Aira caryophyllea (silver hairgrass)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Biology and Ecology
- Means of Movement and Dispersal
- Economic Impact
- Environmental Impact
- Threatened Species
- Risk and Impact Factors
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Aira caryophyllea L.
Preferred Common Name
- silver hairgrass
Other Scientific Names
- Agrostis caryophyllea (L.) Salisb.
- Aira aggregata Timeroy ex Bor.
- Aira armoricana F. Albers
- Aira bachitii Hochst. ex C.E.Hubb.
- Aira baetica Trin.
- Aira canescens [Illegitimate] Host
- Aira caryophyllea Bertol
- Aira caryophyllea var. major Brongn.
- Aira caryophyllea var. major Ducommun
- Aira caryophyllea var. minor Brongn.
- Aira curta Jord. ex Boreau
- Aira duriuscula Poir.
- Aira edouardii Reut. ex Jouve
- Aira fioriana [Invalid] Sennen
- Aira hostii Steud.
- Aira latigluma Steud.
- Aira leersii [Invalid] Kunth
- Aira lensii Rchb.
- Aira lenzei Godr.
- Aira multicaulis Kunth
- Aira multiculmis Dumort.
- Aira nana [Invalid] Steud.
- Aira nebrodensis Lojac.
- Aira patulipes Jord. ex Boreau
- Aira plesiantha Jord. ex Boreau
- Aira purpureoargentea Gilib.
- Aira reverchonii Murb.
- Aira rigida [Invalid] Dulac
- Aira saburralis Jan ex Guss.
- Aira todari Ten. ex Tod.
- Aira todarii [Invalid] Tineo ex Ponzo
- Aira truncata [Invalid] Salzm. ex Trin.
- Airella caryophyllea (L.) Dumort.
- Airopsis caryophyllea (L.) Fr.
- Aspris caryophyllea (L.) Nash
- Avena caryophyllea (L.) Web.
- Avena caryophyllea Sibth. & Sm.
- Avena multiculmis (Dumort.) Nyman
- Avena multiculmis Dumort.
- Avena plesiantha (Jord. ex A. Boreau) Nyman
- Avenastrum caryophylleum (L.) Jess.
- Caryophyllea airoides Opiz
- Deschampsia baetica (Trin.) Willk. & Lange
- Fussia caryophyllea (L.) Schur
- Salmasia multiculmis (Dumort.) Bubani
- Salmasia vulgaris Bubani
Local Common Names
- : aira caryophyllée; cauche caryophyllée
- : silvery hair grass
- China: yin xu cao
- Germany: Nelken-Haferschile
- Sweden: vittatel
Summary of InvasivenessTop of page
A. caryophyllea is a small grass species native to Europe and North and East Africa that grows in nutrient-poor habitats. By growing in dense colonies it can out-compete native plants and prevent their establishment (PIER, 2013). Although it has become fairly widespread in Europe, North Africa and Asia, as well as in the regions where it has been introduced, such as North America and Australasia, it is not often considered seriously invasive. However, Weeds of Australia (2013) suggested that its potential negative impact may have been underestimated, and in Victoria and Western Australia A. caryophyllea is reported as an environmental weed.
The California Invasive Plant Inventory (Cal-IPC, 2006) commented that A. caryophyllea is widespread in grasslands in California but has had an apparently negligible impact. Using the Australasian Weed Risk Assessment to measure the plant’s possible impact in Florida, Gordon et al. (2008) gave it a score of 9, suggesting that it could be a risk, but not a very important one.
The species is not listed on the Global Invasive Species Database (ISSG, 2013).
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Monocotyledonae
- Order: Cyperales
- Family: Poaceae
- Genus: Aira
- Species: Aira caryophyllea
Notes on Taxonomy and NomenclatureTop of page
The genus Aira comprises 10 species native to the Mediterranean eastward to Iran, but species are widespread as weeds elsewhere (Mabberley, 1997). Some species are grown as ornamentals.
The Plant List (2013) gives a very long list of synonyms that have in the past been used for A. caryophyllea.
