Ventenata dubia (North Africa grass)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Risk of Introduction
- Habitat List
- Growth Stages
- Biology and Ecology
- Latitude/Altitude Ranges
- Air Temperature
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Impact Summary
- Economic Impact
- Environmental Impact
- Risk and Impact Factors
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Ventenata dubia (Leers) Coss. & Durieu
Preferred Common Name
- North Africa grass
Other Scientific Names
- Avena dubia Leers
- Avena fertilis All.
- Avena triaristata Vill.
- Festuca tenuis (Moench) Raspail
- Gaudinia tenuis (Moench) Trin.
- Heteranthus dubius (Leers) Thell.
- Heteranthus tenuis (Moench) Dumort.
- Trisetaria tenuis (Host) Baumg.
- Trisetum tenue (Moench) Roem. & Schult.
- Ventenata avenacea Koeler
- Ventenata bromoides Koeler
International Common Names
- English: hairgrass; North Africa grass; softbearded oat grass; wiregrass
- French: venténata fausse-avoine; venténate douteuse; venténatée douteuse
Local Common Names
- Germany: Schmielenhafer
Summary of InvasivenessTop of page
Ventenata dubia, commonly known as North Africa grass or wiregrass, is an annual grass native to Europe and North Africa. It is shallow-rooted, with narrow leaf blades, and has been able to invade both annual-dominated and perennial-dominated grasslands. Grasslands previously dominated by Taeniatherum caput-medusae and Bromus tectorum are being invaded and dominated by V. dubia in the USA, where it is considered a weed. Pasture and grass hay production systems have been dominated by V. dubia within the Pacific Northwest, USA, and it has invaded sagebrush-steppe communities. Estimated losses for pasture and grass hay in northern Idaho and eastern Washington state, USA, is over $20 million annually.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Monocotyledonae
- Order: Cyperales
- Family: Poaceae
- Genus: Ventenata
- Species: Ventenata dubia
Notes on Taxonomy and NomenclatureTop of page
The genus name, Ventenata, is associated with French botanist Pierre Ventenat (1757-1805) (Nature Conservancy, 2000). The genus was previously placed within the Avena genus (subtribe Aveninae) and resides within the subtribe Airinae.
There are eight species in the genus Ventenata (The Plant List, 2013): V. blanchei Boiss., V. dubia (Leers) Coss. & Durieu, V. eigiana (H. Scholz & Raus) Dogan, V. huber-morathii (Dogan) D. Heller, V. macra (Steven) Balansa ex Boiss., V. quercetorum Boiss. & Bal., V. sorgerae (Dogan) D. Heller, and V. subenervis Boiss. & Balansa.
V. dubia is often referred to as wiregrass because its hardened stems can become tangled around the swather of a mowing machine (Scheinost et al., 2008).
DescriptionTop of page
V. dubia is a tufted winter annual grass with shallow fibrous roots. The stem is erect, 1.5-7 dm, and appears smooth, although tiny hairs can be seen when magnified. The leaf ligule is 1-6 mm long and the blade is 1-3 mm wide. Inflorescences are tawny to pale yellow, open, panicle-like, 3-10 cm long. The branches often spread until they droop. Spikelets (10-15 mm long) are near the branch tips and are stalked. The glumes are lancelolate, and end in a sharp tip. The lemmas have bent awns arising from their backs, much like those of wild oats (Avena barbata, A. fatua). The upper 1-2 florets are bisexual. Adapted from Nature Conservancy (2000) and Hitchcock (1969).
DistributionTop of page
Native and introduced ranges are challenging to determine for a species like V. dubia that has not received much study. Many entries within the distribution list are from specimens which would not specify whether it is native or introduced. V. dubia is generally considered native to Europe, however, V. dubia in Essex, UK, has been reported as an introduced and invasive species (Copping, 1987). Generally it is considered rare and native in eastern Europe. Outside of Europe, it is considered native to Tunisia, Iran and Turkey.
V. dubia has been introduced widely across North America (BONAP, 2015), to states such as California, New York and Washington (BONAP, 2015; IUCN, 2015; USDA-NRCS, 2015). In Canada, it has also been introduced to Alberta, British Columbia, New Brunswick, Ontario and Quebec (Douglas et al., 1998; Newmaster et al., 1998; Hinds, 2000; Flora of North America Editorial Committee, 2007; Lavoie et al., 2012).
