Carex polymorpha - Muhl.
Variable Sedge
Other Common Names: variable sedge
Taxonomic Status: Accepted
Related ITIS Name(s): Carex polymorpha Muhl. (TSN 39765)
Unique Identifier: ELEMENT_GLOBAL.2.128460
Element Code: PMCYP03AW0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Sedge Family
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Cyperales Cyperaceae Carex
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Concept Reference
Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Carex polymorpha
Conservation Status

NatureServe Status

Global Status: G3
Global Status Last Reviewed: 04Nov1997
Global Status Last Changed: 14Nov1997
Rounded Global Status: G3 - Vulnerable
Reasons: Most of this species' habitat has been developed or mined for sand, gravel, and topsoil. Loss of habitat has probably eliminated it from three of its historic twelve-state range; four states have only one surviving population each. In total, about thirty occurrences are known extant, and most of these remain severely threatened. Most of a large, healthy population in West Virginia is protected on a Nature Conservancy preserve.
Nation: United States
National Status: N3

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Connecticut (S1), Delaware (SX), Maine (S1), Maryland (SH), Massachusetts (S2), New Hampshire (S1), New Jersey (S1), New York (SX), Pennsylvania (S2), Rhode Island (S1), Virginia (S2), West Virginia (S1)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Extant in Connecticut, Massachusetts, Maine, New Hampshire, New Jersey, Pennsylvania, Rhodes Island, Virginia, and West Virginia. Historical records from Delaware, Maryland, New York. Some states with only one population.

Number of Occurrences: 21 - 80
Number of Occurrences Comments: Approximately thirty occurrences altogether: Connecticut-one; Massachusetts-one; Maine-five; New Hampshire-one; New Jersey-two; Pennsylvania-seven; Rhode Island-one; Virginia seven-ten; West Virginia-five.

Population Size Comments: Population size varies from one to several individuals at a site to 1000+ individuals at a site.

Overall Threat Impact Comments: Very threatened in New England; Populations in West Virginia are under little imminent threat at The Nature Conservancy preserve on Panther Knob, yet seemingly remote rugged sites can be bulldozed and developed almost overnight. All sites, except preserve, are susceptible to recreational development for vacation homes on ridge tops.

Much destruction of Carex polymorpha habitat has occurred and continues to occur throughout its range. In states where it formerly occurred, many historic localities have been destroyed by sand and gravel mining and residential development. The historic station at Bride Brook, CT., when field checked by T. Rawinski on June 28, 1986, had in large part been supplanted by a mile-long gravel pit. Historic collection sites from large cities such as Manchester, NH and Providence, RI, and the now heavily urbanized Queens Co., NY. are presumed destroyed. In Pennsylvania, many acres of suitable habitat have been stripped for top-soil. Within the past year, new houses have encroached upon two Maine populations, including the state's largest. Threats to potential Carex polymorpha habitats in southeastern Massachusetts include tremendous pressures to develop lowland areas for cranberry production. Part of the Kyle Knob, WV. population (elevation 4,000 to 4,600 feet) has recently been lost to vacation home development, and the remaining plants are in jeopardy.

Short-term Trend: Decline of 10-30%
Short-term Trend Comments: Declining or extirpated in all states except, perhaps, Virginia and West Virginia. Loss of habitat has probably eliminated it from three of its historic twelve-state range.

Intrinsic Vulnerability Comments: May require some disturbance to habitat to prevent succession to woody vegetation.

Other NatureServe Conservation Status Information

Global Range: Extant in Connecticut, Massachusetts, Maine, New Hampshire, New Jersey, Pennsylvania, Rhodes Island, Virginia, and West Virginia. Historical records from Delaware, Maryland, New York. Some states with only one population.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States CT, DEextirpated, MA, MD, ME, NH, NJ, NYextirpated, PA, RI, VA, WV

Range Map
No map available.

