Variable Sedge

Carex polymorpha Muhl.

Carex polymorpha line drawing
Britton, N.L., and A. Brown (1913); downloaded from USDA-Plants Database.

Monocotyledoneae (Monocots)
Cyperaceae (Sedge Family)
State Protection
Not Listed
Not listed or protected by New York State.
Federal Protection
Not Listed
State Conservation Status Rank
Presumed Extirpated from New York - No existing locations known anywhere in New York despite intensive searches of historical locations and other appropriate habitat, and virtually no likelihood of rediscovery.
Global Conservation Status Rank
Vulnerable globally - At moderate risk of extinction due to rarity or other factors; typically 80 or fewer populations or locations in the world, few individuals, restricted range, few remaining acres (or miles of stream), and/or recent and widespread declines.


Did you know?

This species was considered for federal listing under the Endangered Species Act but was withdrawn when additional populations were found. Still, there are fewer than 45 extant populations in the world (Everett 2001).

State Ranking Justification

There are no known populations within New York today, but there are ten historical sites. Extensive surveys of the Long Island locations have failed to locate this plant and habitat has been severely diminished through urbanization and other types of habitat alteration. With New York is located within the middle of this sedge's range, the liklihood of finding it within New York is pretty low.

Short-term Trends

The species is considered extirpated in New York. The last report was from 1929.

Long-term Trends

The plant was historically known from 10 sites in New York but all of these sites no longer have habitat for this species. Therefore, Carex polymorpha is presumed extirpated in New York. The last report was from 1929.

Conservation and Management


This species is considered extirpated at all of its historical locations due to habitat alteration and destruction. Mostly this is the result of urbanization. Based on these New York sites, urbanization has been the highest threat.

Research Needs

All the historical sites for Carex polymorpha in New York (Queens, Nassau, and Suffolk Counties) are considered extirpated. Most of these sites are in areas now completely urbanized. Botanist working on Long Island or in southeastern New York should be aware of how to identify this species and keep an eye out for it in potential habitat. Due to the fact that the areas where this sedge used to grow have been destroyed, more of a concerted effort is not needed.



In New York the species has been reported from open dry ground on a sandy bank of a reservoir, the edge of swampy woods, the edge of a bog, and dry sandy open scrub (New York Natural Heritage Program 2005). Thin woods with sandy soils (Rothrock and Reznicek 2002). Carex polymorpha occurs in sandy soils with low or high organic content and little or substantial duff. Sometimes the soils are loams. Sites often have a clay layer below the sandy surface soils creating seasonally saturated conditions. Many sites are just upslope of more regularly inundated wetlands. Sites occur in the open and less vigorously in the shade. (Standley and Dudley 1989). Occurs in uplands or adjacent to wetlands in strongly acidic friable soils that are seasonally saturated. Habitats where it occurs include forests, woodlands, shrubby, and open sites (Rawinski 1988). Dry sandy open woods and clearings (Fernald 1970).

Associated Ecological Communities

  • Appalachian oak-hickory forest* (guide)
    A hardwood forest that occurs on well-drained sites, usually on ridgetops, upper slopes, or south- and west-facing slopes. The soils are usually loams or sandy loams. This is a broadly defined forest community with several regional and edaphic variants. The dominant trees include red oak, white oak, and/or black oak. Mixed with the oaks, usually at lower densities, are pignut, shagbark, and/or sweet pignut hickory.
  • Coastal plain poor fen* (guide)
    A wetland on the coastal plain fed by somewhat mineral-rich groundwater and slow decomposition rates of plant materials in the wetland (and thus develops peat). Plants are generally growing in peat composed primarily of Sphagnum mosses with some grass-like and woody components.
  • Gravel mine*
    An excavation in a gravel deposit from which gravel has been removed. Often these are dug into glacial deposits such as eskers or kames. Vegetation may be sparse if the mine is active; there may be substantial vegetative cover if the mine has been inactive for several years. Near-vertical slopes are used by bank swallows for nesting sites.
  • Pine barrens shrub swamp* (guide)
    A shrub-dominated wetland that occurs in shallow depressions in the coastal plain, often as the transition zone between a coastal plain pond shore and either pitch pine-scrub oak barrens or pitch pine-oak forest.
  • Pitch pine-oak forest* (guide)
    A mixed forest that typically occurs on well-drained, sandy soils of glacial outwash plains or moraines; it also occurs on thin, rocky soils of ridgetops. The dominant trees are pitch pine mixed with one or more of the following oaks: scarlet oak, white oak, red oak, or black oak.
  • Pitch pine-oak-heath woodland* (guide)
    A pine barrens community that occurs on well-drained, infertile, sandy soils. The structure of this community is intermediate between a shrub-savanna and a woodland. Pitch pine and white oak are the most abundant trees.
  • Pitch pine-scrub oak barrens* (guide)
    A shrub-savanna community that occurs on well-drained, sandy soils that have developed on sand dunes, glacial till, and outwash plains.

* probable association but not confirmed.

Associated Species

  • Carex vestita (velvet sedge)
  • Comptonia peregrina (sweet-fern)
  • Gaultheria procumbens (wintergreen, teaberry)
  • Gaylussacia baccata (black huckleberry)
  • Kalmia latifolia (mountain laurel)
  • Lygodium palmatum (climbing fern, Hartford fern)
  • Pinus rigida (pitch pine)
  • Pteridium aquilinum var. latiusculum
  • Quercus alba (white oak)
  • Quercus ilicifolia (scrub oak, bear oak)
  • Quercus rubra (northern red oak)
  • Rhododendron canadense (rhodora)
  • Schizachyrium scoparium ssp. scoparium
  • Vaccinium angustifolium (common lowbush blueberry)
  • Vaccinium pallidum (hillside blueberry)


New York State Distribution

The species was historically known only from Long Island and New York City (Queens, Nassau, and Suffolk Counties). All historical populations are considered extirpated. The Shawangunk Ridge also provide some potential habitat but the species has never been found there.