DescriptionTop of page
The following description is modified from Clayton et al. (2006):
Annual. Culms erect; 3–40(–55) cm long; 2–3-noded. Leaves mostly basal. Ligule an eciliate membrane; 2–5 mm long; erose; obtuse. Leaf-blades filiform; involute; 0.5–5 cm long; 0.3–1 mm wide. Leaf-blade surface scaberulous. Leaf-blade apex acute.
A panicle. Panicle open; ovate; 1–12 cm long; (2–)3.5–10(–14) cm wide. Panicle branches capillary; terete; smooth. Spikelets solitary. Fertile spikelets pedicelled. Pedicels filiform; terete; 1–10 mm long; tip pyriform.
Spikelets comprising 2 fertile florets; without rhachilla extension. Spikelets oblong to ovate; laterally compressed; 2.4–3.1 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes suppressed between florets (florets arising at about the same level). Floret callus pubescent.
Glumes persistent; similar; exceeding apex of florets; thinner than fertile lemma; shiny; gaping. Lower glume ovate; 2.4–3.1 mm long; 1 length of upper glume; membranous; 1-keeled; keeled above; 1–3 -veined. Lower glume primary vein scaberulous. Lower glume apex acute. Upper glume ovate; 2.4–3.1 mm long; 1.2 length of adjacent fertile lemma; membranous; 1-keeled; keeled above; 1–3-veined. Upper glume primary vein scaberulous. Upper glume apex acute.
Fertile lemma ovate; laterally compressed; lanceolate in profile; (1.8–)2–2.4(–2.6) mm long; cartilaginous; dark brown; without keel; 5 -veined. Lemma lateral veins obscure. Lemma surface scaberulous; rough above. Lemma margins involute; covering most of palea. Lemma apex dentate; 2-fid; awned; 1-awned. Principal lemma awn dorsal; arising 0.3–0.4 way up back of lemma; geniculate; 2.6–3.6 mm long overall; with twisted column. Palea elliptic; 0.7 length of lemma; cartilaginous; 2 -veined. Palea apex obtuse.
Lodicules 2; lanceolate; membranous. Anthers 3; 0.25–0.6 mm long. Stigmas 2; protandrous; laterally exserted.
Caryopsis with adherent pericarp; fusiform; isodiametric; biconvex; estipitate; without sulcus; 1 mm long; smooth; apex unappendaged. Embryo 0.2 length of caryopsis. Hilum punctiform. Endosperm farinose. Disseminule comprising a floret.
Plant TypeTop of page Annual
Grass / sedge
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.Last updated: 10 Jan 2020
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Cameroon||Present||CABI Data Mining (2011); USDA-ARS (2013)|
|Gabon||Present||Missouri Botanical Garden (2013)|
|South Africa||Present||Introduced||USDA-ARS (2013)||Eastern Cape, Free State, KwaZulu-Natal, Northern Cape, Western Cape|
|-Tibet||Present||Flora of China (2013)||Dry grassy places in mountains; ca. 3600 m. W. Xizang|
|India||Present||Missouri Botanical Garden (2013)|
|South Korea||Present||CABI Data Mining (2011)|
|France||Present||CABI Data Mining (2011); USDA-ARS (2013)|
|Greece||Present||Native||CABI (Undated)||Original citation: Royal Botanic Garden Edinburgh (2012)|
|Italy||Present||CABI Data Mining (2011); USDA-ARS (2013)|
|Latvia||Present||CABI Data Mining (2011)|
|Poland||Present, Few occurrences||Native||Nowak and Nowak (2011)|
|Romania||Present||CABI Data Mining (2011); CABI (Undated)|
|Russia||Present||CABI (Undated a)||Present based on regional distribution.|
|-Southern Russia||Present||Native||USDA-ARS (2013)|
|-Canary Islands||Present||Native||USDA-ARS (2013)|
|United Kingdom||Present||Native||USDA-ARS (2013)|
|-British Columbia||Present||Introduced||USDA-ARS (2013)|
|-Nova Scotia||Present||Introduced||USDA-ARS (2013)|
|Costa Rica||Present||Missouri Botanical Garden (2013)|
