''Phragmites australis'', known as the common reed, is a species of plant. It is a broadly distributed wetland grass that can grow up to tall.

Description

''Phragmites australis'' commonly forms extensive stands (known as

reed bed A reedbed or reed bed is a natural habitat found in floodplains, waterlogged depressions and estuaries. Reedbeds are part of a succession from young reeds colonising open water or wet ground through a gradation of increasingly dry ground. As ...

s), which may be as much as or more in extent. Where conditions are suitable it can also spread at or more per year by horizontal runners, which put down

root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...

s at regular intervals. It can grow in damp ground, in standing water up to or so deep, or even as a floating mat. The erect stems grow to tall, with the tallest plants growing in areas with hot summers and fertile growing conditions. The leaves are long and broad. The

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 are produced in late summer in a dense, dark purple

panicle A panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit In botany, a fruit is the seed-bearing structure in flowering plants that is ...

, about long. Later the numerous long, narrow, sharp pointed spikelets appear greyer due to the growth of long, silky hairs. These eventually help disperse the minute seeds.

Taxonomy

Recent studies have characterized morphological distinctions between the introduced and native stands of ''Phragmites australis'' in North America. The Eurasian phenotype can be distinguished from the North American phenotype by its shorter

ligule A ligule (from "strap", variant of ''lingula'', from ''lingua'' "tongue") is a thin outgrowth at the junction of leaf and leafstalk of many Poaceae, grasses (Poaceae) and Cyperaceae, sedges. A ligule is also a strap-shaped extension of the corolla ...

s of up to as opposed to over 1 mm, shorter glumes of under against over 3.2 mm (although there is some overlap in this character), and in culm characteristics. * ''Phragmites australis'' subsp. ''americanus'' – the North American genotype has been described as a distinct species, ''

Phragmites americanus ''Phragmites americanus'', common name American reed, is a species of plant found in North America. It is listed as a special concern in Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern Un ...

'' * ''Phragmites australis'' subsp. ''australis'' – the Eurasian genotype * ''Phragmites australis'' subsp. ''altissimus'' (Benth.) Clayton * ''Phragmites australis'' var. ''marsillyanus'' (Mabille) Kerguélen

Ecology

It is a helophyte (

aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments ( saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

), especially common in

alkali In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of ...

ne habitats, and it also tolerates

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

water, and so is often found at the upper edges of

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environme ...

and on other wetlands (such as grazing marsh) which are occasionally inundated by the sea. A study demonstrated that ''P. australis'' has similar greenhouse gas emissions to native ''

Spartina alterniflora ''Sporobolus alterniflorus'', or synonymously known as ''Spartina alterniflora'', the smooth cordgrass, saltmarsh cordgrass, or salt-water cordgrass, is a perennial deciduous grass which is found in intertidal wetlands, especially estuarine salt ...

''. However, other studies have demonstrated that it is associated with larger

methane emissions Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane ...

and greater carbon dioxide uptake than native New England salt marsh vegetation that occurs at higher marsh elevations. Common reed is suppressed where it is

grazed In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other f ...

regularly by

livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to anima ...

. Under these conditions it either grows as small shoots within the grassland sward, or it disappears altogether. In

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...

, common reed is rarely invasive, except in damp

grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...

s where traditional

grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...

has been abandoned.

Invasive status

In North America, the status of ''Phragmites australis'' is a source of confusion and debate. It is commonly considered a non-native and often

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...

, introduced from Europe in the 1800s. However, there is evidence of the existence of ''Phragmites'' as a

native plant In biogeography, a native species is indigenous to a given region or ecosystem if its presence in that region is the result of only local natural evolution (though often popularised as "with no human intervention") during history. The term is equ ...

in North America long before European colonization of the continent. The North American native subspecies, ''P. a.'' subsp. ''americanus'' (sometimes considered a separate species, ''P. americanus''), is markedly less vigorous than European forms. The expansion of ''Phragmites'' in North America is due to the more vigorous, but similar-looking European subsp. ''australis''. ''Phragmites australis'' subsp. ''australis'' outcompetes native vegetation and lowers the local plant

biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity' ...

