''Leersia hexandra'' is a species of
grass
Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in law ...
known by the common names southern cutgrass, clubhead cutgrass, and swamp rice grass.
[''Leersia hexandra''.]
Pacific Island Ecosystems at Risk (PIER). It has a
pantropical
A pantropical ("all tropics") distribution is one which covers tropical regions of both hemispheres. Examples of species include caecilians, modern sirenians and the plant genera ''Acacia'' and '' Bacopa''.
'' Neotropical'' is a zoogeographic t ...
distribution.
It is also an
introduced species
An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived the ...
in many regions, sometimes becoming
invasive
Invasive may refer to:
*Invasive (medical) procedure
*Invasive species
*Invasive observation, especially in reference to surveillance
*Invasively progressive spread of disease from one organ in the body to another, especially in reference to cancer ...
, and it is an
agricultural weed of various crops,
[ especially ]rice
Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly '' Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and ''Porteresia'', both wild and domestica ...
.[CABI. (2013)]
''Leersia hexandra''.
In: Invasive Species Compendium. Wallingford, UK: CAB International. It is also cultivated as a forage
Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also us ...
for 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 ...
.[''Leersia hexandra''.]
FAO.
Description
This species is a perennial grass growing from rhizomes and stolon
In biology, stolons (from Latin '' stolō'', genitive ''stolōnis'' – "branch"), also known as runners, are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external ...
s. The hollow stems are decumbent and creeping and root easily where their nodes contact the substrate. They produce erect shoots that can exceed one meter tall.[''Leersia hexandra''.]
Flora of China. It is an aquatic or semi-aquatic grass, and the erect stem parts may float in water.[Pyrah, G. L]
''Leersia hexandra''.
Grass Manual. Flora of North America. These stems can grow densely in aquatic habitat and become matted, forming what are often referred to as "carpets".[''Leersia hexandra''.]
In: ''Flora of West Tropical Africa'' vol. 3, part 2. 1972. JSTOR Global Plants.
The leaf sheath has a fleshy base covered in white hairs and the 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 ...
can be stiff and dry,[ becoming "papery".][''Leersia hexandra''.]
Center for Aquatic and Invasive Plants. University of Florida IFAS. The leaves have sharp-pointed blades up to 30 centimeters long which are flat or rolled, the edges sometimes rolling at night or when the blade dries.[ The blades are sometimes hairless,][ but are usually coated in very rough hairs, making them so rough to the touch that they are "unpleasant to handle".][ They also have very sharp edges,][ and the midrib has backward-facing, spiny hairs that give it a cutting edge. The "retrorsely spinulose midrib of the leaf can inflict most painful lacerations".][
The ]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 ...
is narrow or spreading and erect or nodding, and up to about 12 centimeters long. The branches are almost fully lined with overlapping spikelets each up to half a centimeter long.[ The spikelets may be greenish or purplish in color,][ or sometimes tinged with orange or brick red.][ They are surrounded by white or purplish bracts that have characteristic comb-like hairs along their greenish nerves.][ The flower has six ]stamen
The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filam ...
s.[ After the spikelets fall, the panicle branches have a zig-zag shape.][ Fertile seed is rarely produced and the grass commonly reproduces vegetatively by sprouting from the rhizome or the nodes on the stem.][ Large stands of the grass are often clones.][
This grass looks very similar to rice and other species of the genus '']Oryza
''Oryza'' is a genus of plants in the grass family. It includes the major food crop rice (species ''Oryza sativa'' and ''Oryza glaberrima''). Members of the genus grow as tall, wetland grasses, growing to tall; the genus includes both annual a ...
''. It is a member of the rice tribe Oryzeae and sometimes grows in rice paddies
A paddy field is a flooded field of arable land used for growing semiaquatic crops, most notably rice and taro. It originates from the Neolithic rice-farming cultures of the Yangtze River basin in southern China, associated with pre-A ...
.[
]
Ecology
This plant grows in shallow freshwater
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does in ...
habitat and on wet and moist land. It can be found in marsh
A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found a ...
es, swamps, ponds, irrigation
Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been dev ...
ditches, flooded rice fields, and on other moist agricultural land and floodplain
A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
s. It is mostly tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
, but it can grow in some temperate climate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout ...
s.[ It can persist for a time in drier conditions during ]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 ...
.[
The grass provides food and shelter for animals. Many ]water bird
A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term ''water bird'' is especially applied to birds in freshwater ecosystems, although others make no distinction from sea ...
s feed on it.[ In ]Tanzania
Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands ...
it is a dominant plant in the swamps where the shoebill (''Balaeniceps rex'') and wattled crane (''Bugeranus carunculatus'') build their nests. On the Llanos
The Llanos ( Spanish ''Los Llanos'', "The Plains"; ) is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the tropical and subtropical grasslands, ...
of Colombia and Venezuela
Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in ...
it is the second most important food of the resident herds of capybara
The capybaraAlso called capivara (in Brazil), capiguara (in Bolivia), chigüire, chigüiro, or fercho (in Colombia and Venezuela), carpincho (in Argentina, Paraguay and Uruguay) and ronsoco (in Peru). or greater capybara (''Hydrochoerus hydro ...
