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Wetlands

Freshwater Marshes

Freshwater Marsh with Wapato, Multnomah County

Freshwater marsh with wapato, Multnomah County
(John A. Christy, PSU Oregon Biodiversity Information Center)

Freshwater marshes (see also Freshwater tidal wetlands) occur in depressions and around the edges of lakes, ponds, rivers, and streams where surface water is present for all or most of the growing season and the soil is perennially wet (freshwater tidal marshes that are treated separately in the following section). They are characterized by emergent herbaceous vegetation, usually graminoids such as spikerush (Eleocharis spp.), sedges (Carex spp.), bulrushes (Schoenoplectus spp.), bur-reed (Sparganium spp.), cattails (Typha spp.), and various grasses. Broadleaved herbs and shrubs may also be present. They are particularly well known as breeding or foraging sites for birds. Freshwater marshes are found throughout the state, but many thousands of acres have been diked, drained, and farmed.

Freshwater Marshes Map

Freshwater Marshes Map

Habitat: Edges of rivers, streams, lakes and ponds, or larger expanses in basins and flats
Water regime: Perennially to seasonally flooded
Water chemistry: Fresh

Ecoregion*: BM = Blue Mountains, BR = Northern Basin and Range, CB = Columbia Basin, CR = Coast Range, EC = East Cascades, KM = Klamath Mountains, WC = West Cascades, WV = Willamette Valley  
Scientific & Common Name Global & State Rank Ecoregion*
wetland type image Athyrium filix-femina Herbaceous Vegetation [Provisional]
Lady fern
G4S3 CR
wetland type image Bidens cernua Herbaceous Vegetation [Provisional]
Nodding beggars-tick marsh
G3S3 WV
wetland type image Bidens frondosa Herbaceous Vegetation [Provisional]
Leafy beggars-tick
G4S4 WV
wetland type image Calamagrostis nutkaensis - Carex spp. - Juncus spp. Herbaceous Vegetation
Pacific reedgrass - sedge spp. - rush spp.
G2S1 CR
wetland type image Carex amplifoliaHerbaceous Vegetation
Bigleaf sedge
G3S3 BM, CR, EC
wetland type image Carex exsiccata Herbaceous Vegetation [Provisional]
Western inflated sedge
G3S3 CR, WC, WV
wetland type image Carex interrupta Herbaceous Vegetation [Provisional]
Green-fruited sedge
G3S2 EC
wetland type image Carex leporinella Herbaceous Vegetation [Provisional]
Sierra hair-sedge
G4S4 BM
wetland type image Carex lyngbyei Herbaceous Vegetation
Lyngby sedge freshwater marsh
G4S3 BM
wetland type image Carex obnupta Herbaceous Vegetation
Carex obnupta
G4S4 CR, WV
wetland type image Carex utriculata Herbaceous Vegetation
Beaked sedge
G5S4 BM, BR, CR, EC, WC
wetland type image Carex vesicaria Herbaceous Vegetation
Inflated sedge
G4S4 BM, BR, CR, EC
wetland type image Eleocharis acicularis Herbaceous Vegetation
Needle sedge
G4S4 EC, WC
wetland type image Eleocharis obtusa Herbaceous Vegetation [Provisional]
Blunt spikerush
G4S3 WV
wetland type image Eleocharis palustris Herbaceous Vegetation
Creeping spikerush
G5S5 CR, WV, KM, WC, EC, CP, BM, BR
wetland type image Equisetum arvense Herbaceous Vegetation
Common horsetail
G5S5 BM, CR, EC, WC, WV
wetland type image Equisetum fluviatile Herbaceous Vegetation
Water horsetail
G4S3 CR, EC, WC
wetland type image Eragrostis hypnoides - Gnaphalium palustre Herbaceous Vegetation [Provisional]
Creeping lovegrass - lowland cudweed
G2S1 WV
wetland type image Euthamia occidentalis Herbaceous Vegetation [Provisional]
Western goldenrod
G3S3 WV
wetland type image Glyceria borealis Herbaceous Vegetation
Northern mannagrass
G4S4 BR
wetland type image Glyceria grandis Herbaceous Vegetation
Reed mannagrass
G2S2 BR
wetland type image Glyceria striata Herbaceous Vegetation
Fowl mannagrass
G3S3 BM, EC
wetland type image Hippuris vulgaris Herbaceous Vegetation
Common mare's tail
G5S3 BM, BR, CR, EC, WV
wetland type image Hydrocotyl ranunculoides Herbaceous Vegetation [Provisional]
Floating water-pennywort
G5S3 CR
wetland type image Juncus effusus var. brunneus Pacific Coast Herbaceous Vegetation
Pacific rush marsh
G5S3 CR, WV
wetland type image Juncus ensifolius Herbaceous Vegetation [Provisional]
Dagger-leaf rush
G4S4 KM
wetland type image Juncus nevadensis Herbaceous Vegetation [Provisional]
Sierra rush
G4S4 EC
wetland type image Lilaeopsis occidentalis Herbaceous Vegetation [Provisional]
Lilaeopsis
G3S3 CR, WV
wetland type image Ludwigia palustris - Polygonum hydropiperoides Herbaceous Vegetation [Provisional]
Water purslane - waterpepper
G3S3 CR, KM, WV
wetland type image Lysichiton americanus Herbaceous Vegetation [Provisional]
Yellow skunk cabbage
G4S4 EC, WC
wetland type image Myriophyllum hippuroides Herbaceous Vegetation [Provisional]
Western water-milfoil bed
G3S2 WV
wetland type image Nuphar polysepala Herbaceous Vegetation
Rocky Mountain pond-lily
G5S5 BM, CR, EC, WC, WV
wetland type image Oenanthe sarmentosa Herbaceous Vegetation [Provisional]
Water-parsley
G4S4 CR, WV
wetland type image Polygonum amphibium Herbaceous Vegetation [Provisional]
Water smartweed
G5S3 BR, WV
wetland type image Sagittaria latifolia Herbaceous Vegetation [Provisional]
Wapato
G3S2 WV
wetland type image Schoenoplectus acutus Herbaceous Vegetation
Hardstem bulrush
G5S5 CR, WV, KM, WC, EC, CP, BM, BR
wetland type image Schoenoplectus tabernaemontani Herbaceous Vegetation
Softstem bulrush
G5S5 BM, CP, CR, EC, BR, WV, KM, WC, WC
wetland type image Scirpus microcarpus Herbaceous Vegetation
Small-fruited bulrush
G4S4 BM, CP, CR, EC, BR, WV, KM, WC
wetland type image Sparganium angustifolium Herbaceous Vegetation
Narrowleaf bur-reed
G4S3 CR, WV
wetland type image Sparganium eurycarpum Herbaceous Vegetation
Broadfruited bur-reed
G4S3 BR, CR, WV
wetland type image Typha (latifolia, angustifolia) Western Herbaceous Vegetation
Cattail (broadleaf cattail, narrowleaf cattail)
G5S5 CR

Authored by John A. Christy, Wetlands Ecologist, (ORBIC) Oregon Biodiversity Information Center (2012)