''Juncus acutiflorus'', also called sharp-flowered rush, is a rush or a grassy plant of the genus ''

Juncus ''Juncus'' is a genus of monocotyledonous flowering plants, commonly known as rushes. It is the largest genus in the family Juncaceae, containing around 300 species. Description Rushes of the genus ''Juncus'' are herbaceous plants that superfic ...

''. As the name suggests, the plant has notable sharp-looking

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...

s, flowering between July and September.

Description

The plant has leaves shaped round or elliptical in cross-section, with darker horizontal lines visible against the light at intervals, like in the jointed rush. During

pollination Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds ...

, new

branch A branch, sometimes called a ramus in botany, is a woody structural member connected to the central trunk of a tree (or sometimes a shrub). Large branches are known as boughs and small branches are known as twigs. The term '' twig'' usually ...

es emerge from the old ones and multiply to resemble a small bush. The flowers have various shades of warm brown and maroon. Fruits look like a small pointed capsule. It grows straight and measures about 3 feet tall. The leaves are straight, smooth and circular in section, hollow, with transverse septa making the leaf feel jointed while touching and holding.

Ecology and habitat

The plant commonly grows on acid soils in swampy

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 and wet

heathland A heath () is a shrubland habitat (ecology), habitat found mainly on free-draining infertile, acidic soils and characterised by open, low-growing woody vegetation. Moorland is generally related to high-ground heaths with—especially in Great B ...

and

woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (see ...

s. The species is widespread in the areas of and nearby northern

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

. This plant is sensitive to

nitrate Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble ...

levels in the environment. In a Dutch rich-fen,

chlorosis In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to ...

has been noted in stands of ''Juncus acutiflorus'' at locations where groundwater containing high levels of nitrate reached the surface. Experiments revealed that the chlorosis could be attributed to

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...

deficiency although iron levels in the shoots were well above the known physiological threshold values for iron deficiency. Nowadays, nitrate concentrations in ground water as high 1000 μM are no longer an exception in the

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

Similar species

The species resembles ''

Juncus articulatus ''Juncus articulatus'' is a flowering plant species in the rush family Juncaceae. It is known by the common name jointleaf rush or jointed rush, which can also refer to '' J. kraussii'' from Australia. It is native to Eurasia, Canada, Greenland ...

'' (the jointed rush) known by the common names 'jointed rush' and 'jointleaf rush'. It is native to

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...

and much of

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...

and the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

. It grows in moist areas, such as wet sand, and thrives in

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an a ...

soils. This is a

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

herb producing a mainly erect stem from a short rhizome. The stem may root at nodes, and it generally has one or more cylindrical leaves up to 10 centimeters long. It resembles this species as the leaves appear same, but the tepals are completely different. They are almost blackish-brown, and the main branches are often almost horizontal in the jointed rush.

Hybrids

Two hybrids or subspecies of sharp-flowered rush are known – ''Juncus acutiflorus'' subsp. ''acutiflorus'' (also called ''Juncus acutiflorus'' t.infr. ''effusus'' and ''Juncus acutiflorus'' var. ''exoletus'') and ''Juncus acutiflorus'' ssp. ''rugosus''. They are formed by the hybridization of sharp-flowered rush and the smaller-sized jointed rush.

References

External links

* * {{Taxonbar, from=Q161333 acutiflorus Plants described in 1791