Rhynchospora knieskernii
Encyclopedia
Rhynchospora knieskernii is a rare species of sedge
known by the common name Knieskern's beaksedge. It is endemic to the state of New Jersey
in the United States, where it occurs only in the Pine Barrens
. 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
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
s. The seeds require cold and wet stratification
, as well as light, in order to germinate.
The plant is limited to the Pine Barrens of southern New Jersey. It has been collected within the state of Delaware
, but it has not been seen there in over a century and it is considered extirpated
. It is a plant of wetland
s. It grows in wet, disturbed habitat, such as recently burned areas. Its habitat has fluctuating groundwater
levels; it is tolerant of drought
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
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
deposits, where a slow current causes gradual erosion
and the soil chemistry
is not hospitable to many other species. The habitat is often dominated
by pitch pine
(Pinus rigida) in the Pine Barrens. Other plants in the area include poverty grass (Aristida longispica), warty panic-grass (Panicum verrucosum), and spatulate-leaved sundew
(Drosera intermedia).
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
featuring periodic 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. This has reduced the sedge's population and it now grows in areas that are artificially disturbed. These habitat types may include gravel
, clay
, and sand mines
, 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 artifically cleared habitat it faces threats from human activity, such as mining, off-road vehicle
use, road maintenance, and development. 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.
Cyperaceae
Cyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble grasses or rushes. The family is large, with some 5,500 species described in about 109 genera. These species are widely distributed, with the centers of diversity for the group...
known by the common name Knieskern's beaksedge. It is endemic to the state of New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
in the United States, where it occurs only in the Pine Barrens
Pine Barrens (New Jersey)
The Pine Barrens, also known as the Pinelands, is a heavily forested area of coastal plain stretching across southern New Jersey. The name "pine barrens" refers to the area's sandy, acidic, nutrient-poor soil, to which the crops originally imported by European settlers didn't take well...
. 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
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. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
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
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 often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
s. The seeds require cold and wet stratification
Stratification
Stratification is the building up of layers. Stratified is an adjective referring to the arranging of layers, and is also the past form of the verb stratify, to separate or become separated into layers...
, as well as light, in order to germinate.
The plant is limited to the Pine Barrens of southern New Jersey. It has been collected within the state of Delaware
Delaware
Delaware is a U.S. state located on the Atlantic Coast in the Mid-Atlantic region of the United States. It is bordered to the south and west by Maryland, and to the north by Pennsylvania...
, but it has not been seen there in over a century and it is considered extirpated
Local extinction
Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...
. It is a plant of wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
s. It grows in wet, disturbed habitat, such as recently burned areas. Its habitat has fluctuating groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
levels; it is tolerant of drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
but also prefers very wet substrates. It appears in early successional
Ecological succession
Ecological succession, is the phenomenon or process by which a community progressively transforms itself until a stable community is formed. It is a fundamental concept in ecology, and refers to more or less predictable and orderly changes in the composition or structure of an ecological community...
stages of disturbed habitat, taking hold before most other plants move in; it does not compete
Competition (biology)
Competition is an interaction between organisms or species, in which the fitness of one is lowered by the presence of another. Limited supply of at least one resource used by both is required. Competition both within and between species is an important topic in ecology, especially community ecology...
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
Bog iron refers to impure iron deposits that develop in bogs or swamps by the chemical or biochemical oxidation of iron carried in the solutions. In general, bog ores consist primarily of iron oxyhydroxides, commonly goethite...
deposits, where a slow current causes gradual erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
and the soil chemistry
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.-History:...
is not hospitable to many other species. The habitat is often dominated
Dominance (ecology)
Ecological dominance is the degree to which a species is more numerous than its competitors in an ecological community, or makes up more of the biomass...
by pitch pine
Pitch Pine
The Pitch Pine, Pinus rigida, is a small-to-medium sized pine, native to eastern North America. This species occasionally hybridizes with other pine species such as Loblolly Pine , Shortleaf Pine , and Pond Pine The Pitch Pine, Pinus rigida, is a small-to-medium sized (6-30 meters or 20-100 feet)...
(Pinus rigida) in the Pine Barrens. Other plants in the area include poverty grass (Aristida longispica), warty panic-grass (Panicum verrucosum), and spatulate-leaved sundew
Drosera intermedia
Drosera intermedia, commonly known as the oblong-leaved sundew or spoonleaf sundew, is an insectivorous plant species belonging to the sundew genus. It is a temperate or tropical species native to Europe, southeastern Canada, the eastern half of the United States, Cuba and northern South America.-...
(Drosera intermedia).
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
Fire regime
A fire regime is the pattern, frequency and intensity of the bushfires and wildfires that prevails in an area. It is an integral part of fire ecology, and renewal for certain types of ecosystems. If fires are too frequent, plants may be killed before they have matured, or before they have set...
featuring periodic wildfire
Wildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
. 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. This has reduced the sedge's population and it now grows in areas that are artificially disturbed. These habitat types may include gravel
Gravel
Gravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel can be sub-categorized into granule and cobble...
, clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
, and sand mines
Sand mining
Sand mining is a practice that is becoming an environmental issue as the demand for sand increases in industry and construction. Sand is mined from beaches and inland dunes and dredged from ocean beds and river beds. It is often used in manufacturing as an abrasive, for example, and it is used to...
, 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 artifically cleared habitat it faces threats from human activity, such as mining, off-road vehicle
Off-road vehicle
An off-road 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 deep, open treads, a flexible suspension, or even caterpillar tracks...
use, road maintenance, and development. 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.