Troublesome Sedge

Carex molesta Mackenzie ex Bright

Robert H. Mohlenbrock. Downloaded from USDA Plants Database.

Monocotyledoneae (Monocots)
Cyperaceae (Sedge Family)
State Protection
Listed as Threatened by New York State: likely to become Endangered in the foreseeable future. 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
Apparently Secure in New York - Uncommon in New York but not rare; usually widespread, but may be rare in some parts of the state; possibly some cause for long-term concern due to declines or other factors.
Global Conservation Status Rank
Apparently Secure globally - Uncommon in the world but not rare; usually widespread, but may be rare in some parts of its range; possibly some cause for long-term concern due to declines or other factors.


Did you know?

The specific epithet molesta means troublesome (Fernald 1970). This species is part of a group of closely related plants that have proven difficult to understand with three new species being described from central United States since 1997.

State Ranking Justification

There are 13 known populations and approximately 20 historical locations. This is a Section Ovales sedge that is likely overlooked. It has a broad habitat requirements, although it may prefer calcareous or circum-nuetral soils. Some of the alvar populations are very large, although this habitat has been threatened by development, succession, and invasive species.

Short-term Trends

There are about a dozen populations that have been seen in recent years. No data is available about trends at these sites. The full extent of most of these populations is not known. Four populations are fairly large and healthy. A few populations are relatively small. Overall short term trends are not clear.

Long-term Trends

There are 20 to 40 populations which are only known from historical records. Almost all of these populations have not been searched for recently and it is unknown if they are still extant. This is a somewhat weedy species that likes open fields and native grasslands. It is probably more common than records indicate. As fields undergo succession in New York State this plant may decline but perhaps only back to historical levels. Overall, long term trends are not clear.

Conservation and Management


Potential threats include grazing, invasive species, ATV traffic, and shading due to succession of habitat.

Conservation Strategies and Management Practices

Invasive species need to be monitored and controlled at some populations. ATV use needs to be restricted to trails. Habitats that stay open due to fire should be maintained as open habitats by controlled burns or by other means.

Research Needs

Surveys to historical sites are needed. In addition, surveys should be conducted to likely habitat such as fields in areas with limestone bedrock.



Carex molesta most commonly occurs in fields, wet fields, and native grasslands such as alvar grasslands and oak openings. It also occurs less frequently on open edges of rivers, woodlands, talus slopes, and in waste areas. It prefers strongly calcareous soils that are dry to wet (New York Natural Heritage Program 2006). Often somewhat weedy. Fields, roadsides, bottomlands, open woods, on dry to wet, often heavy, calcareous soils (Mastrogiuseppe et al. 2002). Dry or slightly moist open grounds, borders of woods, etc. (Fernald 1970). Dry woodlands (Mackenzie 1931-1935).

Associated Ecological Communities

  • Alvar pavement grassland (guide)
    This community consists of exposed, flat limestone or dolostone pavement with grassy or mossy patches interspersed throughout. Some examples may be solely grassland with no pavement.
  • Alvar woodland* (guide)
    A subset of the limestone woodland community restricted to the alvar region in Jefferson County, New York.
  • 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.
  • Inland calcareous lake shore (guide)
    The gravelly, sandy, or muddy shore of an inland lake or pond with calcareous water and seasonally fluctuating water levels. There may be few plants and those that are present are usually herbaceous.
  • Limestone woodland* (guide)
    A woodland that occurs on shallow soils over limestone bedrock in non-alvar settings, and usually includes numerous rock outcrops. There are usually several codominant trees, although one species may become dominant in any one stand.
  • Oak openings (guide)
    A grass-savanna community that occurs on well-drained soils. In New York, these savannas originally occurred as openings within extensive oak-hickory forests. The best remnants occur on dolomite knobs.
  • Successional old field
    A meadow dominated by forbs and grasses that occurs on sites that have been cleared and plowed (for farming or development), and then abandoned or only occasionally mowed.
  • Successional shrubland*
    A shrubland that occurs on sites that have been cleared (for farming, logging, development, etc.) or otherwise disturbed. This community has at least 50% cover of shrubs.

* probable association but not confirmed.

Associated Species

  • Allium schoenoprasum (chives)
  • Boechera laevigata
  • Bromus kalmii (Kalm's brome)
  • Carex crawei (Crawe's sedge)
  • Cornus racemosa (gray dogwood, red-panicled dogwood)
  • Deschampsia cespitosa (tufted hair grass)
  • Eleocharis compressa
  • Packera paupercula (balsam groundsel)
  • Sorghastrum nutans (Indian grass)
  • Thuja occidentalis (northern white cedar, arbor vitae)


New York State Distribution

Carex molesta is known from widely scattered populations throughout most of New York excluding the Adirondacks and Catskills.

