Canadian Single-spike Sedge

Carex scirpoidea ssp. scirpoidea None

Carex scirpoidea
Stephen M. Young

Monocotyledoneae (Monocots)
Cyperaceae (Sedge Family)
State Protection
Listed as Endangered by New York State: in imminent danger of extirpation in New York. For animals, taking, importation, transportation, or possession is prohibited, except under license or permit. For plants, removal or damage without the consent of the landowner is prohibited.
Federal Protection
Not Listed
State Conservation Status Rank
Critically Imperiled in New York - Especially vulnerable to disappearing from New York due to extreme rarity or other factors; typically 5 or fewer populations or locations in New York, very few individuals, very restricted range, very few remaining acres (or miles of stream), and/or very steep declines.
Global Conservation Status Rank
Secure globally - Both the species as a whole and the subspecies/variety are common in the world; widespread and abundant (but may be rare in some parts of its range).


Did you know?

The specific epithet scirpoidea means like Scirpus, which is a different genus of sedges. It is unclear what member of the genus Scirpus, Carex scirpoidea resembles. Some members of the genera Eleocharis and Trichophurm which have at times been placed in the genus Scirpus, have a superficial similarity to Carex scirpoidea.

State Ranking Justification

There are six known populations, but two are quite small. Most of these populations are subject to various types of recreational impacts, but mainly trampling from hikers. There are only two historical sites that need further follow-up with additional habitat elsewhere within the Adirondacks. Within eastern North America, New York is this species' southern limit.

Short-term Trends

No populations appear to have been extirpated in the recent past but precise trends are unclear. In some cases, the populations are very small and therefore, probably have declined. It is unclear if this decline is in recent years.

Long-term Trends

This is one of those plants that has likely been rare for many decades. Therea were only two populations known in the early 1900s. These populations have not been surveyed recently and may still be extant. Most of the extant populations have been known for at least 50 years. Some of these are quite small, are restricted to alpine areas, and may be declining. The decline of these local populations may be due to a variety of factors including recreational activities and climate change.

Conservation and Management


There are some populations which are being negatively impacted by rock climbing and trampling. Some populations are in alpine or cool northern environments. These populations are potentially threatened by a warming climate.

Conservation Strategies and Management Practices

The stewardship summit program involves having stewards on the Adirondack high peak summits. These stewards facilitate the protection of fragile summit ecosystems and their flora through education. This program should be continued. Some populations need to be protected from rock climbing activities. This can be accomplished through education and where needed restricting access to vulnerable sites.

Research Needs

Surveys of sites only known by historical records should be conducted. For sites where populations are small, surveys should carefully note the area of the population as well as the number of plants present.



This species occurs on calcareous, wet or seepy cliffs and ledges; thin soil over rocks in alpine meadows; and openings in rich forests on thin soils over calcareous rocks (New York Natural Heritage Program 2006). Calcareous soils (Dunlop 2002). Wet rocks, shores, and meadows in alpine and subalpine areas (Haines and Vining 1998). Dry soil, especially in calcareous regions (Gleason and Cronquist 1991). Crevices and thin soil over rock and gravelly calcareous shores, in areas at least seasonally damp (Voss 1972).

Associated Ecological Communities

  • Alpine krummholz (guide)
    A dwarf woodland dominated by balsam fir that occurs at or near the summits of the high peaks of the Adirondacks.
  • Calcareous cliff community (guide)
    A community that occurs on vertical exposures of resistant, calcareous bedrock (such as limestone or dolomite) or consolidated material; these cliffs often include ledges and small areas of talus.
  • Calcareous talus slope woodland* (guide)
    An open or closed canopy community that occurs on talus slopes composed of calcareous bedrock such as limestone or dolomite. The soils are usually moist and loamy; there may be numerous rock outcrops.
  • Northern white cedar rocky summit (guide)
    A community that occurs on cool, dry, rocky ridgetops and summits where the bedrock is calcareous (such as limestone or dolomite), and the soils are more or less calcareous. The vegetation may be sparse or patchy, with numerous rock outcrops. The species have predominantly boreal distributions.

* probable association but not confirmed.

Associated Species

  • Carex eburnea (bristle-leaved sedge)
  • Dasiphora floribunda
  • Oligoneuron album
  • Panicum flexile (wiry witch grass)
  • Prenanthes trifoliolata
  • Trisetum spicatum (narrow oat grass)


New York State Distribution

This sedge is at the southern edge of its range in New York. It is known from a few scattered locations in the Adirondack high peaks and from two populations just south of Lake Champlain.