U.S. Distribution by County Help
State County Name (FIPS Code)
CT Middlesex (09007), New Haven (09009), New London (09011)*, Tolland (09013), Windham (09015)
MA Berkshire (25003)*, Bristol (25005)*, Hampden (25013)*, Middlesex (25017), Norfolk (25021)*, Plymouth (25023), Worcester (25027)
MD Cecil (24015)*
ME Cumberland (23005), York (23031)*
NH Hillsborough (33011)*, Merrimack (33013)*, Rockingham (33015)*, Strafford (33017)
NJ Gloucester (34015)*, Middlesex (34023)*, Monmouth (34025)*, Morris (34027), Somerset (34035)*, Union (34039)*, Warren (34041)*
NY Nassau (36059)*, Queens (36081)*, Suffolk (36103)*
PA Carbon (42025), Chester (42029)*, Cumberland (42041), Delaware (42045)*, Lancaster (42071)*, Luzerne (42079), Monroe (42089), Northampton (42095)
RI Bristol (44001)*, Kent (44003), Providence (44007)
VA Alleghany (51005), Amherst (51009), Augusta (51015), Bath (51017), Highland (51091), Rappahannock (51157), Rockingham (51165)
WV Pendleton (54071)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Presumpscot (01060001)+, Piscataqua-Salmon Falls (01060003)+, Merrimack (01070006)+*, Chicopee (01080204)+, Lower Connecticut (01080205)+, Charles (01090001)+, Cape Cod (01090002)+, Blackstone (01090003)+, Narragansett (01090004)+*, Pawcatuck-Wood (01090005)+, Quinebaug (01100001)+, Shetucket (01100002)+, Thames (01100003)+*, Quinnipiac (01100004)+, Housatonic (01100005)+
02 Hackensack-Passaic (02030103)+*, Sandy Hook-Staten Island (02030104)+*, Raritan (02030105)+, Southern Long Island (02030202)+*, Long Island Sound (02030203)+*, Middle Delaware-Mongaup-Brodhead (02040104)+, Middle Delaware-Musconetcong (02040105)+, Lehigh (02040106)+, Lower Delaware (02040202)+*, Brandywine-Christina (02040205)+*, Mullica-Toms (02040301)+*, Upper Susquehanna-Lackawanna (02050107)+, Lower Susquehanna-Swatara (02050305)+, Lower Susquehanna (02050306)+*, Chester-Sassafras (02060002)+*, South Branch Potomac (02070001)+, Conococheague-Opequon (02070004)+, South Fork Shenandoah (02070005)+, Rapidan-Upper Rappahannock (02080103)+, Upper James (02080201)+, Maury (02080202)+, Middle James-Buffalo (02080203)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Basic Description: A stout-stemmed (2-6 dm tall), strongly rhizomatous, perennial sedge.
General Description: This sedge is an herbaceous grass-like perennial herb. Reproductive shoots are up to 60 cm tall. Leaf width is 2.5-5.0 mm wide. It spreads vegetatively by elongate rhizomes with one or a few shoots arising from nodes along the rhizomes.
Technical Description: Carex polymorpha is a distinctive sedge locally distributed from Maine to Virginia (Figure l). Within the genus Carex, C. polymorpha is placed in the Paniceae species-group with the European Carex panicea, and native eastern North American species, Carex livida, Carex tetanica, Carex woodii, Carex meadii, and Carex vaginata (Fernald 1950). Like all members of the Paniceae, C. polymorpha has 1) a strongly rhizomatous growth form; 2) bracts with well-developed sheaths; 3) purple-brown or red-brown pistillate scales; 4) ovoid to obovoid perigynia which are green, glabrous, and inflated. Among the Paniceae, C. polymorpha is distinguished by its long perigynium beak with oblique orifice, rhizomes and stolons which are hard and stout, and three or more rows of perigynia in the spikes.

