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Soils

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 or slightly alkaline

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 Alopecurus aequalis Marsh [Provisional]
Short-awn foxtail (Christy 2016: 12)
G4S3 BR
wetland type image Athyrium filix-femina-Scirpus microcarpus Marsh [Provisional]
Lady fern (Christy 2004: 67)
G4S3 CR
wetland type image Bidens cernua Marsh [Provisional]
Nodding beggars-tick marsh (Murray 2000: 12; Christy 2004: 69)
G4S3 WV
wetland type image Bidens frondosa Marsh [Provisional]
Leafy beggars-tick (Christy 2004: 70)
G4S4 WV
wetland type image Calamagrostis nutkaensis - Carex spp. - Juncus spp. Grassland
Pacific reedgrass - sedge - rush (Christy 2004: 74; NS)
G2S1 CR
wetland type image Carex interrupta Marsh [Provisional]
Green-fruited sedge (Crowe et al. 2004: 94)
G3S2 EC
wetland type image Carex leporinella Marsh [Provisional]
Sierra hair-sedge (Crowe et al. 2004: 100; Wells 2006: 136)
G4S4 BM
wetland type image Carex obnupta Wet Meadow
Slough sedge (Murray 2000: 16; Christy 2004: 96; NS)
G4S4 CR, WV
wetland type image Carex utriculata Wet Meadow
Southern beaked sedge (Murray 2000: 16; Christy 2004: 100; Crowe et al. 2004: 120; Wells 2006: 127; McCain et al. 2014: 91; NS)
G5S4 CR, EC, WC
wetland type image Carex vesicaria Wet Meadow
Inflated sedge (Crowe et al. 2004: 123; Wells 2006: 129; NS)
G4S4 BM, BR, CR, EC
wetland type image Eleocharis acicularis Marsh
Needle sedge (Christy 2004: 111; Crowe et al. 2004: 74; NS)
G4S4 EC, WC
wetland type image Eleocharis bella Mudflat [Provisional]
Delicate spikerush (Crowe et al. 2004: 75)
G3S1 BM
wetland type image Eleocharis obtusa Mudflat [Provisional]
Blunt spikerush (Christy 2004: 112)
G4S3 WV
wetland type image Eleocharis palustris Marsh
Creeping spikerush (Murray 2000: 17; Christy 2004: 113; Crowe et al. 2004: 66; Christy 2014: 33; NS)
G5S5 BM, BR, CB, CR, EC, KM, WV
wetland type image Equisetum fluviatile Marsh
Water horsetail (NS)
G4S3 CR, EC, WC
wetland type image Eragrostis hypnoides - Gnaphalium palustre Mudflat
Creeping lovegrass - lowland cudweed (Christy 2004: 118; NVC)
G2S1 WV
wetland type image Euthamia occidentalis Mudflat
Western goldenrod (Christy 2004: 119; NS)
G3S3 WV
wetland type image Glyceria borealis Wet Meadow
Northern mannagrass (Crowe et al. 2004: 64; NS)
G4S4 BR
wetland type image Glyceria grandis Wet Meadow
Reed mannagrass (NS)
G2S2 BR
wetland type image Glyceria striata Herbaceous Vegetation
Fowl mannagrass (Murray 2000: 19; Christy 2004: 120; Crowe et al. 2004: 147; NS)
G3S3 BM, EC, WV
wetland type image Hippuris vulgaris Aquatic Vegetation
Common mare's tail (Christy 2004: 121; NS)
G5S3 BM, BR, CR, EC, WV
wetland type image Hydrocotyl ranunculoides Marsh [Provisional]
Floating water-pennywort (Christy 2004: 122)
G5S3 CR
wetland type image Juncus effusus Pacific Coast Marsh
Pacific rush marsh (Titus 1996-1998: 1; Murray 2000: 21; Christy 2004: 125)
G5S3 CR, KM, WV