Global Distribution

Carex scirpoidea ssp. scirpoidea is a wide ranging taxon occuring in North America, Europe, and eastern Asia. In North America it occurs from Alaska, Nunavut, and Greenland south to Nova Scotia, New Hampshire, Vermont, New York, Michigan, Minnesota, North Dakota, Colorado, Utah, Nevada, and Oregon (Dunlop 2002).

Identification Comments

General Description

Carex scirpoidea ssp. scirpoidea is a tufted grass-like plant. Leaves are strap-like and 2.5 mm wide. Stems are 5-40 cm tall and have one flower/fruit cluster (spike) at their apices. Spikes are composed of either entirely male or entirely female flowers and are narrowly cylindrical. Stems from individual plants usually have only male spikes or only female spikes. Female flowers develop into fruits (perigynia) which are 1.8-3 mm long (Dunlop 2002).

Identifying Characteristics

Carex scirpoidea ssp. scirpoidea is a cespitose, dioecious, perennial. Culms are 5-35(-40) cm long and are equal to or exceed the leaves. Lower leaf sheaths are bladeless and purplish. Leaf blades are up to 2.5 mm wide. Bracts are leaf-like to rarely scale like. Spikes are solitary and linear-cylindric. The pistillate spikes are 1.0-4.0 cm long and the staminate are 1.0-2.0 cm long. Pistillate scales are red-brown to purple and the perigynia are (1.8-)2.0-2.5(-3.0) mm long (Robertson 1984, Dunlop 2002).

Best Life Stage for Proper Identification

This species is easiest to identify when it is in flower or fruit.

Similar Species

Carex scirpoidea ssp. scirpoidea is a very distinctive Carex and should not be confused with other species. This species can be separated from all other Carex species by its unisexual habit, single spiked culms, pistillate spikes up to 4.0 cm long, and non-involute leaves (Gleason and Cronquist 1991, Dunlop 2002). Carex scirpoidea ssp. convoluta may occur in the alvar regions of New York. It can be distinguished by its pistillate culm leaves narrowly V-shaped and less than 1.5 mm wide vs. pistillate culm leaves widely V-shaped and greater than 1.5 mm wide for ssp. scirpoidea (Dunlop 2002).

Best Time to See

Elevational differences should be taken into account when assessing when to survey for this species. This species is in flower or fruit from May till early September depending on elevation. Towards the end of this season the perigynia may be shedding and the spikes are a little less obvious. Therefore, the best time to survey for this species is between June and August. Although, the earlier part of this time period may not be appropriate for higher elevation populations.

  • Fruiting

The time of year you would expect to find Canadian Single-spike Sedge fruiting in New York.

Canadian Single-spike Sedge Images


Canadian Single-spike Sedge
Carex scirpoidea ssp. scirpoidea None

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

Additional Common Names

  • Sedge

Comments on the Classification

A few taxa that were previously recognized as species or varieties are treated by Dunlop (2002) as subspecies of Carex scirpoidea. Still, there is only one taxon known from New York and most of the east. This is recognized as C. scirpoidea ssp. scirpoidea. The only other taxon known from the east, C. scirpoidea ssp. convoluta, is an endemic of alvar in Michigan and Ontario (Dunlop 2002). Carex scirpoidea ssp. convoluta is a characteristic member of the "little bluestem alvar grassland" community (Reschke et al. 1999). Reschke et al. (1999) reports a small amount of this community type from New York but no C. scirpoidea ssp. convoluta has been documented from NY. Carex scirpoidea is a member of section Scirpinae which has only three species and of these only C. scirpoidea occurs in eastern North America (Dunlop 2002).

Additional Resources

Best Identification Reference

Dunlop, D.A. 2002. Carex Linnaeus sect. Scirpinae (Tuckerman) Kükenthal. Pages 549-553 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, New York, USA. 608pp + xxiv.

Other References

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.

Haines, A. and T.F. Vining. 1998. Flora of Maine, A Manual for Identification of Native and Naturalized Vascular Plants of Maine. V.F.Thomas Co., Bar Harbor, Maine.

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.

Reschke, C., R. Reid, J. Jones, T. Feeney, and H. Potter. 1999. Conserving Great Lakes Alvars: final technical report of the International Alvar Conservation Initiative. The Nature Conservancy, Great Lakes Program, Chicago, IL.

Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.

Robertson, A. 1984. Carex of Newfoundland. Newfoundland Forest Research Centre, St. John, Newfoundland, Canada.

Voss, E.G. 1972. Michigan Flora, Part I. Gymnosperms and Monocots. Cranbrook Institute of Science Bulletin 55 and the University of Michigan Herbarium. Ann Arbor. 488 pp.

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: May 31, 2006

Please cite this page as:
New York Natural Heritage Program. 2024. Online Conservation Guide for Carex scirpoidea ssp. scirpoidea. Available from: Accessed July 19, 2024.