|United States||Present||Invasive||PIER (2013)|
|-District of Columbia||Present||Introduced||USDA-NRCS (2013)|
|-Hawaii||Present||Introduced||Invasive||PIER (2013); USDA-NRCS (2013)||Hawaii (Big Island), Kauai, Maui, Molokai, Oahu|
|-New Hampshire||Present||Introduced||USDA-NRCS (2013)|
|-New Jersey||Present||Introduced||USDA-NRCS (2013)|
|-New York||Present||Introduced||USDA-NRCS (2013)|
|-North Carolina||Present||Introduced||USDA-NRCS (2013)|
|-Oregon||Present||Introduced||Invasive||PIER (2013); USDA-NRCS (2013)|
|-South Carolina||Present||Introduced||USDA-NRCS (2013)|
|-Washington||Present||Introduced||Invasive||PIER (2013); USDA-NRCS (2013)|
|Australia||Present||Introduced||Invasive||PIER (2013); USDA-ARS (2013)|
|-New South Wales||Present, Widespread||Introduced||CABI (Undated)||Southern and central; Original citation: Weeds of Australia (2013)|
|-Northern Territory||Present, Widespread||Introduced||CABI (Undated);||Southern; Original citation: Weeds of Australia (2013)|
|-Queensland||Absent, Formerly present||CABI (Undated)||South eastern; Original citation: Weeds of Australia (2013)|
|-South Australia||Present, Localized||Introduced||CABI (Undated)||South eastern; Original citation: Weeds of Australia (2013)|
|-Tasmania||Present, Widespread||Introduced||CABI (Undated)||Original citation: Weeds of Australia (2013)|
|-Victoria||Present, Widespread||Introduced||CABI (Undated)||Original citation: Weeds of Australia (2013)|
|-Western Australia||Present, Widespread||Introduced||CABI (Undated)||South western; Original citation: Weeds of Australia (2013)|
|New Zealand||Present||Introduced||Invasive||PIER (2013); Edgar and Connor (2000)|
|Chile||Present||Introduced||Invasive||PIER (2013); USDA-ARS (2013)||Mainland and Isla Más a Tierra|
|Ecuador||Present||Introduced||Invasive||PIER (2013); USDA-ARS (2013)|
History of Introduction and SpreadTop of page
Along with many other invasive plant species, A. caryophyllea was presumably introduced to the Americas, Australia and elsewhere by European migrants who, travelling to these regions, took with them pasture seeds, hay and straw for their animals, and straw and other vegetation packing materials for their belongings. It was recorded as being introduced to New Zealand before 1870 (Esler, 1987) and into Australia in 1884 (Australia's Virtual Herbarium, 2013).
IntroductionsTop of page
|Introduced to||Introduced from||Year||Reason||Introduced by||Established in wild through||References||Notes|
|Natural reproduction||Continuous restocking|
|Australia||Europe||1884||Yes||No||Australia's Virtual Herbarium (2013)||New South Wales. Probably accidental|
|New Zealand||Europe||<1870||Yes||No||Esler (1987)||Aukland. Probably accidental|
Risk of IntroductionTop of page
Introductions of A. coryophllea are becoming less likely, due to modern phytosanitary measures, but inadvertent introductions via seeds attached to clothing, may still occur. Seed could also be transmitted to countries in legal imports of agricultural seed, but this should be prevented by regulation and inspections of seed imports.
HabitatTop of page
In its native range, A. caryophyllea is found in heaths, on rocks, dunes and in forests on sandy and generally acid soils that are not too nutrient-poor. Weber (2003; in PIER, 2013) described its habitat as: ‘coastal vegetation, heath- and woodland, riparian habitats, wetlands and rock outcrops. It is adapted to nutrient-poor habitats and grows in dense colonies, eliminating native vegetation and preventing the establishment of native plants’.