Additional field characters useful in recognizing C. polymorpha are leaves that are pastel-green in early summer and tawny-yellow by October, polymorphic reproductive culms which can bear three, two, one or no pistillate spikes, and overwintering perennating shoots whose summits bend, rather than stab, under gentle finger pressure. Standley and Dudley (1989) provide the following technical description: "Plants rhizomatous, the shoots annual, lacking old leaves at the base. Vegetative shoots to 40 cm tall, blades 2.5-5.0 mm wide, glaucous when young and yellow-green later in season, plicate, the sheaths all with blades, glabrous, red on dorsal surface, the inner band wide, membranous, faintly veined, white or pale brown. Flowering shoots to 60 cm high, the culms triangular with acute, scabrous angles, with 3-4 leaves, the leaves 10-15 cm long, shorter than the inflorescence, 2.5-5.0 mm wide, all sheaths with blades, red dorsally glabrous. The basal scale leaves red-brown or purple-brown, not disintegrating to form a pinnate network of persistent veins. Bracts foliaceous, shorter than the inflorescence, sheathing. Inflorescence with 2-5 erect spikes. Terminal 1 (2) spikes staminate, long-peduncled, purple-brown. Lower 1-2(3) spikes pistillate (occasional culms with no pistillate spikes), cylindric, generally staminate at apex and frequently proliferating and branching at base, 1.5-3.5 cm x 7.5-10.0 mm, peduncled. Pistillate scales ovate, acute, purple-brown with conspicuous green center, shorter and narrower than the perigynium. Perigynia 4-5.5 x 2.5 mm, spreading, the body inflated, orbicular, 2-keeled, glabrous, olive-green, abruptly contracted into slender beak 1.5-2.0 mm long, the apex oblique, entire, hyaline. Achenes obovoid, 2.5 x 2 mm, dark brown, sessile, the style deciduous."

Diagnostic Characteristics: Carex polymorpha bears a close resemblance in vegetative form to the unrelated C. vestita, with which it often grows. Standley and Dudley (1989) have prepared a summary of vegetative characters of Carex polymorpha and C. vestita: CHARACTERS: Length of bladeless sheath leaves 8-10 cm (C. VESTITA)vs. 5 cm (C. POLYMORPHA). Apex of bladeless sheath Sharply acute (C. VESTITA) vs. Broadly acute Leaves (C. POLYMORPHA). Bladeless sheath leaves with persistent network of veins (C. VESTITA only). Foliage leaf, abaxial surface Smooth, shiny, dark green(C. VESTITA) vs. Densely papillose, rough, appearing white or dull (C. POLYMORPHA). Foliage leaf blade, adaxial surface scabrous, numerous antrorse prickles on surface and veins (C. VESTITA) vs. smooth, no prickles (or few on veins) (C. POLYMORPHA).
Ecology Comments: A population biology study of Carex polymorpha was completed in 1989 by Standley and Dudley. The results of their work is summarized here.


Weekly visits conducted on populations in Massachusetts and Maine during May, 1988 revealed that Carex polymorpha is protogynous: the pistillate phase lasts less than one week, followed by a brief hermaphroditic phase (one to two days), concluded by a staminate phase of one to several days. Some self-pollination does occur during the period of overlap. Asynchrony in flowering was noted to occur within and among populations. Achene maturation had occurred by the second week in July in both the Maine and Massachusetts populations studied.


Potential fecundity of Carex polymorpha is limited at several stages of sexual reproduction: 1) production of flowering shoots, 2) production of pistillate spikes and perigynia, and 3) fruit set. Proportions of flowering shoots, pistillate spikes, and perigynia are related to degree of canopy closure. Shoot production was found to be 1.5% in open canopy, and < 1% (or absent) in closed canopy sites at the Maine borrow pit; spike production per culm ranged from 1 to 2 with 16-40 perigynia. Seed set varied substantially between shaded and unshaded sites, ranging from fewer than 2 achenes per spike (10%) to 30 achenes per spike (72%). Controlled pollination experiments (emasculation, bagging, or hand-pollination) confirmed that C. polymorpha is self-compatible; when compared with Carex vestita, C. polymorpha was found to have higher actual fecundity. So although the rate of sexual reproduction in C. polymorpha is low, it is not lower than that of a more common species of the genus. Thus low sexual reproduction may not be a major cause for the species' rarity.

Patterns of rhizome and shoot growth were studied in the Maine borrow pit populations to determine whether canopy conditions affect vegetative growth. Rhizome length, weight, and leaf width were found to be lower in shaded conditions, suggesting that resource limitation does hamper vegetative growth in the shade. Sympodial growth form of rhizomes produces long-lived large populations of rhizomes which produce relatively few new genets, but which can transfer nutrients among ramets and even out patchy distribution of resources in shaded situations. Shoot growth exhibits a pattern in which shoots persist for only a single growing season, are produced rapidly and continuously with high turnover, allowing colonization of available microsites. These vegetative growth patterns are similar to those of other species of Carex.


