Physiognomy and Structure: No Data Available

Floristics: This wetland association is dominated by submersed and emergent rooted vegetation under 1 m tall. The species composition can be quite variable, but this community is easy to recognize by the bright green, nearly pure stands of Eleocharis palustris. Vegetation cover can be sparse to dense (10-90%), but Eleocharis palustris is the dominant species, and the only species with 100% constancy. Other species, when present, can contribute as much as 40% cover, but never exceed that of the Eleocharis palustris cover. Some of this variation is described from Colorado (Baker and Kennedy 1985, Kittel et al. 1999b). Co-occurring species in low-elevation stands on the western slope can include Phalaris arundinacea (= Phalaroides arundinacea), Juncus arcticus ssp. littoralis (= Juncus balticus), Hordeum jubatum, Equisetum spp., Pascopyrum smithii, Schoenoplectus americanus (= Scirpus americanus), Sparganium angustifolium, species of Lemna and Potamogeton, as well as the introduced Melilotus officinalis and Bromus inermis. On the eastern plains of Colorado co-occurring species can include Leersia oryzoides, Schoenoplectus pungens (= Scirpus pungens), Panicum virgatum, Carex pellita (= Carex lanuginosa), and Spartina pectinata. At montane elevations, other graminoids, such as Carex aquatilis, Carex utriculata, and Deschampsia cespitosa, are present. Forb cover is typically low but can be occasionally abundant (30%) in some stands. Forb species include Pedicularis groenlandica, Rhodiola integrifolia, and Caltha leptosepala.In stands from eastern Washington, associates include Carex utriculata, Cicuta douglasii, and species of Glyceria and Potamogeton. In northwestern Nebraska, stands are dominated by Eleocharis acicularis and Eleocharis palustris which commonly cover the bottoms of the pools and emerge above the water as the pools dry out. Ephemeral submersed aquatics, such as Callitriche palustris (= Callitriche verna), Potamogeton diversifolius, and Marsilea vestita, may be present. As the pools dry out in mid-summer, ephemeral annual forbs, such as Limosella aquatica and Plagiobothrys scouleri, may appear. By late summer Amaranthus californicus and Gnaphalium palustre may dominate in the lowest parts of the depression (Steinauer and Rolfsmeier 2003). In southwestern South Dakota, vegetation is composed of nearly homogeneous stands of Eleocharis palustris. Other emergents, such as Polygonum amphibium, Marsilea vestita, and Eleocharis ovata, are occasionally found. Herbaceous cover is greater than 75% except in areas of deeper open water where floating and submerged aquatic plants occur, including Bacopa rotundifolia and Heteranthera limosa (H. Marriott pers. comm. 1999). In lower elevation Utah stands, Glaux maritima, Distichlis spicata, and Juncus arcticus ssp. littoralis are important associates (Brotherson and Barnes 1984).Few stand data are available for Colorado examples. Generally, it appears that this community is dominated by Eleocharis palustris, forming a scattered to dense overstory, often with few associated species. Commonly associated graminoids include Hordeum jubatum and Pascopyrum smithii. Forbs present may include Atriplex argentea, Polygonum aviculare, and Rorippa sinuata (Baker and Kennedy 1985). The higher elevation stands may include a slightly different suite of species, but no stand data are available. Ramaley (1942) described a Distichlis spicata-dominated salt meadow on a lakeshore in the San Luis Valley which was ringed by Eleocharis palustris. Communities in Utah include Eleocharis acicularis and Alopecurus aequalis as likely associates (Padgett et al. 1989).

Dynamics:  The hydrological regime is critically important to this association. Most stands are seasonally to permanently flooded, although some occur under intermittently to temporarily flooded conditions. Baker and Kennedy (1985) suggest that domestic livestock grazing may tend to result in increases in Hordeum jubatum, Bassia scoparia, and Polygonum aviculare. However, Hansen et al. (1988a) suggest that palatability of Eleocharis palustris is low for both domestic and wild animals, but that heavy grazing may increase this rhizomatous species and spread it onto adjacent sites. Trampling damage (especially soil compaction) may occur to this type when animals heavily use the sites supporting it, particularly during drought years (Hansen et al. 1988a). Water level fluctuations over a year of greater than 1 m will not support this type (Hansen et al. 1988a).