''Rhynchospora knieskernii'' is a rare species of

sedge The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' wit ...

known by the common name Knieskern's beaksedge. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the state of

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

in the United States, where it occurs naturallyin the

Pine Barrens Pine barrens, pine plains, sand plains, or pineland areas occur throughout the U.S. from Florida to Maine (see Atlantic coastal pine barrens) as well as the Midwest, West, and Canada and parts of Eurasia. Perhaps the most well known pine-barre ...

. Reports have cited it present in

Delaware Delaware ( ) is a state in the Mid-Atlantic region of the United States, bordering Maryland to its south and west; Pennsylvania to its north; and New Jersey and the Atlantic Ocean to its east. The state takes its name from the adjacent Del ...

as well, but these populations appear to have been introduced.Biota of North America Program 2014 county distribution map
/ref> It is threatened by the destruction and degradation of its habitat. It is a federally listed threatened species of the United States. This perennial sedge produces clumps of very narrow, triangular stems lined with thin leaves.

Inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

s occur at the tips and on the sides of the stems. Each contains two to four tight clusters of dark brown spikelets and leaflike

bract In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...

s.''Rhynchospora knieskernii''.
Flora of North America. The seeds require cold and wet

stratification Stratification may refer to: Mathematics * Stratification (mathematics), any consistent assignment of numbers to predicate symbols * Data stratification in statistics Earth sciences * Stable and unstable stratification * Stratification, or str ...

, as well as light, in order to

germinate Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...

.USFWS
''Rhynchospora knieskernii'' Five-year Review.
August 2008. The plant is limited to the Pine Barrens of southern New Jersey. It has been collected within the state of

, but it has not been seen there in over a century and it is considered

extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

. It is a plant of

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

s. It grows in wet, disturbed habitat, such as recently burned areas. Its habitat has fluctuating

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...

levels; it is tolerant of

drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

but also prefers very wet substrates. It appears in early successional stages of disturbed habitat, taking hold before most other plants move in; it does not

compete Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...

well with other plants. It grows in habitat that has relatively few other plants due to disturbance, chemistry, a variable water supply, and other factors. Substrates are low in nutrients and high in minerals. It is known from streams rich in

bog iron Bog iron is a form of impure iron deposit that develops in bogs or swamps by the chemical or biochemical oxidation of iron carried in solution. In general, bog ores consist primarily of iron oxyhydroxides, commonly goethite (FeO(OH)). Iron-bea ...

deposits, where a slow current causes gradual

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

and the

soil chemistry Soil chemistry is the study of the chemical characteristics of soil. Soil chemistry is affected by mineral composition, organic matter and environmental factors. In the early 1850s a consulting chemist to the Royal Agricultural Society in England, ...

is not hospitable to many other species. The habitat is often dominated by

pitch pine ''Pinus rigida'', the pitch pine, is a small-to-medium-sized pine. It is native to eastern North America, primarily from central Maine south to Georgia and as far west as Kentucky. It is found in environments which other species would find unsuit ...

(''Pinus rigida'') in the Pine Barrens. Other plants in the area include

poverty grass Poverty grass is a common name for several plants and may refer to: *Any of several grasses that grow in poor or sandy soil, for example: ** '' Aristida dichotoma'', Shinner's three-awn ** ''Eremochloa bimaculata'' ** ''Sporobolus vaginiflorus'', ...

(''Aristida longispica''), warty panic-grass (''Panicum verrucosum''), and spatulate-leaved sundew (''Drosera intermedia'').''Rhynchospora knieskernii''.
Center for Plant Conservation. This sedge is intolerant of shade and it does not grow in areas where large and woody vegetation would shade it out. It naturally grows in pine forest that is maintained by a natural

fire regime A fire regime is the pattern, frequency, and intensity of the bushfires and wildfires that prevail in an area over long periods of time. It is an integral part of fire ecology, and renewal for certain types of ecosystems. A fire regime describes th ...

featuring periodic

wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire ...

. Fires prevent the buildup of vegetation and allow sun to reach smaller plants, such as the sedge. The seeds probably cannot germinate if there is a large buildup of organic matter on the soil surface, such as leaf litter. Today there are few areas where such a natural fire regime can still occur because of the widespread practice of

fire suppression Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts in wild land areas require different techniques, equipment, and training from the more familiar structure fire fighting found in populated a ...

. This has reduced the sedge's population and it now grows in areas that are artificially disturbed. These habitat types may include

gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

, and

sand mines Sand mining is the extraction of sand, mainly through an open pit (or sand pit) but sometimes mining, mined from beaches and inland dunes or dredging, dredged from ocean and stream bed, river beds. Sand is often used in manufacturing, for example ...

, pits, and ditches, railroads, clearings, and unpaved roads. Threats to this species mostly involve the loss of its wet, disturbed habitat. In areas where fire is suppressed, the overgrowth of vegetation shades out the sedge and populations disappear. In artificially cleared habitat it faces threats from human activity, such as mining,

off-road vehicle An off-road vehicle, sometimes referred to as an overland or adventure vehicle, is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with dee ...

use, road maintenance, and development.''Rhynchospora knieskernii''.
The Nature Conservancy. Trash dumping occurs at some sites. In 2007 there were 45 occurrences of the plant, but few of these have been surveyed recently enough to confirm the presence of the plant.

References

External links

USDA Plants Profile
{{Taxonbar, from=Q7321725 knieskernii Flora of New Jersey Flora of Delaware Plants described in 1847