Gel electrophoresis was conducted on leaf tissue of Carex polymorpha from populations at the Maine borrow pit and woods sites, as well as those in Massachusetts and Pennsylvania. Relatively high genetic diversity was exhibited within some populations; diversity among populations was not correlated with geographic proximity. For example, the Maine borrow pit population was more similar to that of Pennsylvania than to the adjacent Maine woods site. The degree and pattern of genetic variation is similar to those of other rare or endemic species of similar habit, i.e. long-lived herbaceous clonal perennials of wide distribution. These results suggest that inbreeding depression has not occurred in Carex polymorpha. Genetic variation is not an apparent factor in its rarity.

Habitat Comments: Primarily an upland species, but it frequently occurs in upland-wetland ecotones and occasionally in sphagnaceous wetlands. Requires strongly acidic, friable soils. Also found in disturbed soil habitats such as those along railroad rights-of-way, sand pits, and small wind dunes.


Carex polymorpha requires strongly acidic and at least seasonally friable soils. Friable consistence seems to be especially important, as this permits the relatively large-diameter, pliable rhizomes to spread. Carex polymorpha is like some other members of the Paniceae which are restricted to loose rooting substrates such as Sphagnum moss, soft muck, etc. (personal observation).

Carex polymorpha is primarily an upland species, but it frequently occurs in wetland ecotones and occasionally Sphagnum. At wetland ecotones supporting this sedge, the soils are seasonally saturated, a condition which apparently contributes to the formation of a thick (6 to 10 inches), dark A-horizon, rich in organic material. In Maine, such an ecotone lies between downslope seeps dominated by Equisetum sylvaticum and Carex crinita, and upslope mixed oak / Gaylussacia baccata forest. In Pennsylvania, the Carex is frequently associated with Lygodium palmatum, a plant similarly dependent on acidic conditions and a seasonal high water table. The Rhode Island occurrence lies on very acidic soils at the ecotone of an upland grazed wooded area with Dennstaedtia punctilobula understory, and a sloping Sphagnum wetland with Scirpus expansus and Carex atlantica. One New Jersey population of Carex polymorpha occurs on an ecotone between a river floodplain and mixed oak woods on the adjacent hillside.

Disturbed soil habitats such as those found along cart roads, railroad rights-of-way, and sand pits are utilized by the species throughout its range. Naturally disturbed soils, small wind dunes atop Panther Knob, West Virginia, are also utilized (Rodney Bartgis, personal communication). Presumably, these habitats are appropriate for seedling establishment, and the open, friable soils permit vegetative spread and relatively long-term maintenance. In all or most cases, Carex polymorpha has colonized disturbed habitats from nearby or adjacent undisturbed habitats. In Maine, Carex polymorpha propagules apparently traveled with gravel taken from the borrow pit site to establish the highway cloverleaf population about one mile away.

Very low natural fertility also characterizes Carex polymorpha soils. Virtually none of the sedge's associated plant species would be described as "nutrient-demanding", and overall community trophic conditions are decidedly oligotrophic. In Pennsylvania, all but one extant population of Carex polymorpha occurs on Clymer series soils, which are highly weathered, leached, and dystrophic (R. Latham, pers. comm.).


Fertile culm production is most prolific on plants growing in full sun, free from dense competing vegetation (personal observation). Quantitative measurements of canopy cover were taken at several locations within the Carex population at one Maine site and the Massachusetts site. A strong correlation between degree of canopy closure and flowering frequency was strongly suggested: canopy closure of less than 50% appears to promote flowering; closure between 50-80% inhibits but does not entirely suppress flowering, and closure greater than 80% appears to suppress flowering completely (Standley and Dudley, 1989). Even when flowering culms are produced at shaded sites, plants do not tend to set seed. Shaded forest sites yield very few fertile culms, though the sterile shoots can be large, dense and apparently vigorous. A forest population in Maine, for example, had thousands of sterile shoots and only about 15 fertile culms in 1987 (personal observation). In mesic red oak orchards of Panther Knob, WV., Carex polymorpha frequently forms a dense understory of vegetative shoots (Bartgis, 1987). It seems likely that increases in light brought about by natural blowdown, fire or logging will stimulate fertile culm formation in this species.

