Slender Spike Grass

Chasmanthium laxum (L.) Yates

Chasmanthium laxum illustration

Monocotyledoneae (Monocots)
Poaceae (Grass 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 - Common in the world; widespread and abundant (but may be rare in some parts of its range).


Did you know?

This grass had only been collected a few times in New York before the last collection in September of 1936 from Valley Stream on Long Island. Then in 1996, exactly 60 years later to the month, it was rediscovered in Eastern Long Island during a natural community inventory by New York Natural Heritage botanists Greg Edinger and David Hunt. Their discovery is still the only known occurrence in the state.

State Ranking Justification

There is one existing population which was discovered in 1996. There are two historical populations known from the 1800s and early 1900s which have been surveyed but no plants were found. Three additional populations from western Long Island are considered extirpated.

Short-term Trends

The only existing population has been surveyed only once so short-term trends are unknown.

Long-term Trends

This plant was always very rare in New York but none of the old records have been rediscovered and only two small clumps presently survive.

Conservation and Management


The incursion of Phragmites into this plant's wetland habitat is a threat as well as the direct disturbance of the wetlands through ditching.

Conservation Strategies and Management Practices

The population needs to be protected from direct disturbance and from the invasion of Phragmites.

Research Needs

Research is needed on how to augment and protect the existing population.



The only extant population of Chasmanthium laxum in New York was found in an intact Red Maple-Black Gum swamp, though historically the species has also been reported from bogs (New York Natural Heritage Program 2010). Moist sandy soils of the coastal plain (Rhoads and Block 2000). Woods, meadows and swamps (Fernald 1970).

Associated Ecological Communities

  • 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.
  • Red maple-blackgum swamp (guide)
    A maritime, coastal, or inland hardwood swamp that occurs in poorly drained depressions, sometimes in a narrow band between a stream and upland. Red maple and blackgum are often codominant or blackgum may be the dominant tree. Pitch pine may occur on drier hummock islands in pine barrens settings.

* probable association but not confirmed.

Associated Species

  • Acer rubrum
  • Carex folliculata (long sedge)
  • Nyssa sylvatica (black-gum, sour-gum)
  • Vaccinium corymbosum (highbush blueberry)


New York State Distribution

This grass is currently known from Suffolk County on eastern Long Island and considered extirpated from western Long Island and Staten Island.

Global Distribution

This grass ranges from Long Island to New Jersey and eastern Pennsylvania south through the eastern states to Florida and west through Virginia, Kentucky, Missouri, and Arkansas to Eastern Texas.

Identification Comments

General Description

Dune Sandspur is a perennial grass species with unbranched stems 40 to 130 cm tall. The leaves extend halfway up the stem, and are glabrous with blades 15-35 cm long and 3-8 mm wide. The spikelets disarticulate below the glumes, and are strongly laterally compressed (keeled), 5 to 8 mm long and 2 to 6 mm wide, each with 3 to 5 flowers, the bottom 1 or 2 sterile (FNA 2003, Gleason and Cronquist 1991).

Best Life Stage for Proper Identification

Specimens with mature fruit are needed for identification.

Similar Species

Slender Spikegrass is the only species of its genus native to New York, and its laterally compressed spikelets on unbranched stems are distinctive. Chasmanthium latifolium, with broader leaves and larger, drooping spikelets, is sometimes planted as an ornamental species.

Best Time to See

Slender Spikegrass flowers from mid-June to mid-September, mature fruits persist to mid-October.

  • Flowering
  • Fruiting

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

Slender Spike Grass Images


Slender Spike Grass
Chasmanthium laxum (L.) Yates

  • Kingdom Plantae
    • Phylum Anthophyta
      • Class Monocotyledoneae (Monocots)
        • Order Cyperales
          • Family Poaceae (Grass Family)


  • Uniola laxa (L.) B.S.P.

Additional Resources

Best Identification Reference

Flora of North America Editorial Committee. 2003. Flora of North America, North of Mexico. Volume 25. Magnoliophyta: Commelinidae (in part): Poaceae, part 2. Oxford University Press, New York. 783 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. 2024. New York Natural Heritage Program Databases. Albany, NY.

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.

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

This guide was authored by: Stephen M. Young

Information for this guide was last updated on: September 20, 2012

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