(''Hydrochoerus hydrochaeris''), composing up to 29% of their diet.[
It is one of the two host plants of the ]brown planthopper
The brown planthopper (BPH), ''Nilaparvata lugens'' (Stål) (Hemiptera: Delphacidae) is a planthopper species that feeds on rice plants (''Oryza sativa'' L.). These insects are among the most important pests of rice, which is the major staple cr ...
(''Nilaparvata lugens''), the other being cultivated rice. While it has been observed on many other plant species, it can only complete its life cycle on cutgrass or rice. There are two strains of the planthopper, one that only lays eggs on rice and one that favors cutgrass; the rice strain does not effectively reproduce on cutgrass and vice versa, even when sympatric
In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species s ...
. While they can be crossed in laboratory tests, the two strains do not interbreed in the wild.
As a weed
The grass is a weed of several crops, including tea, rubber
Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, a ...
, maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn ( North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. ...
, and sugarcane, but especially rice. It is a relative of the rice plant and it thrives in paddy fields. Its vegetation "carpets" clog irrigation waterways, causing flooding and erosion. It hosts many rice pests
PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...
, including the brown planthopper, the green planthopper
''Siphanta acuta'' is a species of planthopper in the family Flatidae; this species is native to Australia, but is now found in various other parts of the world. About 10 mm long, they resemble small leaves and are generally found in trees.
...
(''Nilaparvata bakeri''), the green rice leafhopper
Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combina ...
(''Nephotettix malayanus''), the rice gall midge (''Orseolia oryzae''), and the moth ''Helcystogramma arotraeum
''Helcystogramma arotraeum'' is a moth in the family Gelechiidae. It was described by Edward Meyrick in 1894. It is known from Japan, Taiwan, China (Hainan, Jiangxi, Yunnan), Myanmar, Thailand, northeastern India, Sri Lanka, Malaysia, and Indone ...
''.[ It hosts the rice stem nematode, which causes ufra disease of rice.][ It is susceptible to many plant viruses that infect rice plants, such as rice grassy stunt virus, rice transitory yellowing virus, and rice tungro virus. It is susceptible to bacteria and ]fungi
A fungus (plural, : fungi or funguses) is any member of the group of Eukaryote, eukaryotic organisms that includes microorganisms such as yeasts and Mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified ...
such as pathogenic '' Xanthomonas oryzae'', which causes leaf blight
Blight refers to a specific symptom affecting plants in response to infection by a pathogenic organism.
Description
Blight is a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral or ...
of rice, and ''Cochliobolus miyabeanus
''Cochliobolus miyabeanus'' (formerly known as ''Helminthosporium oryzae'') is a fungus that causes brown spot disease in rice.
It was considered for use by the USA as a biological weapon against Japan during World War II.
Hosts and symptoms
B ...
'', which causes brown spot.[
]
Uses
Despite its sharp leaf edges, the grass is palatable to cattle
Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Adult females are referred to as cows and adult ...
and it is maintained as a pasture
Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep, or s ...
grass on swampy land and cut for hay.[
This species is a ]hyperaccumulator A hyperaccumulator is a plant capable of growing in soil or water with very high concentrations of metals, absorbing these metals through their roots, and concentrating extremely high levels of metals in their tissues. The metals are concentrated a ...
of heavy metals
upright=1.2, Crystals of lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead
Heavy metals are generally defined as metals with relatively high density, densities, atomi ...
, with the ability to take up large amounts of chromium
Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal.
Chromium metal is valued for its high corrosion resistance and h ...
, copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish ...
, and nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...
from water and soil.[You, S., et al. (2013)]
Feasibility of constructed wetland planted with ''Leersia hexandra'' Swartz for removing Cr, Cu and Ni from electroplating wastewater.
''Environmental Technology'' in press. Its ability to absorb chromium in particular has been described as "extraordinary".[Zhang, X. H., et al. (2007)]
Chromium accumulation by the hyperaccumulator plant ''Leersia hexandra'' Swartz.
''Chemosphere'' 67(6), 1138-43.[Liu, J., et al. (2009)]
Subcellular distribution of chromium in accumulating plant ''Leersia hexandra'' Swartz.
''Plant and Soil'' 322(1-2), 187-95. It is considered to be a potential agent of phytoremediation
Phytoremediation technologies use living plants to clean up soil, air and water contaminated with hazardous contaminants. It is defined as "the use of green plants and the associated microorganisms, along with proper soil amendments and agronomi ...
in efforts to clean up metal-contaminated soils and water.[ Targets could include industrial ]wastewater
Wastewater is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of domestic, industri ...
, such as that discharged from electroplating
Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the redox, reduction of cations of that metal by means of a direct current, direct electric cur ...
factories,[ and the contaminated soils around such facilities.][
]
References
{{Taxonbar, from=Q3228992
Oryzoideae
Forages
Phytoremediation plants
Pantropical flora
Taxa named by Olof Swartz