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

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

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


Did you know?

Just a few years ago, this sedge was considered historical within New York (i.e. not seen in at least 20 years). David Werier rediscovered this sedge and he and others have been finding more populations. As more people learn to identify this plant, more populations will likely be encountered.

State Ranking Justification

There are eight existing populations and about 10 historical populations but more of this species are likely to be found in the Hudson Highlands if surveys are done early enough to identify the species before it sheds its perigynia.

Short-term Trends

At least five new populations of this sedge have been located since 2002. Since this sedge is difficult to identify once its fruits shed, fruits relatively early in the season (fruits mostly shed by mid-June), and is easily overlooked, these five new populations were probably overlooked in the past. Therefore, it will probably be hard to determine if this species is expanding its range north as new populations are discovered. Overall, short term trends are not clear.

Long-term Trends

There are 10 populations which have not been seen in recent years. It is unknown if these populations are still extant since searches to many of these sites have not been conducted. In addition, at least five new populations have been seen in recent years. Therefore, long term trends are not clear but most likely the species is at least not declining. This needs to be backed up by further survey work.

Conservation and Management

Research Needs

It has become abundantly clear that this sedge is being overlooked in New York. Survey work in southeastern New York early in the season (May to early June) will help clarify what the abundance of this sedge is in New York.



In New York, C. nigromarginata is found in rocky dry-mesic to mesic deciduous forests. Often these forests are of southern affinity and have oaks dominant. It is also known from coastal oak forests. Less frequently it occurs in more open rocky environments. It prefers S and E facing slopes probably because it is a southern plant at the northern edge of its range (New York Natural Heritage Program 2005). Acidic soils of rocky, dry woods, thickets, and clearings, in partial shade of mixed hardwood-pine forests or full sun along open roadsides and clearing edges, often adjacent to streams (Flora of North America 2002). Dry wooded slopes (Rhoads and Block 2000). Dry woods, chiefly in acid soils on the coastal plain (Gleason and Cronquist 1991). Dry woods, thickets, and clearings (Fernald 1970).

Associated Ecological Communities

  • Acidic talus slope woodland (guide)
  • Allegheny oak forest (guide)
  • Appalachian oak-hickory forest (guide)
  • Appalachian oak-pine forest* (guide)
  • Chestnut oak forest (guide)
  • Cliff community (guide)
  • Coastal oak-beech forest* (guide)
  • Coastal oak-hickory forest (guide)
  • Coastal oak-holly forest (guide)
  • Oak-tulip tree forest* (guide)
  • Successional maritime forest* (guide)
  • Successional shrubland*
  • Successional southern hardwoods*

Associated Species

  • Aristolochia serpentaria
  • Betula lenta (black birch)
  • Carex albicans var. albicans
  • Carex communis
  • Carex digitalis
  • Carex willdenowii (Willdenow's sedge)
  • Carya alba
  • Carya glabra (pignut hickory)
  • Danthonia spicata (poverty grass)
  • Dichanthelium boscii (Bosc's rosette grass)
  • Dichanthelium dichotomum var. dichotomum
  • Lysimachia quadrifolia (whorled-loosestrife)
  • Polygonatum biflorum
  • Quercus alba (white oak)
  • Quercus montana (chestnut oak)
  • Quercus rubra (northern red oak)
  • Quercus velutina (black oak)


New York State Distribution

In New York, populations are known only from the southeastern part of the state; from Long Island north to the southern Hudson Valley (Orange and perhaps Ulster County). A specimen of C. pedunculata from Monroe County was erroneously labeled C. nigromarginata and led to false reports of C. nigromarginata from Monroe County. There is a disjunct population known from Ontario on the northern edge of Lake Ontario (Reznicek and Catling 1982) so Carex nigromarginata should be sought in more southern habitats in other parts of New York.

Global Distribution

A plant typical of the dry woods from Quebec and Ontario south along the Atlantic Coast and west to the Mississippi Valley; possibly disjunct to Saskatchewan.

Best Places to See

  • Wildcat Mountain (Orange County)
  • Schunnemunk Mountain (Orange County)

Identification Comments

General Description

Cusick (1992) describes Carex nigromarginata as "a beautiful sedge with brightly-colored scales of rich chestnut or purple with a green midrib".

The plants are perennial herbs, 4-12 in. tall, growing in dense tufts, often producing short branches which root. The whole plant often has a flattened appearance as if it had been stepped on. Each stem produces a single inflorescence with these flowering stems of varying height. Some of the culms are short and hidden in the leaves while others are longer and more apparent. The principal leaf blades are very narrow (1.4-4.5 mm wide) and mostly arising from the base. The flowers are unisexual. Staminate flowers occur on the end of the elongated flower structure, the pistillate below. Staminate flowers contain three small, slender, erect stamens which project beyond the petals when pollen is produced. There are 1-4 pistillate flowers (usually 2 or 3) up to .25 in. long, stemless, often crowded, and the lowest sometimes slightly separated but overlapping the next above. The small dry fruit does not open at maturity, is three-angled or nearly round, and contains 3 stigmas. The scales that subtend the pistillate flowers/fruits are often dark red to dark purple sub-marginally. These scales also have a green mid-stripe and pale narrow margins (derived from Gleason 1952 and Crins and Rettig 2002).

