Intertidal salt and brackish marshes are found throughout the Pacific Coast, from Kodiak Island and south-central Alaska to the central California coast. They are primarily associated with estuaries or coastal lagoons. Salt marshes are limited to bays and behind sand spits or other locations protected from wave action. Typically these areas form with a mixture of inputs from freshwater sources into coastal saltwater, so they commonly co-occur with brackish marshes. This is a small-patch system, confined to specific environments defined by ranges of salinity, tidal inundation regime, and soil texture. Patches usually occur as zonal mosaics of multiple communities. They vary in location and abundance with daily and seasonal dynamics of freshwater input from inland balanced against evaporation and tidal flooding of saltwater. Summer-dry periods result in decreased freshwater inputs from inland. Hypersaline environments within salt marshes occur in "salt pans" where tidal water collects and evaporates. Characteristic plant species include Distichlis spicata, Monanthochloe littoralis, Limonium californicum, Jaumea carnosa, Salicornia spp., Suaeda spp., Batis maritima, and Triglochin spp. Low marshes are located in areas that flood every day and are dominated by a variety of low-growing forbs and low to medium-height graminoids, especially Salicornia virginica, Distichlis spicata, Schoenoplectus maritimus (= Scirpus maritimus), Schoenoplectus americanus (= Scirpus americanus), Carex lyngbyei, and Triglochin maritima. In Alaska, tidal marshes are often dominated by near-monotypic stands of Carex lyngbyei, while the frequently inundated lower salt marshes are often dominated by Eleocharis palustris or Puccinellia spp. Other common species in Alaska include Hippuris tetraphylla, Plantago maritima, Cochlearia groenlandica (= Cochlearia officinalis), Spergularia canadensis, Honckenya peploides, or Glaux maritima. In the Cook Inlet and Alaska Peninsula, Carex ramenskii may be an associated species. High marshes are located in areas that flood infrequently and are dominated by medium-tall graminoids and low forbs, especially Deschampsia caespitosa, Argentina egedii, Juncus balticus, and Symphyotrichum subspicatum (= Aster subspicatus), and in Alaska Poa eminens, Argentina egedii, Festuca rubra, and Deschampsia caespitosa. Transition zone (slightly brackish) marshes are often dominated by Typha spp. or Schoenoplectus acutus. Atriplex prostrata (= Atriplex triangularis), Juncus mexicanus, Phragmites spp., Cordylanthus spp., and Lilaeopsis masonii are important species in California. The invasive weed Lepidium latifolium is a problem in many of these marshes. Rare plant species include Cordylanthus maritimus ssp. maritimus.
Information Source: http://www.natureserve.org/explorer/