A species similar to Carex polymorpha in terms of light and habitat requirements is Carex foenea. This sedge is rhizomatous and rarely produces fertile culms in shaded forest settings in New England, but fruits when growing in clearings and sandy disturbed sites (personal observation). Another sedge, Carex vestita, is a similarly adapted light-loving, rhizomatous woodland sedge which does best in thick duff or disturbed, sandy openings.


Vegetation supporting Carex polymorpha has burned in Pennsylvania, Massachusetts, West Virginia, Virginia, and probably elsewhere. In most cases the vegetation is dominated by Pinus rigida, Quercus ilicifolia and ericaceous shrubs -- fire prone vegetation. Though the effects of fire on Carex polymorpha have not been precisely determined, persistent growth of the plant in burned areas suggests that it withstands, and possibly is enhanced by fire. Fires might be important in terms of stimulating fertile culm formation since competing woody vegetation is usually diminished. However, in the absence of fire, the plant can persist in mesic forest settings (personal observation).


Carex polymorpha grows within oligotrophic forests, woodland and scrub. On wet-mesic soils, it frequently grows in Pinus strobus - Acer rubrum / Osmunda cinnamomea vegetation; on mesic, high-elevation slopes in Quercus rubra / Dennstaedtia punctilobula vegetation, and in seasonally dry sandy soils of plateaus and plains, in Pinus rigida - Quercus ilicifolia vegetation.


One of the most detailed studies of vegetation associated with Carex polymorpha is that by Gary P. Fleming (1985). In his study, Fleming collected extensive vegetation plot data from the dwarf pine forest atop Panther Knob in West Virginia, which supports the largest known population of this species in the world. He found that Carex polymorpha was locally abundant in the shallow, sandy, level soils of the dwarf pine forest. Most frequent among the herbs in this vegetation were the following species (from Fleming 1985: p. 133): Gaultheria procumbens, Pteridium aquilinum, Carex polymorpha, Maianthemum canadense, Epigaea repens, Aralia nudicaulis, Melampyrum lineare, Lysimachia quadrifolia, Cypripedium acaule, Iris verna, Deschampsia flexuosa, Oryzopsis asperifolia, Aster acuminatus, Dennstaedtia punctilobula, Smilax glauca, Polygala pauciflora, Cornus canadensis, Lycopodium flabelliforme, L. obscurum var. dendroideum, Polypodium virginianum, and Lycopodium annotinum. Woody dominants were Pinus rigida, P. pungens, Gaylussacia baccata, Kalmia latifolia, and Vaccinium angustifolium. Woody associates included Acer rubrum, Quercus rubra var. borealis, Castanea dentata, Acer pensylvanicum, Betula lenta, Pyrus americana, Prunus pensylvanica, Quercus ilicifolia, Amelanchier laevis, Hamamelis virginiana, Ilex montana, Nemopanthus mucronata, Sassafras albidum, Menziesia pilosa, Aronia melanocarpa, Amelanchier sanguinea, and Vaccinium vacillans. Elevation ranges from 4200 to 4500 ft. Panther Knob also supports Carex polymorpha within stunted Quercus rubra woodlands, or "red oak orchards", communities of deeper mesic loamy soil where C. polymorpha forms an often monotypic herbaceous layer. Associates include Acer rubrum, Castanea dentata, Acer pensylvanica, Amelanchier laevis, Hamamelis virginiana, Rhododendron roseum, Kalmia latifolia, Gaylussacia baccata, Aronia melanocarpa, Vaccinium angustifolium, V. vacillans, Deschampsia flexuosa, Maianthemum canadense, Aster acuminatus, Aralis nudicaulis, Dryopteris intermedia, Gaultheria procumbens, Melampyrum lineare, and Pteridium aquilinum.