In California, A. caryophyllea is one of a number of annual species (often from the Mediterranean) that have largely displaced the original perennial native species (Heady, 1958). Continuous high intensity grazing by livestock is thought to have contributed to non-native plant dominance of these grasslands (Bartolome et al., 2004).
A. caryophyllea is widespread in grasslands in South Australia (Weeds of Australia, 2013), where it is predominantly found in disturbed sites, but also in open woodlands, coastal heathlands and floodplains. Grant and Koch (1997) investigated seedbanks in the soil of rehabilitated bauxite mines in jarrah (Eucalyptus marginata) forest in Western Australia and found that more than half of the topsoil seed reserve was dominated by weed seeds, predominantly A. caryophyllea seeds.
In Hawaii A. caryophyllea is a weed of coastal vegetation, heathlands, woodlands, riparian habitats, wetlands, rock outcrops, pastures, old lavafields and sub-alpine shrublands (Weeds of Australia, 2013).
Hubbard (1984) described its habitat in Britain, where it is native, as dry gravelly and sandy soils, short grassland, heaths and commons and open woodland, from low altitudes to 610 m in Scotland. Similarly, where it has been introduced to New Zealand, it usually occurs in dry, stony or sandy ground, or in disturbed sites, but rarely in damp ground at the margins of swamps or lagoons (Edgar and Connor, 2010).
The species is sometimes also found growing on the tops of stone walls (Biological Records Centre, 2013).
Habitat ListTop of page
Hosts/Species AffectedTop of page
Weeds of Australia (2013) reported that A. caryophyllea is a common component of the remnants of natural temperate grasslands in the southern tablelands region, an endangered ecological community in New South Wales and the Australian Capital Territories. A. caryophyllea and other similar species may be replacing or out-competing native annual or spring-flowering species here, and could be having a negative impact on native species richness and diversity.
Biology and EcologyTop of page
The chromosome number of A. caryophyllea is reported to be 2n = 14 (Hubbard, 1984).
A. caryophyllea is strictly an annual (or winter annual), germinating in autumn and flowering and setting seed in spring. Tiller number at low light and poor nutrient levels can be as low as about 8, but with better light and more nutrients it can be up to 36 (Pemadasa and Lovell, 1976). Once the apical meristem of a tiller is differentiated into flower primordial, further vegetative growth stops (Pemadasa and Lovell, 1976). Rozijn and Van Der Werf (1986) similarly found that growth in the vegetative phase is followed by a phase of almost solely reproductive growth. As the inflorescence emerged, green leaves began to die and root biomass decreased, presumably, as the authors speculated, because of the movement of assimilates to reproductive organs.
Physiology and Phenology
In California, Evans et al. (1974) collected seeds of A. caryophyllea from plots previously treated with paraquat and tested their germination under different conditions. They observed that, when moistened, the seeds (technically caryopses) moved convulsively over the soil surface as the 4-6 mm long geniculate awn straightened with sudden jerks. This forced the callus of the lemma into the soil surface where it was held by a ring of upward pointing hairs around the base of the lemma. They found no requirement of after-ripening. Optimum germination took place in cool to moderate (15-20oC) day conditions and cool (10-15oC) nights. Germination rate was high whether seeds were sown or buried in moist soil in pots.
In sand dunes on Anglesey, Wales, UK, Pemadasa and Lovell (1975) found that A. caryophyllea seeds were shed in June and July and germinated in mid-October. The seeds have a low level of innate dormancy. Attempts to germinate seeds at temperatures of 15 or 25oC apparently imposed dormancy. Fresh seeds in particular required high levels of continuous moisture in order to germinate successfully. As seed aged from 4 to 20 weeks after harvest, overall germination increased and temperature dependence declined. After 20 weeks' storage, seeds germinated quickly and well at temperatures of 10 to 25oC, and only a little more slowly at 5oC. This means that in the field, seeds shed in summer find conditions too warm and too dry for germination, and it is not until autumn, when temperatures are lower, when seeds are older and soil moisture greater, that conditions allow the seeds to germinate.
