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Carex swanii

(Fern.) Mackenzie

Swan's Sedge

G5Secure Found in 3 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.129963
Element CodePMCYP03DD0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderCyperales
FamilyCyperaceae
GenusCarex
Synonyms
Carex virescens var. swaniiFernald
Other Common Names
Carex de Swan (FR) Swan's sedge (EN)
Concept Reference
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-08-18
Change Date1984-02-29
Edition Date2025-08-18
Edition AuthorsSoteropoulos (2025)
Threat ImpactUnknown
Range Extent200,000 to >2,500,000 square km (about 80,000 to >1,000,000 square miles)
Number of Occurrences> 300
Rank Reasons
Carex swanii is a wide-ranging perennial graminoid found in forests and woodlands, openings, and scrub. It occurs in eastern North America from Nova Scotia west to Ontario, Canada, south to Georgia west to Mississippi, Arkansas, and Oklahoma in the United States. There are over 1500 estimated occurrences, which face threats from development, rights-of-way maintenance, logging, invasive species, and other threats in some places. Little is known about trends, but with a large range extent and large number of occurrences, abundant habitat, and broad habitat preferences, this species is considered secure.
Range Extent Comments
Carex swanii occurs in eastern North America from Nova Scotia west to Ontario, Canada, south to Georgia west to Mississippi, Arkansas, and Oklahoma in the United States (FNA 2002, Weakley and the Southeastern Flora Team 2025). Range extent was estimated to be over 2.4 million square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025 (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).
Occurrences Comments
By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025, it is estimated that there are over 1500 occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).
Threat Impact Comments
Although threats are not widely documented, this species is threatened by development, rights-of-way maintenance, logging, invasive species, and other threats in some places, though there is insufficient data, including anecdotal accounts, to understand scope and severity of threats for this species (NatureServe 2025). However, their overall impact is likely negligible given the species' broad range, large number of occurrences, and affinity for typically abundant habitats.
Ecology & Habitat

Habitat

Carex swanii grows in dry to wet-mesic, nutrient rich forests and woodlands, openings, and scrub (FNA 2002, Weakley and the Southeastern Flora Team 2025).
Terrestrial Habitats
Forest - HardwoodForest - MixedForest EdgeWoodland - HardwoodWoodland - MixedShrubland/chaparral
Other Nations (2)
United StatesN5
ProvinceRankNative
New YorkS5Yes
OklahomaS1Yes
IllinoisS3Yes
MissouriS3Yes
South CarolinaS2Yes
MarylandSNRYes
New JerseyS5Yes
IowaS1Yes
MaineSNRYes
West VirginiaS5Yes
WisconsinS1Yes
North CarolinaS3Yes
VirginiaS5Yes
MassachusettsSNRYes
KansasS1Yes
DelawareS5Yes
New HampshireSNRYes
GeorgiaS3Yes
Rhode IslandSNRYes
OhioSNRYes
KentuckyS5Yes
IndianaS5Yes
AlabamaSNRYes
District of ColumbiaSNRYes
MississippiS4Yes
VermontS5Yes
ArkansasS4Yes
MichiganSNRYes
ConnecticutSNRYes
TennesseeSNRYes
PennsylvaniaS5Yes
CanadaN4
ProvinceRankNative
British ColumbiaSNANo
Nova ScotiaS3Yes
OntarioS4Yes
QuebecS2Yes
New BrunswickSXYes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentUnknownUnknownUnknown
4 - Transportation & service corridorsUnknownUnknownUnknown
4.1 - Roads & railroadsUnknownUnknownUnknown
5 - Biological resource useUnknownUnknownUnknown
5.3 - Logging & wood harvestingUnknownUnknownUnknown
5.3.5 - Motivation unknown/unrecordedUnknownUnknownUnknown
8 - Invasive & other problematic species, genes & diseasesUnknownUnknownUnknown
8.1 - Invasive non-native/alien species/diseasesUnknownUnknownUnknown
8.1.1 - Unspecified speciesUnknownUnknownUnknown

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)No
Roadless Areas (3)
North Carolina (1)
AreaForestAcres
South Mills RiverPisgah National Forest8,588
South Carolina (1)
AreaForestAcres
Ellicott Rock 1Sumter National Forest301
Tennessee (1)
AreaForestAcres
Brushy RidgeCherokee National Forest7,469
References (8)
  1. Flora of North America Editorial Committee (FNA). 2002b. Flora of North America north of Mexico. Vol. 23. Magnoliophyta: Commelinidae (in part): Cyperaceae. Oxford Univ. Press, New York. xxiv + 608 pp.
  2. Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
  3. iNaturalist. 2025. Online. Available: https://www.inaturalist.org (accessed 2025).
  4. Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
  5. NatureServe. 2025. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  6. <p>NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2025. Version: 2.1.1 (released April 04, 2025).</p>
  7. Southwest Environmental Information Network (SEINet). 2025. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2025).
  8. Weakley, A.S., and Southeastern Flora Team. 2025. Flora of the southeastern United States Web App. Edition of February 18, 2025. University of North Carolina Herbarium (NCU), North Carolina Botanical Garden, University of North Carolina, Chapel Hill. Online. Available: https://fsus.ncbg.unc.edu (accessed 2025).