Eleocharis_tenuis_var._pseudoptera spikelets Richard M. Ring -- Courtesy of the William and
Lynda Steere Herbarium of The New York Botanical Garden

Eleocharis_tenuis_var._pseudoptera spikelets
Richard M. Ring -- Courtesy of the William and Lynda Steere Herbarium of The New York Botanical Garden

Monocotyledoneae (Monocots)
Cyperaceae (Sedge Family)
State Protection
Federal Protection
Not Listed
State Conservation Status Rank
Global Conservation Status Rank


Did you know?

In Quebec this species is known as winged-stem spike-rush because the stems are deeply grooved and thus " falsely winged" (the meaning of pseudoptera) (Flora of North America Editorial Committee 2002).

State Ranking Justification

There are five existing populations, most of them of good quality and in protected areas. There are 12 records from the late 1800s through 1974 that have not been rechecked.

Short-term Trends

Three of the five populations have been rechecked at least once and numbers remain about the same.

Long-term Trends

This plant has always been very rare in New York and populations remain at a low level. Old records have not been rechecked so long-term trends are unclear.

Conservation and Management


Exact threats are unknown at this time.

Conservation Strategies and Management Practices

No management is needed until more study is done of the sites where it occurs.

Research Needs

More survey work is needed to determine the exact range of this species and the habitat it prefers.



There are two New York sites for Slender Spikerush with known habitat information; one is a have been described; one was wet, clayey oldfield, and the other a mowed roadside in a wet pine barrens. More information on the habitat requirements of Slender Spikerush in New York is needed (New York Natural Heritage Program 2010). Wet, fresh, often calcareous meadows, swales, springy places, woods, prairie, serpentine barrens, ditches (FNA 2002). Wet places (Gleason & Cronquist 1991).

Associated Ecological Communities

  • Coastal plain pond shore* (guide)
  • Mowed roadside/pathway
  • Sedge meadow* (guide)
  • Successional old field

Associated Species

  • Artemisia vulgaris (mugwort)
  • Asclepias incarnata
  • Carex bullata (button sedge)
  • Carex silicea (beach sedge)
  • Carx vestita
  • Drosera intermedia (spatulate-leaved sundew)
  • Equisetum arvense (field horsetail, common horsetail)
  • Lotus corniculatus (common bird's-foot-trefoil)
  • Lycopodiella inundata (northern bog-clubmoss)
  • Panicum virgatum (switch grass)
  • Polygala lutea (orange milkwort)
  • Quercus palustris (pin oak)
  • Rhynchospora capitellata (brownish beak sedge)
  • Rubus hispidus (swamp dewberry)
  • Solidago latissimifolia (Elliott's goldenrod)
  • Triadenum virginicum
  • Tripsacum dactyloides
  • Viola lanceolata (lance-leaved violet)
  • Viola primulifolia
  • Xyris


New York State Distribution

This spikerush is currently known from Suffolk County on Long Island and in the Bronx. It has been extirpated from Queens and was also historically known from Lake Carmel in Putnam County.

Global Distribution

This spikerush occurs mostly east of the Mississippi, from Québec and Nova Scotia and south to Georgia in the east, and from Indiana south to Louisiana in the west.

Best Places to See

  • Pelham Bay Park

Identification Comments

General Description

Spikerushes consist of a simple stem (the leaves bladeless and inconspicuous), with the infloresence a solitary, many-scaled spikelet at the top of the stem. The perianth (sepals and petals), if present, is reduced to bristles. The base of the style is expanded into a tubercle, and is usually persistent on the fruit (achenes). Slender Spikerush is a perennial, mat-forming species, growing from rhizomes. Its stems have 4 to 5 sharp angles, and the leaf sheaths are reddish at the base and toothed at the apex. The spikelets are egg-shaped and 3¿6 millimeters long and 1.5 to 2 mmwide. There may be 1 to 3 slender bristles, as long or shorter than the achenes. The achenes are trigonous, yellow, angled, and wrinkled (under 10 -20x magnification) with 10 to 14 depressions in each vertical row. The flower scales persist on the spikelet at least until the achenes fall (FNA 2002).

Best Life Stage for Proper Identification

Mature fruit is necessary for identification.

Similar Species

Eleocharis tenuis var. pseudoptera is also found in New York. It has smooth to bluntly angled stems 0.5 millimeters or less wide, and tubercles as high as they are wide.

Eleocharis elliptica has stems with (4) 6-8 angles, not sharply winged, or sometimes rounded or compressed. the achenes are persistent after the scales fall, and have 12 to 12 horizontal ridges per vertical row (FNA 2002).

Best Time to See

Fruits are present from July through mid-October.

  • Fruiting

The time of year you would expect to find Slender Spike Rush fruiting in New York.

Slender Spike Rush Images


Slender Spike Rush
Eleocharis tenuis var. pseudoptera (Weatherby ex Svens.) Svens.

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


  • Eleocharis elliptica var. pseudoptera (Weatherby ex Svens.) L. Harms

Additional Resources

Best Identification Reference

Flora of North America Editorial Committee. 2002. Flora of North America, North of Mexico. Volume 23. Magnoliophyta: Commelinidae (in part): Cyperaceae. Oxford University Press, New York. 608 pp.

Other References

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.

Mitchell, Richard S. and Gordon C. Tucker. 1997. Revised Checklist of New York State Plants. Contributions to a Flora of New York State. Checklist IV. Bulletin No. 490. New York State Museum. Albany, NY. 400 pp.

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. 2019. New York Natural Heritage Program Databases. Albany, NY.

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 http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://newyork.plantatlas.usf.edu/, Albany, New York


About This Guide

This guide was authored by: Stephen M. Young and Richard M. Ring

Information for this guide was last updated on: January 25, 2012

Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Eleocharis tenuis var. pseudoptera. Available from: https://guides.nynhp.org/slender-spike-rush/. Accessed March 23, 2019.

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