectus maritimus), and Schoenoplectus tabernaemontani) are by far the most common species throughout the range. Within individual marshes there may be zonation where different species grow. Some favor the deeper, more permanently flooded sections, while others can tolerate or even prefer the shallower sections that dry out more frequently. Other species common locally or in parts of this group''s range include Carex spp. (especially Carex aquatilis and Carex atherodes), Eleocharis palustris, Eleocharis compressa, Leersia oryzoides, Polygonum pensylvanicum, Polygonum lapathifolium, Sagittaria spp. (in wetter areas), Scolochloa festucacea, Sparganium spp., and Triglochin maritima. On drier margins or when water levels are low, Calamagrostis stricta, Equisetum hyemale, Glyceria spp., and Spartina pectinata can sometimes be found though these are more common in other vegetation types. Species abundance can change from year to year at a given site depending on water levels.

Dynamics:  Hydrologic changes are the main natural dynamic affecting this group. These marshes are fed by larger drainage basins, and sometimes also by groundwater sources, and are thus more hydrologically stable than other basin wetlands in the Great Plains, but they still occur in a climate that is semi-arid or the dry end of temperate so water can evaporate quickly. This group occurs on sites flooded for most or all of the growing season, and these conditions need to persist at any given site for multiple years for this group to become established, but longer-term precipitation cycles result in longer-term changes in water levels that can change the vegetation at any given site from wet meadow to the deeper marshes in this group and back (Kantrud et al. 1989a). Fire can spread from adjacent uplands, particularly in late summer or fall, and dense Typha spp. or Schoenoplectus spp. can provide abundant fuel. Fires can affect the composition of these marshes by removing standing and fallen litter which allows more light to reach the surface but also reduces the amount of snow trapped during the winter (in the northern parts of the range of this group) and thus can reduce water levels the following year. Many sites have been affected by agricultural practices either through draining and conversion to cropland or through trampling and grazing by livestock. Herbivory by muskrats (Ondatra zibethicus) can alter vegetation cover and composition.