Identifying Characteristics

Carex nigromarginata has the widest leaves (1.9-)2.2-3.4(-4.5) mm wide. The culms vary in height with the tallest one (measured from the base of the culm to the base of the inflorescence) (4.5) 5.4-17.4 (23.6) mm long. The inflorescence is composed of a terminal staminate spike and 2-3 lateral pistillate spikes, which arise toward the end of the culm (i.e. no basal spikes). All the spikes are approximate. The scales that subtend the pistillate flowers/perigynia are about the same length as the perigynia and usually have a dark-red to dark-purple sub-margin. The actual margin is often white or hyaline in a narrow stripe and the mid vein is green. Occasionally these scales are paler but in most populations most plants have the darker scales. Perigynia are (2.6-)2.8-4.0 mm long with ellipsoid bodies (Crins and Rettig 2002, New York Natural Heritage Program 2005).

Best Life Stage for Proper Identification

This sedge is most easily identified while in fruit. Full ample specimens are useful for identification purposes. These specimens should include the entire plant (i.e. roots, stems, leaves, and fruit).

Similar Species

Carex nigromarginata is a member of section Acrocystis. A few other members of this section are a little similar although C. nigromarginata is really quite a distinctive sedge.

Carex umbellata, C. tonsa var. tonsa, and C. tonsa var. rugosperma should not be confused with C. nigromarginata. The former three all have at least some spikes arising from the base of the culm. These basal spikes can have elongated peduncles and therefore can appear to arise towards the upper parts of the culm. In addition, C. nigromarginata often has some culms that are very short but again these culms have all the spikes arising from the upper portion of the culm.

Carex albicans var. albicans has wider leaves 1.3-2.5(-2.6) mm wide (vs. (1.9-)2.2-3.4(-4.5)mm wide); and most culms are as long as or longer than the leaves (vs. many culms shorter than the leaves). Carex albicans var. emmonsii has the widest leaves (1.4-)1.5-2.5 mm wide; staminate spike peduncle (0.5-)0.7-1.5 mm long (vs. 0.4-0.8 mm long); and perigynia 2.3-3.3 mm (vs. (2.6-)2.8-4.0 mm).

Best Time to See

The species is one of the earliest of the sedges to flower and fruit. It flowers from early April to mid May and is in fruit from late April to early June. The best time to survey for this species is May to very early June.

  • Fruiting

The time of year you would expect to find Black-edge Sedge fruiting in New York.

Black-edge Sedge Images


Black-edge Sedge
Carex nigromarginata Schwein.

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

Additional Common Names

  • Sedge

Comments on the Classification

Some authors included various other members of section Acrocystis as varieties under C. nigromarginata. These include C. nigromarginata var. elliptica (Boott) Gleason = C. peckii; C. nigromarginata var. muhlenbergii (Gray) Gleason = C. albicans var. albicans; C. nigromarginata var. minor (Boott) Gleason = C. albicans var. emmonsii; and C. nigromarginata var. floridana (Schweinitz) K√ľkenthal (which only occurs south of New York) (Gleason 1952, Crins and Rettig 2002). Rettig (1988, 1990) and Rettig and Giannasi (1990) have placed C. nigromarginata in the C. nigromarginata complex comprised of C. nigromarginata, C. floridana, C. albicans var. albicans, C. albicans var. emmonsii, C. albicans var. australis, and C. peckii. In these studies the researchers found C. nigromarginata to be distinct at the species level. Roalson and Friar (2004) found that the C. nigromarginata complex is not monophyletic. Possibilities for the non-monophyly of this complex include cryptic species, hybridization, and gene paralogs.

Additional Resources

Best Identification Reference

Crins, W.J. and J.H. Rettig. 2002. Carex Linnaeus sect. Acrocystis Dumortier. Pages 532-545 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, H.A. 1952. Change of Name for Certain plants on the 'Manual Range.' Phytologia 4(1): 20-25.

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.

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.

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.

Rettig, J.H. 1988. A biosystematic study of the Carex pensylvanica group (section Acrocystis) in North America. Ph.D. dissertation. University of Georgia, Athens.

Rettig, J.H. 1990. Achene micromorphology of the Carex nigromarinata complex (section Acrocystis, Cyperaceae). Rhodora 92: 70-79.

Rettig, J.H. and D.E. Giannasi. 1990. Foliar flavonoids of the Carex nigromarginata complex (section Acrocystis, Cyperaceae). Biochemical Syst. and Ecol. 18: 393-397.

Reznicek, A.A. and P.M. Catling. 1982. Cyperaceae new to Canad from Long Point, Morfolk County. Can. Field Nat. 96: 184-188.

Rhoads, Ann F. and Timothy A. Block. 2000. The Plants of Pennsylvania, an Illustrated Manual. University of Pennsylvania Press, Philadelphia, PA.

Roalson, E.H. and E.A. Friar. 2004. Phylogenetic relationships and biogeographic patterns in North American members of Carex section Acrocystis (Cyperaceae) using nrDNA its and ETs sequence data. Plant Systematics and Evolution 243: 175-187

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. 2019. Online Conservation Guide for Carex nigromarginata. Available from: Accessed March 25, 2019.

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