Two other West Virginia Carex polymorpha populations occur within dwarf pine-heath communities over Tuscarora sandstone ranging from 4000 to 4600 feet in elevation; one population is situated on the border of Virginia (Bartgis, 1987).


Virginia populations of Carex polymorpha are similar to those of West Virginia, occurring primarily on acid soils over sandstone (one population is on granodiorite) at elevations 3200-4200 feet; two populations grow in Quercus rubra forest with Menziesia pilosa, Gaylussacia baccata, and Pteridium aquilinum; another grows in a stunted red oak woodland similar to that of Panther Knob. Four other populations grow in pine or oak-pine vegetation with Calamagrostis porteri, Acer rubrum, Pinus rigida, Gaultheria procumbens, and Kalmia latifolia.


Pennsylvania supports most of the known occurrences of Carex polymorpha, where the plant is associated with extensive plateau pitch pine / scrub oak barrens. Elevations tend to be 1800 to 2000 ft., and the species composition is quite similar to that found at Panther Knob, WV. Common associates documented from the Pennsylvania sites include: Rhododendron canadense, Amianthium muscaetoxicum, Solidago altissima, Kalmia angustifolia, Acer rubrum, and Rubus hispidus; less commonly Gentiana linearis, Lyonia ligustrina, Quercus coccinea, Solidago odora, Spiraea latifolia, Betula populifolia, Comptonia peregrina, Osmunda cinnamomea, Viburnum cassinoides, Lygodium palmatum, Trillium undulatum, Polygonatum pubescens, and Pyrola spp. (Smith 1983, field survey form F83SMI64). Carex vestita is a common associate at the Monroe County site; vegetation plot data from this site are presented in Appendix 1.


The three extant occurrences of Carex polymorpha are situated in northern New Jersey along a five-mile long area following a railroad right-of-way (David Snyder, pers. comm.). One population occurs in an open second growth Quercus rubra and Q. alba woods with sparse Sassafras understory and sparse shrub layer comprised of Rhododendron nudiflorum, Gaylussacia frondosa, Vaccinium stamineum, and Kalmia angustifolia. The herbaceous layer is also sparse and is characterized by Carex spp. and Poa spp., scattered Lysimachia quadrifolia, Pteridium aquilinum, and Solidago rugosa. A second population occurs in two closely associated habitats along the abandoned railroad; one within a mixed oak woods (Quercus rubra, Q. alba), and the other between the berm bordering the right-of-way, and the wooded Acer rubrum swamp. Other associated species at this population include Osmunda cinnamomea, Chimaphila maculata, Monotropa uniflora, Hamamelis virginiana, Pteridium aquilinum, Geranium maculatum, Sassafras albidum, Scirpus hattorianus, Rubus hispidus, Aster divaricatus, Potentilla simplex, Prunus serotina, Solidago bicolor, Vaccinium vacillans, and Cornus florida.


Connecticut's population occurs on a highly disturbed dry forest of Quercus alba, Q. coccinea, Robinia pseudo-acacia, Populus tremuloides, Rhus copallina, Ailanthus altissima; understory is composed of Vaccinium vacillans, Dennstaedtia punctilobula, Smilax glauca, Pteridium aquilinum, Lysimachia quadrifolia, Comptonia peregrina, and Helianthemum canadense.


The one extant population of Carex polymorpha in Massachusetts inhabits thick duff of a wet-mesic Acer rubrum - Pinus strobus forest, and nearby dry sandy soils of low dikes which cross an abandoned commercial cranberry bog. Elevation is 40 feet above sea level. Fertile culms were found only on the sandy dikes where the sedge receives abundant light. Associated plant species on the dikes include Quercus coccinea, Q. alba, Prunus serotina, Rubus hispidus, Schizachyrium scoparium, Agrostis tenuis, Festuca ovina, Smilax rotundifolia, Solidago rugosa, Rosa virginiana, Paspalum setaceum var. muhlenbergii and Gnaphalium obtusifolium (Rawinski and Sorrie, field form F87RAWEO). Cement bridges, about 20 feet wide, apparently have stopped rhizomatous spread of Carex polymorpha northward along the dikes. No Carex plants were found north of the bridges, despite seemingly identical habitat conditions. This observation suggests that reproduction via seed may be rare at this site, and further suggests the importance of vegetative reproduction in this species.


