Button Sedge

Carex bullata Schkuhr ex Willd.

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

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


Did you know?

The species name is derived from the Latin "bullatus" which mean inflated and refers to the inflated perigynia of the spike (Fernald 1950). After its discovery in New York in 1894 it was collected many times on Long Island through 1929. There were no subsequent collections for 30 years until Stanley Smith of the NY State Museum collected it again in 1959 after its habitat had been severely reduced by development.

State Ranking Justification

There are four existing populations with substantial numbers of plants. There are 17 populations documented from the late 1800s and early 1900s that have not been resurveyed and eight populations, mainly from western Long Island, that are now considered extirpated.

Short-term Trends

All populations have been visited at least twice and their numbers are stable.

Long-term Trends

About one quarter of the historical populations have been extirpated and this will probably also be true after many of the unsurveyed historical populations have been checked. Many wetlands on Long Island have been destroyed or manipulated to the extent where this species has been reduced in number.

Conservation and Management


One population is threatened by the misuse of herbicides along a railroad right-of-way and another one is threatened by unregulated disturbance by humans. The lack of fire and succession would allow succession of woody plants to shade out the populations.

Conservation Strategies and Management Practices

All populations need to be protected from direct human disturbance and the misuse of herbicides. The immediate habitat needs to be maintained in an early successional stage to prevent the plants from being shaded out by woody plants.

Research Needs

Research is needed to find the best management tool besides fire that can protect and augment populations.



Stream margin within red maple and sedge marsh; wet pine barrens along railroad tracks; wet, muddy banks of stream in a sedge meadow; small groundwater fed sedge meadow/seepage area along the edge of pine barren; coastal plain pond shore; wet successional fields (New York Natural Heritage Program 2010). Acidic soil of bogs and boggy meadows, open swamp forests, peaty or sandy pond and lakeshores, seeps (FNA 2002). Swamps and bogs, chiefly on the coastal plain (Gleason and Cronquist 1991). Acid swales, meadows, and bogs (Fernald 1970).

Associated Ecological Communities

  • Freshwater tidal creek* (guide)
    The aquatic community of a shallow, tidally flooded freshwater creek with submerged areas averaging less than 2 m (6 ft) deep at low tide.
  • Freshwater tidal marsh* (guide)
    A marsh community that occurs in shallow bays, shoals, and at the mouth of tributaries of large tidal river systems, where the water is usually fresh (salinity less than 0.5 ppt), and less than 2 m (6 ft) deep at high tide. Typically there are two zones in a freshwater tidal marsh: a low-elevation area dominated by short, broadleaf emergents bordering mudflats or open water, and a slightly higher-elevation area dominated by tall grass-like plants.
  • Pine barrens vernal pond* (guide)
    A seasonally fluctuating pond and its associated wetlands that typically occurs in pine barrens. The water is intermittent, usually a pond in the spring but sometimes losing water through the summer to become a mostly vegetated wetland at the end of the summer. These ponds and wetlands may be small.
  • Sedge meadow (guide)
    A wet meadow community that has organic soils (muck or fibrous peat). Soils are permanently saturated and seasonally flooded. The dominant herbs must be members of the sedge family, typically of the genus Carex.

* probable association but not confirmed.