Light had no apparent effect on germination, but burial in sand reduced seed germination and seedling emergence: although some seeds (less than 30%) germinated when buried more than 1 cm deep, none of the resulting weak, small etiolated seedlings emerged successfully. However, the same authors found that when seeds were buried 3 cm deep in sand they could still germinate rapidly 4 months later when sown on moist filter paper. Despite this, Pamadasa and Lovell (1974b) found buried seeds at only one site out of ten samples taken from sand dunes.
The plants themselves are strictly annual and most seeds probably do not live in the soil for long, although a few may become deeply buried (as a result of animal or other disturbance) and may not then germinate until further disturbance occurs (Kotanen, 1996).
Population Size and Structure
In California, Bartolome (1979) found 58.7 A. caryophyllea seeds dm-1 in the top 6.4 cm of soil in autumn (before the rains) in one year, and 98.7 dm-1 the next year. As seeds gradually germinated throughout winter the number of plants increased to about 10 dm-1 in the first year and to over 50 dm-1 in the second year. Seed production from plants in the second year was estimated at 364 dm-1.
Pemadasa and Lovell (1974a) observed the poor growth of A. caryophyllea and other annual species on sand dunes and explored the effects of nutrients on vegetative growth, finding that nitrogen and potassium were especially important in increasing the number of tillers and their size, as well as total dry matter production. When increased levels of nitrogen and phosphorus were applied to plants, vegetative growth improved considerably. The authors found no effect of adding potassium, but speculated that this may be because potassium levels in the sand used in the experiment were already adequate. At lower levels of nitrogen, leaf development was hindered and leaf senescence hastened. Lower levels of phosphate also caused early leaf senescence even at the highest nitrogen concentration.
A. caryophyllea occurs in different environments and is therefore associated with many different species in different places. In California, for example, it is one component of annual grasslands that extend over an area of about 10 million ha, both in open grassland and as understorey in oak savannah and chaparral (Bartolome (1979). On sand dunes on Anglesey, Wales, UK, this species is associated with annuals such as Aira praecox, Cerastiumatrovirens, Erophila verna, Mibora minima and Vulpia membranacea (Pemadasa and Lovell, 1974b).
Although capable of growing in very dry, nutrient-impoverished habitats like sand dunes and on walls and in rock crevices, A. caryophyllea also responds well and grows better in the presence of adequate moisture and nutrients. Rozijn and Van Der Werf (1986) suggested that the species is mainly adapted to drought by being able to grow and set seed in a very short time, rather than being itself especially drought tolerant.
Means of Movement and DispersalTop of page
Natural Dispersal (Non-Biotic)
Although the seeds are small and could be dispersed by wind currents, Pemadasa and Lovell (1974b) suggested that the small size of mature plants acts against seed dispersal of more than about 25 cm.
Vector Transmission (Biotic)
Seeds may get caught in the fur, feathers or hair of animals and dispersed in that way. In south-east France, where it is native, Detrain and Pasteels (2000) observed that the harvester ant Messor barbarus harvested seeds of A. caryophyllea, but did so less frequently than expected from their natural availability. Harvesting of seeds by ants can sometimes lead to dispersal as well as consumption.
A. caryophyllea has been inadvertently introduced in the past when its seeds were taken to North America and Australasia. This was probably the result of seeds being carried in the fur, feathers or wool of animals being transported to European colonies, or in animal feed, bedding, grass seed or vegetation packing materials.
Intentional introduction is unlikely as the grass is small and produces little fodder. It has never been deliberately introduced for fodder anywhere (Hubbard, 1984).
Economic ImpactTop of page
The economic impacts of A. caryophyllea are probably minimal, and the economic value of controlling A. cayophyllea is hard to argue either way; although it probably provides some low-quality fodder for grazing animals, it may replace higher value species which could provide much better fodder. It also enters the flowering stage early in the spring and then produces no more vegetative growth (Pemadasa and Lovell, 1976). Pitt and Heady (1979) describe the species as ‘a diminutive, low-forage-value grass’.