New Hampshire supports a population second in size to that in West Virginia; it occurs on deep sandy soils in an area characterized by abundant Pinus rigida, P. strobus, Populus tremuloides, Quercus rubra, Osmunda cinnamomea. C. polymorpha is found in several disturbed areas (railroad edge and along a roadside) as well as in a Quercus-Pinus woods on seasonally wet sandy soils adjacent to wetlands.


Five extant occurrences known in Maine are found in a two square-mile area near the coast. Three are in wooded areas: two in forests of Quercus rubra, Fagus grandifolia, Acer rubrum, Hamamelis virginiana, Viburnum acerifolium, and Castanea dentata, and another in Pinus strobus forest with a sparse herb layer. Two populations are in disturbed areas, one a highway cloverleaf, and the other in a borrow pit and adjacent woods. Vegetation plot data from two Maine Carex polymorpha sites are presented in Appendix 2.


A single population in Rhode Island occurs at the ecotone of a seepage swamp harboring Carex folliculata, C. atlantica, Symplocarpus foetidus, and an upland forest of Acer rubrum, Nyssa sylvatica, Quercus rubra, Fagus grandifolia, Pinus strobus in the canopy and Kalmia angustifolia, Mitchella repens, Medeola virginiana, and Carex swanii in the herb layer. This population is small and produces very few flowering culms.

Economic Attributes Not yet assessed
Management Summary
Stewardship Overview: Standley and Dudley (1989) recommend the monitoring of both areal extent and shoot density of populations. Monitoring of population size and shoot density should be done every three to five years.
Restoration Potential: The clonal growth habit, with long rhizomes capable of partitioning resources in marginally suitable habitat and short rhizomes that aggressively colonize more open habitat would suggest that the recovery potential of damaged populations is excellent, given that other suitable microsites are available or can be created.
Monitoring Requirements: Standley and Dudley (1989) recommend the monitoring of both areal extent and shoot density of populations. Population borders should be marked permanently at several points, in relation to permanent landmarks. Shoot density may be measured by 3 permanent square-meter plots in each population or subpopulation, or alternatively by 10-cm wide strips along 10-meter long line transects measured at given intervals. 10 to 20 replications are recommended. Numbers of flowering and vegetative shoots should be counted at each point. Monitoring of population size and shoot density should be done every three to five years.
Monitoring Programs: The Maine Field Office of The Nature Conservancy initiated annual monitoring of two populations in 1991.
Management Research Programs: Range-wide status surveys were conducted in the summer of 1987 for the USFWS, coordinated by The Nature Conservancy's Eastern Heritage Task Force.

A study of population size and structure of Carex polymorpha, and associated vegetation, was conducted at Panther Knob, WV for the West Virginia Field Office of The Nature Conservancy.

Management Research Needs: Research needs are outlined by Standley and Dudley (1989) as follows:

1) Seed germination and establishment: further information may reveal causes for rarity, and be necessary in the long-term management of populations.

2) Disturbance: canopy thinning, litter removal, prescribed burning.

3) Greenhouse experiments: effects of various light levels in stimulation of sexual reproduction should be tested. Effects of soil nutrients, texture, and moisture on growth and reproduction would also provide additional information on resource requirements.

4) Searches for new populations: Prior to intensive inventory efforts, field botanists should visit as many known populations as possible to gain insight into habitat requirements and associated species. In glaciated regions, searching sandy areas adjacent to wetlands and appropriate soil types may yield additional populations. In Pennsylvania, extant populations show high fidelity to Clymer series soils that overly remnants of Illinoisan till (R. Latham, pers. comm.) Standley and Dudley (1989) recommend that education of field staff regarding the taxonomic characters, particularly vegetative ones, may produce the most efficient results.

