Coastal fen with Darlingtonia, Curry County
(John A. Christy, Oregon Biodiversity Information Center)

Fens (see also Serpentine fens) Most wetlands in Oregon that have been called "bogs" are actually fens, because they are hydrated by mineral-rich surface or groundwater, lack a domed peat profile, and have a pH generally higher than 5.5. Many fens, however, contain localized hummocks or lawns of Sphagnum with a pH as low as 4, and these are classified as "poor fens." Oregon's fens occur in depressions and on slopes hydrated by springs and seeps, particularly in interdunal troughs, headwall basins, and floodplains. Fens may also occur around the edges or over the surface of midslope slump or sag ponds in landslide topography. They are usually perennially saturated but local areas of surface drying are not uncommon. Fens may include patches of shrub swamp and forested wetland occurring on peat soils. Drainage, filling, peat mining, conversion to commercial cranberry or blueberry production, and plant succession have destroyed many fens, and losses continue to occur despite wetland regulations that were designed to protect them.

Map of Fens in Oregon

Habitat: Slopes, 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*
	Betula glandulosa / Carex aquatilis var. dives Wet Shrubland [Provisional] Dwarf birch / Sitka sedge (Murray 2000: 44; Christy 2004: 39)	G3S2	WC
	Betula glandulosa / Carex utriculata Wet Shrubland Dwarf birch / southern beaked sedge (NS)	G4S4	BR, EC, WC
	Boykinia major Fen [Provisional] Large boykinia (Murray 2000: 13; Christy 2004: 71)	G4S2	CR, WC
	Calamagrostis canadensis Western Wet Meadow Bluejoint reedgrass (Murray 2000: 13; Christy 2004: 73; Crowe et al. 2004: 138; Wells 2006: 146; NS)	G4S4	BM, EC, WC
	Caltha leptosepala Wet Meadow White marshmarigold (Murray 2000: 13; Christy 2004: 76; McCain et al. 2014: 70; NS)	G4S4	BM, CR, EC, WC
	Caltha leptosepala - Carex obnupta Fen [Provisional] White marshmarigold - slough sedge (Christy 2004: 77)	G3S1	CR
	Carex aquatilis var. aquatilis Wet Meadow Water sedge fen (Christy 2004: 82; Crowe et al. 2004: 81; Wells 2006: 125; Christy 2014: 20; NS)	G5S4	BM, BR, EC
	Carex aquatilis var. dives Fen Sitka sedge (Murray 2000: 14; Christy 2004: 83; Crowe et al. 2004: 84; Odion et al. 2013: 68; McCain et  al. 2014: 74, 79; NS)	G4S4	EC, KM, WC
	Carex aquatilis var. dives - Comarum palustre Fen Sitka sedge - purple marshlocks (Christy 2004: 84; NS)	G2S2	CR
	Carex buxbaumii Fen Buxbaum sedge (Christy 2004: 85; Crowe et al. 2004: 89; NS)	G3S2	WC
	Carex canescens Fen [Provisional] Gray sedge (Crowe et al. 2004: 90)	G5S2	BM, WC
	Carex cusickii Fen Cusick sedge (Murray 2000: 15; Christy 2004: 86; Crowe et al. 2004: 91; NS)	G3S2	BM, CR
	Carex lasiocarpa Fen Slender sedge (Christy 2004: 90; Crowe et al. 2004: 96; NS)	G4S2	BM, BR, WC
	Carex limosa Fen Mud sedge (Christy 2004: 92; Wells 2006: 135; NS)	G2S2	BM, EC, WC
	Carex luzulina Fen [Provisional] Woodrush sedge (Christy 2004: 93; Crowe et al. 2004: 101; Wells 2006: 142; Odion et al. 2013: 72)	G4S3	BM, EC, KM
	Carex obnupta Wet Meadow Slough sedge (Murray 2000: 16; Christy 2004: 96; NS)	G4S4	CR, WV
	Dulichium arundinaceum Shore Fen Threeway sedge Threeway sedge (Christy 2004: 110; Crowe et al. 2004: 76; NS)	G3S2	CR, EC, WC, WV
	Eleocharis quinqueflora Fen Few-flowered spikerush (Murray 2000: 15, 18; Christy 2004: 114; Crowe et al. 2004: 126; Wells 2006: 131; McCain et al. 2014: 110; NS)	G4S2	BM, BR, EC, WC
	Eleocharis quinqueflora - Carex scopulorum Wet Meadow Few-flowered spikerush - Mountain sedge	G3S3	BM, EC, WC
	Hypericum anagalloides Fen [Provisional] Bog St. John's wort (Murray 2000: 20)	G5S3	CR, WC