Global Distribution

Extant in Connecticut, Massachusetts, Maine, New Hampshire, New Jersey, Pennsylvania, Rhodes Island, Virginia, and West Virginia. Historical records from Delaware, Maryland, New York. Some states with only one population.

Identification Comments

General Description

This sedge is an herbaceous grass-like perennial herb. Reproductive shoots are up to 60 cm tall. Leaf width is 2.5-5.0 mm wide. It spreads vegetatively by elongate rhizomes with one or a few shoots arising from nodes along the rhizomes.

Identifying Characteristics

All shoots are annual and are produced singly or in small clumps from nodes of the elongate rhizomes. Overwintering perennating shoot tips bend rather than stab, under gentle pressure. In shaded habitats as opposed to more open environments, there are fewer reproductive culms present. Leaves are up to 45 cm long, 2.5-5.0 mm wide, and are pale green (yellowing later in the season). Proximal leaves of reproductive shoots have bladeless sheaths that are red-brown to purple-brown and do not disintegrate into a ladder-fibrillose (pinnate network of persistent veins) condition. The abaxial surface of the leaf sheaths are densely papillose. Ligules are 2-10 mm long and are longer than wide. Bracts all have a sheathing base. Distal 1-3 spikes are staminate. Proximal 0-3 spikes are pistillate or androgynous, often branch at the base of the spikes, and are 1.5-3.5 cm long by 7.5-10.0 mm wide. Perigynia are 4.2-6.8 mm long by 1.5-2.5 mm wide, papillose, have a purple tinged obliquely bidentate beak. (Rawinski 1988, Standley 1989, Rothrock and Reznicek 2002)

Best Life Stage for Proper Identification

This species is easiest to identify when in immature to mature fruit although some populations especially in shaded environments will have few or no flowering/fruiting culms.

Similar Species

Although from a different section, Carex vestita has been considered to be morphologically similar. Standley (1989) lists the following differences. Carex vestita has bladeless sheaths 8-10 cm long (vs. 5 cm. long); apex of bladeless sheaths with a sharply acute apex (vs. broadly acute); bladeless sheaths disintegrating into a pinnate network of persistent veins (vs. not disintegrating into network of veins); abaxial surface of bladed leaf sheaths smooth (vs. densely papillose); abaxial surface of leaf blades smooth, shiny, and dark green (vs. rough appearing white or dull); and adaxial surface of leaf blades with numerous antrose prickles on surface and veins (vs. no or few prickles on veins).

Carex polymorpha is a member of the section Paniceae. Other members of this section that occur in New York have beakless perigynia except for C. vaginata which occurs in calcareous wetlands (vs. acidic dry to wet habitats) and has proximal bladeless sheaths brown (vs. red brown to purple brown).

Best Time to See

In New York, Carex polymorpha is likely in immature to mature fruit from early June through mid-July and probably into August. The best time to survey for the species is during this time period.

  • Fruiting

The time of year you would expect to find Variable Sedge fruiting in New York.

Variable Sedge Images


Variable Sedge
Carex polymorpha Muhl.

  • Kingdom Plantae
    • Phylum Anthophyta
      • Class Monocotyledoneae (Monocots)
        • Order Cyperales
          • Family Cyperaceae (Sedge Family)

Additional Common Names

  • Sedge

Additional Resources

Best Identification Reference

Rothrock, P.E. and A.A. Reznicek. 2002. Carex Linnaeus sect. Paniceae G. Don. Pages 426-431 in Flora of North America Editorial Committee (editors), Flora of North America, north of Mexico, Volume 23, Magnoliophyta: Commelinidae (in part): Cyperaceae. Oxford University Press, New York, NY, USA. 608pp + xxiv.

Other References

Everett, M. 2001. Carex polymorpha (Variable sedge) Conservation and Research Plan. New England Wild Flower Society, Framingham, Massachusetts, USA (

Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.

Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.

Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.

New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.

New York Natural Heritage Program. 2024. New York Natural Heritage Program Databases. Albany, NY.

Rawinski, T.J. 1988. Final status survey report: The distribution and abundance of variable sedge (Carex polymorpha). Submitted to the U.S. Fish and Wildlife Service, Region 5, Newton Corner, MA. 14 pp.

Rawinski, T.J. 1990. Final status survey report: The distribution and abundance of variable sedge (Carex polymorpha). Unpublished report submitted to U.S. Fish and Wildlife Service, Region 5. Newton Corner, Massachusetts, USA.

Standley, L.A., J.L. Dudley, and L.P. Bruederle. 1991. Electrophoretic variability in the rare sedge, Carex polymorpha (Cyperaceae). Bull. Torrey Botanical Club 118: 444-450.

Standley, L.A., and J.L. Dudley. 1989. Population biology of the globally rare sedge Carex polymorpha. Unpublished report to the Massachusetts Natural Heritage Program, Westborough.

Standley, L.A., and J.L. Dudley. 1991. Vegetative and sexual reproduction in the rare sedge Carex polymorpha (Cyperaceae). Rhodora 93: 268-290.

Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research University of South Florida]. New York Flora Association, Albany, New York


About This Guide

Information for this guide was last updated on: June 22, 2005

Please cite this page as:
New York Natural Heritage Program. 2024. Online Conservation Guide for Carex polymorpha. Available from: Accessed April 16, 2024.