wetland type image Juncus ensifolius Marsh [Provisional]
Dagger-leaf rush (Titus 1996-1998: 4)
G4S4 KM
wetland type image Juncus nevadensis Marsh [Provisional]
Sierra rush (Christy 2004: 126; Crowe et al. 2004: 131)
G4S4 EC
wetland type image Lilaeopsis occidentalis Marsh [Provisional]
Lilaeopsis (Christy 2004: 128)
G3S3 CR, WV
wetland type image Ludwigia palustris - Persicaria hydropiperoides Aquatic Vegetation
Water purslane - waterpepper (Christy 2004: 129; NS)
G3S3 CR, KM, WV
wetland type image Lysichiton americanus - (Athyrium filix-femina) Marsh [Provisional]
Skunk cabbage (Diaz & Mellen 1996: 167; Murray 2000: 22)
G4S4 WV
wetland type image Myriophyllum hippuroides Marsh [Provisional]
Western water-milfoil bed (Kunze 1994: 47, 57)
G3S2 WV
wetland type image Nuphar polysepala Aquatic Vegetation
Yellow pond-lily (Murray 2000: 23; Christy 2004: 132; Crowe et al. 2004: 62;Wells 2006: 156; Odion et al. 2013: 64; NS)
G5S5 BM, BR, CR, EC, WC, WV
wetland type image Oenanthe sarmentosa Marsh
Water-parsley (Murray 2000: 23; Christy 2004: 133; McCain 2004: 192; NS)
G4S4 CR, WV
wetland type image Paspalum distichum Marsh
Knotgrass (Christy 2004: 134; NS)
G5S3 CR, WV
wetland type image Persicaria amphibia Marsh [Provisional]
Water smartweed (Christy 2004: 135)
G5S3 BR, WV
wetland type image Persicaria lapathifolia Marsh [Provisional]
Curltop ladysthumb (Christy 2014: 41)
G3S2 BR
wetland type image Potentilla rivalis Marsh [Provisional]
Brook cinquefoil (Christy 2014: 45)
G3S2 BR
wetland type image Ranunculus flammula Aquatic Vegetation [Provisional]
Creeping buttercup (Christy 2004: 138)
G5S3 CR, WC
wetland type image Sagittaria latifolia Aquatic Vegetation
Wapato (Christy 2004: 139; NS)
G3S2 WV
wetland type image Schoenoplectus acutus Marsh
Hardstem bulrush (Christy 2004: 141; Crowe et al. 2004: 70; NS)
G5S5 BM, BR, CB, CR, EC, KM, WV
wetland type image Schoenoplectus tabernaemontani Temperate Marsh
Softstem bulrush (Crowe et al. 2004: 70; NS)
G5S5 BM, BR, CB, CR, EC, KM, WC, WV
wetland type image Scirpus microcarpus Marsh
Small-fruited bulrush (Murray 2000: 25; Christy 2004: 142; Crowe et al. 2004: 134; Wells 2006: 133; NS)
G4S4 BM, CB, CR, EC, KM, WC, WV
wetland type image Sparganium angustifolium Aquatic Vegetation
Narrowleaf bur-reed (Murray 2000: 26; Christy 2004: 144; Crowe et al. 2004: 58; Wells 2006: 156; NS)
G4S3 CR, WV
wetland type image Sparganium eurycarpum Aquatic Vegetation
Broadfruited bur-reed (Christy 2004: 145; Christy 2014: 47; NS)
G4S3 BR, CB, WV
wetland type image Torreyochloa pallida var. pauciflora Marsh [Provisional]
Weak mannagrass (Murray 2000: 27; Christy 2004: 146; Crowe et al. 2004: 65)
G2S3 BM, CR, EC, WV
wetland type image Typha (latifolia, angustifolia) Western Marsh
Cattail (broadleaf cattail, narrowleaf cattail) (Murray 2000: 29; Christy 2004: 149; Crowe et al. 2004: 56; Wells 2006: 157; NS)
G5S5 CR

Authored by John A. Christy, Wetlands Ecologist, (ORBIC) Oregon Biodiversity Information Center (2012 rev. 2017)