Much might be learned through comparative studies of Carex polymorpha and the related species, Carex panicea. Although it is not native to North America, Carex panicea is locally established here, and occupies habitats similar to those utilized by Carex polymorpha. At a Massachusetts site, Carex panicea grows along the upper border of an acidic, seepy pasture with Kalmia angustifolia, Vaccinium macrocarpon, Aster novi-belgii, Schizachyrium scoparium, and Lycopodium inundatum.

Future ecological studies should focus on the hydrology of Carex polymorpha soils. Because many of the soils are seasonally saturated and sloping, lateral drainage takes place. This suggests that upslope lands should also be protected to preserve the natural hydrological regime and the sedge.

Population/Occurrence Delineation Not yet assessed
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 14Nov1997
NatureServe Conservation Status Factors Author: Harmon, P.J., rev. K. Maybury/S. Norris (1996)
Management Information Edition Date: 30Jan1992
Management Information Edition Author: THOMAS J. RAWINSKI; LESLEY A. SNEDDON

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

  • Bartgis, R.L. 1987. Status surveys in WV for CAREX POLYMORPHA, SPIRAEA VIRGINIANA, and THALICTRUM STEELEANUM. November 1987. WV Dept. of Natural Resources, Wildlife Resources Division, Elkins, WV 26241.

  • Everett, M. 2001. Carex polymorpha (Variable sedge) Conservation and Research Plan. New England Wild Flower Society, Framingham, Massachusetts, USA (

  • Fernald, M.L. 1950. Gray's Manual of Botany, 8th ed., Corr. Printing, 1970. Van Nostrand, New York. LXIV+1632 pp.

  • Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.

  • Fleming, G.P. 1985. A study of the dwarf pine forest and Carex polymorpha Muhl. on Panther Knob, West Virginia. Final report to The Nature Conservancy, West Virginia Field Office. 149 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.

  • Hough, M. Y. 1983. New Jersey Wild Plants. Harmony Press, Harmony, New Jersey. 414 pp.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.



  • Rawinski, T.J. 1988. Final status survey report: The distribution and abundance of variable sedge (Carex polymorpha). Submitted to the U.S. Fish and Wildlife Service, Region 5, Newton Corner, MA. 14 pp.

  • Rawinski, T.J. 1989. Status survey report, Variable sedge (Carex polymorpha) in Maine. Unpublished report to the Maine Natural Heritage Program. The Nature Conservancy, Eastern Heritage Task Force. Boston, MA.

  • Rawinski, T.J. 1990. Final status survey report: The distribution and abundance of variable sedge (Carex polymorpha). Unpublished report submitted to U.S. Fish and Wildlife Service, Region 5. Newton Corner, Massachusetts, USA.

  • Rawinski, T.J. 1990. Range-wide status summary of variable sedge (Carex polymorpha) as of February, 1990. The Nature Conservancy, Eastern Heritage Task Force. Boston, MA.

  • Rothrock, P.E. and A.A. Reznicek. 2002. Carex Linnaeus sect. Paniceae G. Don. Pages 426-431 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, NY, USA. 608pp + xxiv.


  • Smith, T.L. 1990. 1989 U.S. Fish and Wildlife Service candidate plant species survey for eastern Pennsylvania. Unpublished report.

  • Standley, L.A. and J.L. Dudley. 1990. Population biology of the globally rare sedge Carex polymorpha. Prepared for Massachusetts Natural Heritage and Endangered Species Program; The Nature Conservancy, Maine Chapter; and Pennsylvania Department of Environmental Resources.

  • Standley, L.A., J.L. Dudley, and L.P. Bruederle. 1991. Electrophoretic variability in the rare sedge, Carex polymorpha (Cyperaceae). Bull. Torrey Botanical Club 118: 444-450.

  • Standley, L.A., and J.L. Dudley. 1989. Population biology of the globally rare sedge Carex polymorpha. Unpublished report to the Massachusetts Natural Heritage Program, Westborough.

  • Standley, L.A., and J.L. Dudley. 1991. Vegetative and sexual reproduction in the rare sedge Carex polymorpha (Cyperaceae). Rhodora 93: 268-290.

  • Virginia Natural Heritage Program. 1988. Status survey for Carex polymorpha (Variable sedge) in Virginia. Unpublished report.

  • 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

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