	Juncus balticus - Bistorta bistortoides Wet Meadow [Provisional] Baltic rush - American bistort (Murray 2000: 21; Christy 2004: 124)	G4S4	EC, WC
	Kalmia microphylla / Carex aquatilis var. dives Wet Shrubland [Provisional] Alpine laurel / Sitka sedge (Christy 2004: 41)	G3S2	WC
	Myrica gale / Carex (aquatilis var.dives, utriculata) Fen Sweet gale / (Sitka sedge, southern beaked sedge) (Murray 2000: 33; Christy 2004: 50; NS)	G3S1	CR
	Menyanthes trifoliata Herbaceous Vegetation [Provisional] Buckbean	G5S4	BM, CR, EC, WC, WV
	Nephrophyllidium crista-galli Fen [Provisional] Deer cabbage (Murray 2000: 19; Christy 2004: 131)	G4S1	WC
	Picea engelmannii / Eleocharis quinqueflora Swamp Woodland Engelmann spruce / small-flowered spikerush (Crowe et al. 2004: 444; NS)	G3S3	WC, EC
	Rhododendron columbianum / Carex obnupta / Sphagnum spp. Fen Western Labrador-tea / slough sedge / sphagnum (Christy 2004: 43; NS)	G2S2	CR
	Rhododendron columbianum / Carex scopulorum Fen [Provisional] Western Labrador-tea / mountain sedge (Crowe et al. 2004: 267; Wells 2006: 96)	G4S2	BM
	Rhododendron columbianum / Darlingonia californica / Sphagnum spp. Fen Western Labrador-tea / darlingtonia / sphagnum (Christy 2004: 45; NS)	G2S2	CR
	Tsuga heterophylla / Rhododendron columbianum / Carex obnupta - Lysichiton americanus Treed Bog Western hemlock / western Labrador tea / slough sedge - yellow skunk cabbage (Christy 2004: 35; NS)	G1S1	CR
	Rhododendron columbianum - Gaultheria shallon / Carex obnupta Fen Western Labrador tea - salal / slough sedge (Murray 2000: 33; Christy 2004: 42; NS)	G2S2	CR
	Rhododendron columbianum / Sanguisorba officinalis / Sphagnum spp. Fen Western Labrador tea / great burnet / sphagnum (Christy 2004: 48; NS)	G1S1	CR
	Rhododendron (columbianum, groenlandicum) - Myrica gale / Sphagnum spp. Fen Western Labrador-tea - sweet gale / sphagnum (Christy 2004: 47; NS)	G2S1	CR
	Sanguisorba officinalis - Carex aquatilis var. dives Fen [Provisional] Great burnet - Sitka sedge (Murray 2000: 25; Christy 2004: 140)	G2S2	CR, WC
	Sphagnum (angustifolium, capillifolium, fuscum, mendocinum, miyabeanum, pacificum, palustre) Fen [Provisional] Sphagnum (Murray 2000: 11, 12)	G3S2	CR, WV, WC
	Spiraea douglasii / Sphagnum spp. Fen Douglas spiraea / sphagnum (Christy 2004: 60; NS)	G3S1	WV
	Spiraea douglasii - Vaccinium uliginosum / Carex (aquatilis var. dives, exsiccata) Fen [Provisional] Douglas spiraea / sphagnum (Christy 2004: 60; NS)	G3S2	WC
	Spiraea douglasii - Vaccinium uliginosum / Carex obnupta - Deschampsia cespitosa Fen [Provisional] Douglas spiraea - bog bilberry / slough sedge - tufted hairgrass (Christy 2004: 59)	G3S2	CR
	Trichophorum cespitosum Pacific Fen Tufted clubrush (Murray 2000: 28; Christy 2004: 147; NS)	G5S1	WC
	Vaccinium caespitosum / Sanguisorba officinalis Fen Dwarf huckleberry / great burnet (Christy 2004: 61; NS)	G1S1	CR
	Vaccinium uliginosum / Carex aquatilis var. dives Wet Shrubland Bog blueberry / Sitka sedge (Murray 2000: 39; Christy 2004: 65; Crowe et al. 2004: 262; McCain et al. 2014: 125; NS)	G4S4	CR
	Vaccinium uliginosum / Carex obnupta Wet Shrubland [Provisional] Bog bilberry / slough sedge (Christy 2004: 63)	G3S3	CR
	Vaccinium uliginosum / Deschampsia caespitosa Wet Shrubland Bog blueberry / tufted hairgrass (Christy 2004: 64; NS)	G2S2	EC, WC
	Vaccinium uliginosum / Eleocharis quinqueflora Wet Shrubland [Provisional] Bog blueberry / few-flowered spikerush (Crowe et al. 2004: 259)	G4S2	EC, WC
	Xerophyllum tenax - Sanguisorba officinalis Meadow Bear-grass - great burnet (Christy 2004: 62; NS)	G1S1	CR, KM
	Xerophyllum tenax / Sphagnum spp. Meadow Bear-grass / sphagnum (Murray 2000: 29; NS)	G3S2	CR, WC

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