Physiognomy and Structure: Stands are variable depending upon degree of perennial to seasonal saturation or flooding, and degree of salinity/alkalinity of substrates. Of the true halophytes, Allenrolfea occidentalis alliance stands have the highest tolerance for salt, followed by Sarcocornia utahensis, Sarcobatus vermiculatus, and Atriplex nuttallii (Goodman 1973).

Floristics: Sites exhibit a range of soil moisture and salinity/alkalinity, from slightly brackish perennial springs to rarely inundated, hypersaline evaporate crusts. Areas with higher water tables and lower salinity support productive brackish marshes with tall graminoids and grasses such as Schoenoplectus americanus, including the ecologically similar Schoenoplectus pungens sensu FNA Editorial Committee (2002b), Phragmites australis, Typha angustifolia, Eleocharis spp., and Bolboschoenus maritimus along with taller forbs such as Helianthus nuttallii, Solidago spectabilis, and Euthamia occidentalis. West of the Great Plains these occur where freshwater springs emerge through salty or alkaline substrate, or creeks, streams or rivers flow through edges of salt flats or coastal salt marshes. These marshes tend to have steep moisture gradients to drier adjacent saline vegetation of the seasonal or ephemeral wetland component of this division.

Seasonal or ephemeral wetlands in the division have saline soils, a shallow to moderately deep water table and flood intermittently, but remain dry for most growing seasons. Salt crusts are common throughout. The flats are intermittently, seasonally to semipermanently flooded, usually retaining subsurface water into the growing season and drying completely only in drought years. They are often found in strongly saline-alkaline playa-like depressions, old lakebeds or in floodplains of major river systems where seasonal water inputs are limited, and often include some groundwater seepage in a matrix of mixed salt desert scrub. High rates of evaporation lead to alkaline water and soil conditions, with layers of salt-encrusted soils often accumulating near seeps. Perennial seeps often have bands of distinctive vegetation radiating outward, each with lower moisture requirements and higher salinity tolerance; for example, Anemopsis californica, Cressa truxillensis, Juncus cooperi, Juncus arcticus ssp. littoralis (= Juncus balticus), Bassia americana (= Kochia americana), Leymus triticoides, Leymus cinereus, Muhlenbergia asperifolia, Puccinellia spp. (including the endemic Puccinellia howellii), Salicornia rubra, Sesuvium verrucosum, Spartina gracilis, Sporobolus airoides, and Triglochin maritima. These herb stands also are reduced in stature as they decrease in moisture and increase in salinity, and ultimately are often surrounded by a low patchy turf of Distichlis spicata. These herbaceous stands grade into seasonal or ephemeral wetlands on playas or salt pannes, or irregularly flooded lowlands where halophytic shrubs, tend to be characteristic. Occasional shrubs tolerant of brackish but not highly salty water may occur in and adjacent to these herbaceous wetlands. These include Prosopis glandulosa, Prosopis pubescens, and Pluchea sericea (larger stands of these species occur in other riparian divisions).

Brackish marshes from the Great Plains eastward share many of these same species but also include related species such as Atriplex patula, Poa arida, Iva annua, Suaeda calceoliformis, and tend to grade into surrounding grasslands or agricultural landscapes. An increase in precipitation during exceptionally wet years can dilute the salt concentration in the soils, allowing for less salt-tolerant species such as Pascopyrum smithii or Hordeum jubatum to become dominant. In general there are no highly evaporative hypersaline playas or flats east of the 100th meridian.

Shrublands characteristic of salty warm or cool desert conditions are prevalent in this division throughout the West, but are not common from the Great Plains eastward. These periodically flooded shrublands consist of open to moderately dense stands of woody chenopods. Soils with shallow briny water tables tend to be dominated or codominated by succulent phreatophytes, including Allenrolfea occidentalis, Arthrocnemum subterminale, Sarcobatus vermiculatus, or Suaeda moquinii (= Suaeda nigra). Less salty soils with lower or no appreciable water table tend to have non-succulent-leaved species such as Atriplex canescens, Atriplex confertifolia, Atriplex gardneri, Atriplex parryi, Atriplex spinifera, Grayia spinosa, or Krascheninnikovia lanata. Areas of overlap occur with herbs such as Distichlis spicata, Bassia americana, and short perennial subshrubs such as Suaeda spp. and Frankenia salina (in California) occurring with taller shrubs of Atriplex or Sarcobatus.

Dynamics:  Temporal shifts in salinity, inundation, and soil moisture strongly affect the dynamics of both herbaceous and woody components of this division. Although most western stands are subject to long periods of drought and are relatively stable in salinity, the more eastward and northward in range, the more likely are shifts in salinity based on periods of drought (higher) or wet cycles (lower). Permanent springs and seeps may also be affected by increases or decreases in salinity. In California, stands of Atriplex spinifera, Atriplex confertifolia, Suaeda moquinii, and other shrubs tend to be short-lived and shift depending on drought cycles (Sawyer et al. 2009). Others have found similar drought-related cycles in Allenrolfea or Sarcobatus (Trent et al. 1997, Gul et al. 2001).