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.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Iran||Present||Hamzeh'ee et al., 2008||Gilan and Ardabil. North slopes, 1800 to 1871 m|
|Turkey||Present||Davis, 1985; IUCN, 2015|
|Canada||Present||Present based on regional distribution.|
|-Alberta||Present||Introduced||Flora of North America Editorial Committee, 2007; USDA-NRCS, 2015|
|-British Columbia||Present||Introduced||Douglas et al., 1998; USDA-NRCS, 2015|
|-New Brunswick||Present||Introduced||Hinds, 2000; USDA-NRCS, 2015|
|-Ontario||Present||Introduced||Newmaster et al., 1998; USDA-NRCS, 2015|
|-Quebec||Present||Introduced||Lavoie et al., 2012; USDA-NRCS, 2015|
|USA||Present||Present based on regional distribution.|
|-California||Present||Introduced||IUCN, 2015; USDA-NRCS, 2015|
|-Idaho||Present||Introduced||Invasive||BONAP, 2015; USDA-NRCS, 2015|
|-Maine||Present||Introduced||BONAP, 2015; USDA-NRCS, 2015|
|-Montana||Present||Introduced||Invasive||BONAP, 2015; USDA-NRCS, 2015|
|-New York||Present||Introduced||BONAP, 2015; USDA-NRCS, 2015|
|-Ohio||Present||Introduced||BONAP, 2015; USDA-NRCS, 2015|
|-Oregon||Present||Introduced||Invasive||BONAP, 2015; USDA-NRCS, 2015|
|-Utah||Present||Introduced||BONAP, 2015; USDA-NRCS, 2015|
|-Washington||Present||Introduced||1952||Invasive||BONAP, 2015; USDA-NRCS, 2015||Spokane|
|-Wisconsin||Present||Introduced||BONAP, 2015; USDA-NRCS, 2015|
|-Wyoming||Present||Introduced||Invasive||BONAP, 2015; USDA-NRCS, 2015|
|Austria||Present||BioCASE, 2015; IUCN, 2015||Recorded in 1923|
|Belgium||Present||BioCASE, 2015||Recorded in 1861|
|Bulgaria||Present||BioCASE, 2015; IUCN, 2015||Recorded in 2004|
|Czech Republic||Present||Native||Not invasive||Danihelka et al., 2012|
|Finland||Present||BioCASE, 2015||Recorded in 2002|
|France||Present||BioCASE, 2015; IUCN, 2015||Recorded in 1887|
|Germany||Present||Bergmeier, 1991; IUCN, 2015||Recorded in 1899|
|Greece||Present||BioCASE, 2015; IUCN, 2015||Recorded in 2012|
|Hungary||Present||Native||Not invasive||Simonkai, 1876; IUCN, 2015|
|Italy||Present||Native||Not invasive||Bicknell, 1896; IUCN, 2015|
|Moldova||Present||BioCASE, 2015||Recorded in 1966|
|Netherlands||Present||BioCASE, 2015||Recorded in 1935|
|Poland||Present||Native||Frey and Paszko, 1998|
|Portugal||Present||Native||Sequeira et al., 2011|
|Romania||Present||BioCASE, 2015||Recorded in 1913|
|Slovakia||Present||BioCASE, 2015||Recorded in 1933|
|Spain||Present||Becerra et al., 2002; IUCN, 2015||Recorded in 1962|
|Ukraine||Present||Native||Not invasive||Didukh et al., 2004|
Risk of IntroductionTop of page
V. dubia can be introduced via seed contamination, particularly in the USA where it is not subject to seed laws.
V. dubia can be found as a contaminant in Kentucky bluegrass, hay and annual crops (Sheinost et al., 2008).
Asian markets do not accept it as a contaminant in grass hay; therefore grass hay contaminated with V. dubia cannot be exported.
HabitatTop of page
V. dubia is found in annual and perennial grassland in US states such as Washington, Idaho and Oregon (Prather, 2014). It can also be found in sagebrush-steppe communities throughout the western US (Bansal et al., 2014).