This species is of some concern to environmental groups and land managers in the Australian states of Western Australia and Victoria (Weeds of Australia, 2013), as it is invasive in several native communities as well as pastures and other grasslands.
Environmental ImpactTop of page
Individual plants of A. caryophyllea are small, but population density can be high, and according to Weeds of Australia (2013) the plant could exclude native ground cover and restrict germination of desirable plants:
In Victoria, A. caryophila is considered a serious threat to some vegetation formations, as it is common in a variety of native plant communities, including damp and heathy herb-rich woodlands in the Wimmera bioregion, as well as ‘lateritic woodlands in the Goldfields bioregion and estuarine wetlands', and 'damp herb-rich woodlands and dry valley forests in the Gippsland bioregion’ (Weeds of Australia, 2013).
It is also thought to be a moderately important threat in Western Australia, where it has invaded bushland in good to excellent condition and is thought to have a wide potential distribution (Weeds of Australia, 2013). However, it is only one of a group of introduced invasive species growing in these areas.
In California, this species is but one of a wide range of introduced species which have taken over much of the native grasslands (Heady, 1958).
Threatened SpeciesTop of page
|Threatened Species||Conservation Status||Where Threatened||Mechanism||References||Notes|
|Schiedea hookeri (sprawling schiedea)||CR (IUCN red list: Critically endangered); USA ESA listing as endangered species||Hawaii||Competition - monopolizing resources; Ecosystem change / habitat alteration||US Fish and Wildlife Service, 2011|
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Has a broad native range
- Abundant in its native range
- Is a habitat generalist
- Pioneering in disturbed areas
- Fast growing
- Has high reproductive potential
- Has propagules that can remain viable for more than one year
- Competition - monopolizing resources
UsesTop of page
Where plants occur in grazed pastures, they contribute some fodder in winter, but dry out and then die out in spring or early in summer.
Similarities to Other Species/ConditionsTop of page
A. caryophyllea is very similar in general appearance and occurs in similar habitats to Aira praecox, but can be distinguished by its very loose panicles, with its spikelets in loose clusters at the tips of branches, and by the rough leaf-sheaths. In addition, A. praecox attains a height of 2 to 20 cm, whilst A. caryophyllea reaches 3 to 40 cm (Hubbard, 1984).
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Modern phytosanitary regulations and inspections should prevent further spread of A. cayophyllea to new countries in grass seed or as a contaminant on agricultural machinery; however, seeds could easily enter a country on the clothing or luggage of travellers.
Physical control of individual plants or small numbers of plants can easily be achieved, and larger infestations could be removed by ploughing and inverting the top layers of soil. However, drilling or oversowing with suitable pasture species would then be needed to establish a sward that could prevent reinvasion by A. caryophyllea.
When moving machinery from affected areas to those where A. caryophyllea does not yet occur, care should be taken to ensure that no seed is carried from place to place. The same applies to footwear and sports equipment.
Herbicides like glyphosate give good control of A. caryophyllea, but unless more competitive species well-suited to the habitat are established in its place, it will reinvade very quickly.
Control by Utilization
Murphy and Crampton (1964) described A. caryophyllea as an undesirable forage grass in Californian woodland (presumably on the grounds of its low forage production), but also commented that it did not invade grasslands following the felling of blue oaks (Quercus douglasii), removed to improve forage quality. Grazing by grey kangaroos (Macropus giganteus) reduced the cover of A. caryophyllea in a nature reserve in Australian Capital Territories (Neave and Tanton, 1989).
ReferencesTop of page
Australian Weeds Committtee, 2013. Weeds of Australia. Canberra, Australia: Australian Weeds Committtee. http://www.weeds.org.au/
Australia's Virtual Herbarium, 2013. Aira caryophyllea: silver-haired grass. Australia's Virtual Herbarium, Council of Heads of Australasian Herbaria (CHAH), Canberra, Australia. http://avh.ala.org.au/occurrences/search?taxa=aira+caryophyllea#mapView
Bartolome JW, 1979. Germination and seedling establishment in Californian annual grassland. Journal of Ecology, 67(1):273-281.
