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Carex arcta

Boott

Northern Clustered Sedge

G5Secure Found in 1 roadless area NatureServe Explorer →

G5SecureGlobal Rank

Least concernIUCN

UnknownThreat Impact

Identity

Unique IDELEMENT_GLOBAL.2.159448

Element CodePMCYP030X0

Record TypeSPECIES

ClassificationSpecies

Classification StatusStandard

Name CategoryVascular Plant

IUCNLeast concern

Endemicoccurs (regularly, as a native taxon) in multiple nations

KingdomPlantae

PhylumAnthophyta

ClassMonocotyledoneae

OrderCyperales

FamilyCyperaceae

GenusCarex

Other Common Names

Bear Sedge (EN) Carex dru (FR) Narrow Sedge (EN) northern cluster sedge (EN) Northern Cluster 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 Date1985-04-05

Edition Date2025-08-18

Edition AuthorsSoteropoulos (2025)

Threat ImpactUnknown

Range Extent>2,500,000 square km (greater than 1,000,000 square miles)

Number of Occurrences81 to >300

Rank Reasons

Carex arcta is a wide-ranging perennial graminoid found in a variety of wetland habitat types, including wet meadows, evergreen swamp woods, swampy thickets, and river or lake shores. It occurs in northern and western North America, from Alaska, United States, and throughout Canada (except Nunavut and Nova Scotia) south to New Hampshire, Vermont, New York, Michigan, Wisconsin, Minnesota, Wyoming, Idaho, and California in the United States. There are over 250 estimated occurrences, which face threats from development, pipeline right-of-way maintenance, recreational activities, invasive species, and other threats in some places. Little is known about trends, but with a large range extent and large number of occurrences, this species is considered secure.

Range Extent Comments

Carex arcta occurs in northern and western North America, from Alaska, United States, and throughout Canada (except Nunavut and Nova Scotia) south to New Hampshire, Vermont, New York, Michigan, Wisconsin, Minnesota, Wyoming, Idaho, and California in the United States (FNA 2002, Lukas et al. 2012). While reported from Massachusetts (FNA 2002), specimens are unknown (Native Plant Trust 2025). Range extent was estimated to be over 11 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 250 occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025). This graminoid is likely overlooked in photo-based observations, underrepresented in herbaria collections, not all collections are georeferenced, and anecdotal comments support the likelihood that there are over 300 occurrences rangewide.

Threat Impact Comments

Although threats are not widely documented, this species is threatened by development, pipeline right-of-way maintenance, recreational activities, 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

Description

Carex arcta is a tightly clumped sedge with short underground stems. The soft stems are about 2 feet high, rough at the top, and often overtopped by the pale or grayish green, soft, flat, narrow leaves only 1/8" wide. The leaf sheath is conspicuously purple-dotted and concave near the summit. The ligule is pointed and longer than wide. The 5-15 spikes are all clustered together at the tops of the stems. Each spike has 10-20 or more perigynia crowded together. The perigynia are egg-shaped with a definite beak that is strongly toothed. They have obvious nerves on the outside face with faint nerves on the inside face. They are 2-3 mm long and 1.2-1 .5 mm wide. The perigynia scales are pointed, slightly shorter than the perigynia, clear with a green center and often brown-tinged.

Habitat

Carex arcta grows in "swampy (coniferous) woods and thickets, [and] wet meadows," sometimes bordering streams or on lake shores (FNA 2002, Native Plant Trust 2025).

Palustrine Habitats

HERBACEOUS WETLANDSCRUB-SHRUB WETLANDFORESTED WETLANDRiparian

Other Nations (2)

United StatesN5

Province	Rank	Native
New Hampshire	SNR	Yes
Washington	SNR	Yes
Oregon	SNR	Yes
Wisconsin	SNR	Yes
New York	S1	Yes
California	S1	Yes
Montana	S4	Yes
Vermont	S1	Yes
Michigan	S3	Yes
Wyoming	S1	Yes
Minnesota	SNR	Yes
Maine	SNR	Yes
Alaska	SNR	Yes
Idaho	SNR	Yes

CanadaN5

Province	Rank	Native
New Brunswick	S3	Yes
Island of Newfoundland	SH	Yes
Northwest Territories	SU	Yes
British Columbia	S5	Yes
Manitoba	S1	Yes
Ontario	S4	Yes
Quebec	S4	Yes
Alberta	S2	Yes
Labrador	SU	Yes
Yukon Territory	S3	Yes
Saskatchewan	S2	Yes

Threat Assessments

Threat	Scope	Severity	Timing
1 - Residential & commercial development	Unknown	Unknown	Unknown
4 - Transportation & service corridors	Unknown	Unknown	Unknown
4.2 - Utility & service lines	Unknown	Unknown	Unknown
6 - Human intrusions & disturbance	Unknown	Unknown	Unknown
6.1 - Recreational activities	Unknown	Unknown	Unknown
8 - Invasive & other problematic species, genes & diseases	Unknown	Unknown	Unknown
8.1 - Invasive non-native/alien species/diseases	Unknown	Unknown	Unknown
8.1.1 - Unspecified species	Unknown	Unknown	Unknown

Plant Characteristics

DurationPERENNIAL

Economic Value (Genus)No

Roadless Areas (1)

Washington (1)

Area	Forest	Acres
Dry Canyon Breaks	Colville National Forest	4,821

References (9)

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.
Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
iNaturalist. 2025. Online. Available: https://www.inaturalist.org (accessed 2025).
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.
Lukas, L.E., B.E. Nelson and R.L. Hartman. 2012. A Floristic inventory of vascular plants of the Medicine Bow National Forest and vicinity, southeastern Wyoming, U.S.A. Journal of the Botanical Research Institute of Texas 6(2):759-787.
Native Plant Trust. 2025. Go Botany website. Online. Available: https://gobotany.nativeplanttrust.org (accessed 2025).
NatureServe. 2025. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
<p>NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2025. Version: 2.1.1 (released April 04, 2025).</p>
Southwest Environmental Information Network (SEINet). 2025. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2025).

Carex arcta

Description

Habitat

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