. It forms dense thickets of vegetation that are unsuitable

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

for native

fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is ''flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as ''biota''. Zoo ...

. It displaces native plants species such as

wild rice Wild rice, also called manoomin, Canada rice, Indian rice, or water oats, is any of four species of grasses that form the genus ''Zizania'', and the grain that can be harvested from them. The grain was historically gathered and eaten in both ...

, cattails, and native

orchids Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest families of flowering ...

. ''Phragmites'' has a high above ground biomass that blocks light to other plants allowing areas to turn into ''Phragmites''

monoculture In agriculture, monoculture is the practice of growing one crop species in a field at a time. Monoculture is widely used in intensive farming and in organic farming: both a 1,000-hectare/acre cornfield and a 10-ha/acre field of organic kale a ...

very quickly. Decomposing ''Phragmites'' increases the rate of marsh accretion more rapidly than would occur with native marsh vegetation. ''Phragmites australis'' subsp. ''australis'' is causing serious problems for many other North American hydrophyte wetland plants, including the native ''P. australis'' subsp. ''americanus''. Gallic acid released by phragmites is degraded by

ultraviolet light Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiati ...

to produce

mesoxalic acid Mesoxalic acid, also called oxomalonic acid or ketomalonic acid, is an organic compound with formula C3H2O5 or HO−(C=O)3−OH. Mesoxalic acid is both a dicarboxylic acid and a ketonic acid. It readily loses two protons to yield the divalent ...

, effectively hitting susceptible plants and seedlings with two harmful toxins. ''Phragmites'' is so difficult to control that one of the most effective methods of eradicating the plant is to burn it over 2–3 seasons. The roots grow so deep and strong that one burn is not enough. Ongoing research suggests that goats could be effectively used to control the species.

Natural enemies

Since 2017, over 80% of the beds of ''Phragmites'' in the Pass a Loutre Wildlife Management Area have been damaged by the invasive roseau cane scale (''

Nipponaclerda biwakoensis ''Nipponaclerda biwakoensis'' is a scale insect originally described from Japan, and naturally occurring in China; in these countries it is most often associated with reeds in the genus ''Phragmites''. This species has become established (as of 2 ...

''), threatening wildlife habitat throughout the affected regions of the area. While typically considered a noxious weed, in

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a U.S. state, state in the Deep South and South Central United States, South Central regions of the United States. It is the List of U.S. states and territories by area, 20th-smal ...

the reed beds are considered critical to the stability of the shorelines 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 ...

areas and waterways of the

Mississippi Delta The Mississippi Delta, also known as the Yazoo–Mississippi Delta, or simply the Delta, is the distinctive northwest section of the U.S. state of Mississippi (and portions of Arkansas and Louisiana) that lies between the Mississippi and Yaz ...

, and the die-off of reed beds is believed to accelerate

coastal erosion Coastal erosion is the loss or displacement of land, or the long-term removal of sediment and rocks along the coastline due to the action of waves, currents, tides, wind-driven water, waterborne ice, or other impacts of storms. The landwa ...

Uses

The entire plant is edible raw or cooked. The young stems can be boiled, or later on be used to make flour. The underground stems can be used but are tough, as can the seeds but they are hard to find. Stems can be made into eco-friendly drinking straws. Many parts of the plant can be eaten. The young shoots can be consumed raw or cooked. The hardened sap from damaged stems can be eaten fresh or toasted. The stems can be dried, ground, sifted, hydrated, and toasted like marshmallows. The seeds can be crushed, mixed with berries and water, and cooked to make a gruel. The roots can be prepared similar to those of cattails. Common Reeds are also the primary source of thatch for traditional thatch housing in Europe and beyond. The plant is extensively used in phytodepuration, or natural water treatment systems, since the root hairs are excellent at filtering out impurities in waste water. Phragmites australis also shows excellent potential as a source of biomass.