Biological Records Centre, 2013. Online Atlas of the British and Irish flora. Wallingford, UK: Biological Records Centre. http://www.brc.ac.uk/plantatlas/
Cal-IPC, 2006. California Invasive Plant Inventory. Berkeley, California, USA: Cal-IPC (California Invasive Plant Council). http://www.cal-ipc.org/
Clayton WD, Vorontsova MS, Harman KT, Williamson H, 2006. GrassBase - The Online World Grass Flora. UK: The Board of Trustees, Royal Botanic Gardens, Kew. http://www.kew.org/data/grasses-db.html
Flora of China, 2013. Flora of China. http://www.efloras.org/
Gordon DR, Onderdonk DA, Fox AM, Stocker RK, Gantz C, 2008. Predicting invasive plants in Florida using the Australian weed risk assessment. Invasive Plant Science and Management, 1(2):178-195. http://www.wssa.net
Hubbard CE, 1984. Grasses: A Guide to their Structure, Identification, Uses and Distribution in the British Isles. Harmondsworth, Middlesex, UK: Penguin Books Limited, 476 pp.
ISSG, 2013. Global Invasive Species Database (GISD). Invasive Species Specialist Group of the IUCN Species Survival Commission. http://www.issg.org/database/welcome/
ITIS, 2013. Integrated Taxonomic Information System (ITIS). Washington, DC, USA: Smithsonian Institution/NMNH. http://www.itis.gov/
Mabberley DJ, 1997. The Plant Book: A Portable Dictionary of the Vascular Plants. 2nd edition. Cambridge, UK: Cambridge University Press.
Missouri Botanical Garden, 2013. Tropicos database. St Louis, USA: Missouri Botanical Garden. http://www.tropicos.org/
Mito T, Uesugi T, 2004. Invasive alien species in Japan: the status quo and the new regulation for prevention of their adverse effects. Global Environmental Research, 8(2):171-191.
Neave HM, Tanton MT, 1989. The effects of grazing by kangaroos and rabbits on the vegetation and the habitat of other fauna in the Tidbinbilla Nature Reserve, Australian Capital Territory. Australian Wildlife Research, 16(3):337-351.
Nowak A, Nowak S, 2011. Extensively used ground roads support the maintenance of Aira caryophyllea L. (Poaceae) in Opole Silesia. Opole Scientific Society Nature Journal, 44:25-29.
PIER, 2013. Pacific Islands Ecosystems at Risk. Honolulu, Hawaii, USA: HEAR, University of Hawaii. http://www.hear.org/pier/index.html
Royal Botanic Garden Edinburgh, 2013. Flora Europaea, Database of European Plants (ESFEDS). Edinburgh, UK: Royal Botanic Garden Edinburgh. http://rbg-web2.rbge.org.uk/FE/fe.html
The Plant List, 2013. The Plant List: a working list of all plant species. Version 1.1. London, UK: Royal Botanic Gardens, Kew. http://www.theplantlist.org
USDA-ARS, 2013. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx
USDA-NRCS, 2013. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/
CABI Data Mining, 2011. Invasive Species Databases.,
CABI, Undated. Compendium record. Wallingford, UK: CABI
CABI, Undated a. CABI Compendium: Status inferred from regional distribution. Wallingford, UK: CABI
CABI, Undated b. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Flora of China, 2013. Flora of China., http://www.efloras.org/
Missouri Botanical Garden, 2013. Tropicos database., St Louis, USA: Missouri Botanical Garden. http://www.tropicos.org/
Nowak A, Nowak S, 2011. Extensively used ground roads support the maintenance of Aira caryophyllea L. (Poaceae) in Opole Silesia. In: Opole Scientific Society Nature Journal, 44 25-29.
PIER, 2013. Pacific Islands Ecosystems at Risk., Honolulu, Hawaii, USA: HEAR, University of Hawaii. http://www.hear.org/pier/index.html
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ContributorsTop of page
20/05/13: Original text by:
Ian Popay, consultant, New Zealand, with the support of Landcare Research.
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