Associated Species

  • Acer rubrum
  • Apocynum androsaemifolium (spreading dogbane)
  • Carex barrattii (Barratt's sedge)
  • Carex comosa (bristly sedge)
  • Carex ovalis
  • Carex silicea (beach sedge)
  • Carex stricta (tussock sedge)
  • Carex vestita (velvet sedge)
  • Chamaedaphne calyculata (leatherleaf)
  • Dichanthelium clandestinum (deer-tongue rosette grass)
  • Drosera intermedia (spatulate-leaved sundew)
  • Eleocharis elliptica (elliptic spike-rush)
  • Euthamia graminifolia (common flat-topped-goldenrod)
  • Juncus canadensis (Canada rush)
  • Lechea
  • Lotus corniculatus (common bird's-foot-trefoil)
  • Lycopodiella inundata (northern bog-clubmoss)
  • Mikania scandens (climbing hempweed, climbing boneset)
  • Persicaria sagittata (arrow-leaved tear-thumb)
  • Polygala lutea (orange milkwort)
  • Rhynchospora capitellata (brownish beak sedge)
  • Rosa multiflora (multiflora rose)
  • Rubus hispidus (swamp dewberry)
  • Schoenoplectus americanus (chair-maker's bulrush)
  • Sisyrinchium
  • Sphagnum
  • Toxicodendron vernix (poison-sumac)
  • Triadenum virginicum
  • Viola lanceolata (lance-leaved violet)
  • Viola primulifolia
  • Xyris


New York State Distribution

This sedge is most common on the south side of Long Island, but there are disjunct historical collections from the Hudson Highlands and Central and Western New York.

Global Distribution

Carex bullata ranges mainly along the coastal plain from Maine to Virginia but also found inland in scattered populations from Maine south to Georgia and west to Tennessee Arkansas and Mississippi.

Identification Comments

General Description

Button sedge is a grass-like perennial which grows from long rhizomes. The leaves are 1.8 to 4.3 mm wide, flat or "w-shaped" in cross-section, with purplish-red basal sheaths. The infloresence has 1 to 3 staminate spikes on top, with 1 to 3 lower pistillate spikes, and is subtended by a leafy bract as long or longer than the infloresence. The pistillate scales are awnless and shorter than the fruit (perigynia). The perigynia are 5.9 to 10.2 mm long, scabrous near the tip, contracting into a narrow beak, the beak itself 2.4 to 4.2 mm long and toothed. The perigynia contain 3-sided achenes which are brown, smooth and with 3 stigmas (FNA 2002).

Best Life Stage for Proper Identification

Fruit is needed for a positive identification.

Similar Species

Carex bullata most closely resembles C. michauxiana, C tuckermanii, and C. utriculata. C. utriculata has perigynia with smooth and often shorter beaks (1-2 mm long), and flat or U-shaped leaves. Carex michauxiana has beakless perigynia and leaves with a minutely papillose (bumpy) upper surface. Carex tuckermanii has smooth perigynia and asymmetrical achenes indented on one side. Smooth, flat or W-shaped leaves, scabrous beaks at least 2.4 mm long, and symmetrical perigynia distinguish C. bullata (FNA 2002).

Best Time to See

Carex bullata flowers in May and fruits persist on the plant until the first frost.

  • Fruiting

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

Button Sedge Images


Button Sedge
Carex bullata Schkuhr ex Willd.

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

Additional Common Names

  • Sedge

Additional Resources


Fernald, M. L. 1950. Gray's manual of botany. 8th edition. Corrected printing (1970). D. Van Nostrand Company, New York. 1632 pp.

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.

Gleason, H.A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. New York Botanical Garden, Bronx, New York. 910 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.

Godfrey, R.K., and J.W. Wooten. 1979. Aquatic and wetland plants of southeastern United States: Monocotyledons. Univ. Georgia Press, Athens. 712 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.

Hough, M.Y. 1983. New Jersey wild plants. Harmony Press, Harmony, NJ. 414 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.

Radford, A.E., H.E. Ahles, and C.R. Bell. 1968. Manual of the vascular flora of the Carolinas. Univ. North Carolina Press, Chapel Hill, NC. 1183 pp.

Ridley, H.N. 1930. The dispersal of plants throughout the world. L. Reeve & Co., Ltd., Ashford, Kent, United Kingdom. 744 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 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

Information for this guide was last updated on: September 6, 2012

Please cite this page as:
New York Natural Heritage Program. 2024. Online Conservation Guide for Carex bullata. Available from: https://guides.nynhp.org/button-sedge/. Accessed June 23, 2024.