Global Distribution

Carex molesta occurs from Quebec,west to New York, Ontario, Minnesota, and North Dakota south to Oklahoma, Arkansas, Mississippi, Alabama, and Virginia. It is also naturalized in California (Mastrogiuseppe et al. 2002).

Identification Comments

General Description

Troublesome sedge is a tufted grass-like perennial. Leaves are strap-like and 1.5-4.0 mm wide. As with other species in section Ovales, troublesome sedge has some stems with flower/fruit clusters (reproductive stems) and some stems without these structures (vegetative stems). The reproductive stems are 35-110 cm tall and have 3-6 leaves attached to the lower portion of the stems. At the apex of the reproductive stems are 2-5 tightly arranged, stalkless, round flower/fruit clusters (spikes). The upper flowers in the spikes are female and the lower male. The female flowers develop into fruits (perigynia) which are 3.0-5.7 mm long and flat (Mackenzie 1931-1935, Mastrogiuseppe 2002).

Identifying Characteristics

Carex molesta is cespitose and short rhizomatous. Leaf sheaths are adaxially green and have a narrow hyaline summit. Leaf blades are 1.5-4.0 mm wide. Reproductive culms are 35-110 mm long and exceed the leaves. The inflorescences are 1.3-3.0(-3.5) mm long and are composed of 2-4(-5) approximate gynecandrous spikes. The spikes are globose to ellipsoid and are rounded at the base and apex. Pistillate scales are hyaline-brown and are shorter than the perigynia they subtend. Perigynia spread at maturity, have 5+ conspicuous veins abaxially, 0-6 conspicuous veins adaxially, are elliptic to almost orbiculate, and 1.8-3.0 mm wide. Beaks are 0.7-1.6(-1.8) mm wide (Mackenzie 1931-1935, Mastrogiuseppe et al. 2002).

Best Life Stage for Proper Identification

It is easiest to identify C. molesta when it has almost mature to mature perigynia. The whole plant is helpful in identification and should be collected.

Similar Species

Carex molesta is most similar to C. brevior and is also closely related to C. festucacea. Carex brevior can be distinguished by the more numerous spikes [(3-)4-7], more open inflorescences [proximal internodes (3-)6-13(-23) mm long], and less perigynia per spike [(10-)15-40(-45)]. In comparison, C. molesta has less spikes [2-4(-5)], more congested inflorescences [proximal internodes 1.5-6.0 mm long], and more perigynia per spike [(25-)30-80].

Carex festucacea has spikes acute to acuminate at the bases and terminal spikes with conspicuous staminate bases. In comparison, C. molesta has spikes rounded at the bases and terminal spikes without conspicuous staminate bases.

Carex bicknellii and C. merritt-fernaldii are perhaps also somewhat similar. They differ in having very thin wafer-like perigynia and papillose leaf sheaths. In comparison, C. molesta has thicker more coriaceous perigynia and smooth leaf sheaths.

Best Time to See

Carex molesta starts to produce immature perigynia in June. These mature and persist into early August or sometimes later. During the later part of this season the perigynia are shedding easily. Therefore the best time to survey for this species is from June through July.

  • Fruiting

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

Troublesome Sedge Images


Troublesome Sedge
Carex molesta Mackenzie ex Bright

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

Additional Common Names

  • Sedge

Comments on the Classification

Carex molesta is in section Ovales. It is also in the informal Carex brevior group which in New York includes C. bicknellii, C. merritt-fernaldii, C. festucacea, and C. brevior (Rothrock and Reznicek 2001). Its closest allies in New York are C. festucacea and C. brevior. Other similar species such as C. molestiformis do not occur close to New York (Reznicek and Rothrock 1997). Carex molesta was lumped under C. brevior by Gleason and Cronquist (1991) but the two are distinct (Reznicek and Rothrock 1997).

Additional Resources

Best Identification Reference

Mastrogiuseppe, J., P.E. Rothrock, A.C. Dibble, and A.A. Reznicek. 2002. Carex Linnaeus sect. Ovales Kunth. Pages 332-378 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

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.

Mackenzie, K.K. 1931-1935. Cariceae. North American Flora 18: 1-478.

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.

Reznicek, A.A. and P.E. Rothrock. 1997. Carex molestiformis (Cyperaceae), a new species of section Ovales from the Ozark Mountain region. Contr. Univ. Michigan Herb. 21: 299-308.

Rothrock, P.E. and A.A. Reznicek. 2001. The taxonomy of the Carex bicknellii group (Cyperaceae) and new species for central North America. Novon 11:205-228.

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: January 14, 2009

Please cite this page as:
New York Natural Heritage Program. 2024. Online Conservation Guide for Carex molesta. Available from: Accessed April 17, 2024.