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Carex stenoptila

F.J. Herm.

Riverbank Sedge

G3Vulnerable Found in 6 roadless areas NatureServe Explorer →
G3VulnerableGlobal Rank
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.155890
Element CodePMCYP03CX0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderCyperales
FamilyCyperaceae
GenusCarex
Other Common Names
Small-winged 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 Date2025-04-16
Change Date2014-10-30
Edition Date2025-04-30
Edition AuthorsFayette, Kim and Susan Spackman (1999), rev. A. Treher (2014), rev. Johnson, J. (2025)
Threat ImpactUnknown
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Number of Occurrences21 - 80
Rank Reasons
Carex stenoptila is a perennial sedge that occurs in Colorado, Montana, Utah, and Wyoming with possible collections in other western states. This species is somewhat difficult to identify and review of specimens by a Carex expert would help to clarify the species' range and number of occurrences. Due to its preference for remote alpine and subalpine habitats, little is known about this species' population, trends, or threats but some occurrences may be impacted by recreation or grazing.
Range Extent Comments
Carex stenoptila occurs in Colorado, Montana, Utah, and Wyoming (FNA 2002). Specimens collected in Idaho, Oregon, Washington, and New Mexico (GBIF 2025) are outside of the known range and should be reviewed by a Carex specialist. Range extent was estimated using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1994 and 2025 (CPNWH 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 73 occurrences rangewide (CPNWH 2025, GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).
Threat Impact Comments
Threats to this species are not well documented, but its streamside habitat may be impacted by recreation, excessive grazing, water diversions, and road maintenance (NatureServe 2025, Montana Natural Heritage Program 2025).
Ecology & Habitat

Description

Small-winged Sedge forms clumps with stems that are 2-8 dm high and which arise from short rhizomes. The few leaves, 1-4 mm wide, are flat and clustered near the base. Flowers are clustered in 7-10 spikes aggregated into a tight head at the top of the stem. The female perigynia occupy most of the spike, with only a few inconspicuous male flowers (recognized by old stamens) at the base. The light brown perigynia are narrowly lance-shaped and 4-5 mm long, with a gently tapered tip that is entire-margined, deeply cleft, and round in cross-section at the tip. There are 5-7 nerves on the convex outer face of the perigynia. The dark to pale brown scales are smaller than the perigynia that they subtend. There are 2 stigmas. The seed is lens-shaped and fills the body of the perigynium.

Diagnostic Characteristics

C. STENOPTILA belongs to a large group of very similar sedge species. A technical manual and hand lens or microscope will be needed for positive identification. In the more common C. MICROPTERA, the seed does not fill the flattened perigynia. C. PHAECOCEPHALA has scales as long as the perigynia. C. MACLOVIANA, C. MULTICOSTATA, and C. PACHYSTACHYA have more egg-shaped perigynia.

Habitat

Carex stenoptila grows in moist to dry rocky slopes and openings in conifer forests, stream and pond banks, and subalpine to alpine meadows (FNA 2002, Giblin 2025, Ackerfield 2015).
Terrestrial Habitats
Forest/WoodlandForest - Conifer
Palustrine Habitats
HERBACEOUS WETLANDRiparian
Other Nations (1)
United StatesN3
ProvinceRankNative
WyomingS3Yes
MontanaS2Yes
ColoradoS3Yes
WashingtonSNRYes
Threat Assessments
ThreatScopeSeverityTiming
Unknown/undeterminedUnknownUnknownUnknown

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)No
Roadless Areas (6)
Wyoming (6)
AreaForestAcres
Beartooth Proposed WildernessShoshone National Forest16,837
Campbell LakeMedicine Bow-Routt National Forest7,088
Encampment River AdditionMedicine Bow-Routt National Forest4,996
French CreekMedicine Bow-Routt National Forest5,928
Libby FlatsMedicine Bow-Routt National Forest11,107
Snowy RangeMedicine Bow-Routt National Forest29,660
References (18)
  1. Ackerfield, J. 2015. Flora of Colorado. Botanical Research Institute of Texas, Fort Worth, TX. 818 pp.
  2. Colorado State University Herbarium. 1999. "Colorado State University Herbarium Database". http://www.colostate.edu/Depts/Biology/Herbarium/ database.html. (May 15 1999).
  3. Consortium of Pacific Northwest Herbaria (CPNWH). 2025. Online database of vascular plant specimens from the Pacific Northwest. Online. Available: http://www.pnwherbaria.org/index.php (accessed 2025).
  4. Consortium of Pacific Northwest Herbaria (PNW). 2007. Pacific northwest herbaria portal. Available online at http://www.pnwherbaria.org/index.php.
  5. 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.
  6. Giblin, D. 2025. <i>Carex stenoptila</i>. Burke Museum Herbarium, University of Washington. Online. Available: https://burkeherbarium.org/imagecollection/taxon.php?Taxon=Carex%20stenoptila (Accessed 2025).
  7. Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
  8. iNaturalist. 2025. Online. Available: https://www.inaturalist.org (accessed 2025).
  9. Kartesz, J., and the Biota of North America Program (BONAP). 1998. A Synonymized Checklist of the Vascular Flora of the United States, Puerto Rico, and the Virgin Islands. http://plants.usda.gov.
  10. 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.
  11. Montana Natural Heritage Program. 1999. Biological Conservation Database. http://nris.state.mt.us/mtnhp. (May 15 1999).
  12. NatureServe. 2025. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  13. NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2024. Version: 1.1.1 (released Oct 01, 2024).
  14. Southwest Environmental Information Network (SEINet). 2014. Collections Databases. Online. Available: http://swbiodiversity.org/seinet/. Acessed 2014.
  15. Southwest Environmental Information Network (SEINet). 2025. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2025).
  16. University of Colorado Museum. 1999. Plant collections housed at the University of Colorado Herbarium as of 1999. University of Colorado, Boulder, CO.
  17. Weber, W.A., and R.C. Wittmann. 1996a. Colorado flora: Eastern slope. Revised edition. Univ. Press of Colorado, Niwot, Colorado. 524 pp.
  18. Weber, W.A., and R.C. Wittmann. 1996b. Colorado flora: Western slope. Univ. Press of Colorado, Niwot, Colorado. 496 pp.