Habitat ListTop of page
|Terrestrial – Managed||Cultivated / agricultural land||Present, no further details||Harmful (pest or invasive)|
|Cultivated / agricultural land||Present, no further details||Natural|
|Cultivated / agricultural land||Present, no further details||Productive/non-natural|
|Managed forests, plantations and orchards||Secondary/tolerated habitat||Natural|
|Managed grasslands (grazing systems)||Principal habitat||Harmful (pest or invasive)|
|Managed grasslands (grazing systems)||Principal habitat||Natural|
|Disturbed areas||Principal habitat||Harmful (pest or invasive)|
|Disturbed areas||Principal habitat||Natural|
|Rail / roadsides||Principal habitat||Harmful (pest or invasive)|
|Rail / roadsides||Principal habitat||Natural|
|Urban / peri-urban areas||Secondary/tolerated habitat||Natural|
|Terrestrial ‑ Natural / Semi-natural||Natural forests||Secondary/tolerated habitat||Natural|
|Natural grasslands||Principal habitat||Harmful (pest or invasive)|
|Riverbanks||Principal habitat||Harmful (pest or invasive)|
|Scrub / shrublands||Principal habitat||Harmful (pest or invasive)|
|Arid regions||Principal habitat||Harmful (pest or invasive)|
Growth StagesTop of page Flowering stage, Fruiting stage, Post-harvest, Pre-emergence, Seedling stage, Vegetative growing stage
Biology and EcologyTop of page
V. dubia is a diploid species with a chromosome number of 2n=14.
Physiology and Phenology
V. dubia flowers from June to August with 2 or 3 fertile florets per spikelet, according to The Nature Conservancy (2000) which describes American flora. Spikelets break up quickly after maturity and the lowest floret retains the glumes.
Germination takes place above 8°C when there is approximately 1.8 cm of precipitation (silt loam soil texture). In western North America, most germination occurs in autumn with a small percentage (less than 15%) of seedlings germinating in late winter and spring. The after-ripening requirement is longer than 30 days and less than 60 days. Cold stratification reduced germination from 87% when stored at 20°C, dropping to 28% and 35% when stored at 5°C for 5 or 10 days respectively. Using a base temperature of 7°C, emergence took place at 50 to 130 growing degree days (GDD). Emergence was affected by land use, with perennial grasslands in the Conservation Reserve Program and in timothy hay having shorter GDD. Rangeland was longer at 130 GDD. Stem elongation began at approximately 320 to 360 GDD and anthesis initiated after 360 to 500 GDD (Wallace at al., 2015).
ClimateTop of page
|BS - Steppe climate||Preferred||> 430mm and < 860mm annual precipitation|
|Cs - Warm temperate climate with dry summer||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers|
Latitude/Altitude RangesTop of page
|Latitude North (°N)||Latitude South (°S)||Altitude Lower (m)||Altitude Upper (m)|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Mean annual temperature (ºC)||2||19|
|Mean maximum temperature of hottest month (ºC)||31|
|Mean minimum temperature of coldest month (ºC)||-6|
RainfallTop of page
|Parameter||Lower limit||Upper limit||Description|
|Dry season duration||3||9||number of consecutive months with <40 mm rainfall|
|Mean annual rainfall||195||686||mm; lower/upper limits|
Natural enemiesTop of page
Notes on Natural EnemiesTop of page
V. dubia is rated as ‘least concern’ by the IUCN since it has no major threats at present (IUCN, 2015).
V. dubia is unpalatable to livestock once the stems harden after the panicles begin to emerge (Sheinost et al., 2008).
Means of Movement and DispersalTop of page
Within western North America, the primary pattern for dispersal is along roadways and trails (Lass and Prather, 2007). Dispersal likely is on vehicles since seeds are small and the pattern of dispersal is from road edge to adjacent lands (T Prather, University of Idaho, USA, personal communication, 2015).
Often the first places V. dubia is found is within areas that are saturated with water, typically because of an underlying restricted infiltration layer, for part of the spring (Anicito, 2013). V. dubia has been found as a contaminant in both hay fields and in grass fields grown for seed (Old and Callihan, 1987).
The long awns on its seed allow it to be spread by becoming attached to animals (Sheinost et al., 2008) and potentially vehicles and machinery.
Impact SummaryTop of page
Economic ImpactTop of page
In inland northwestern USA, V. dubia has resulted in the reduction of both grass hay production and grass stand life by as much as 50% and foreign export of infested hay is not possible. Overall yields are 20% lower because of V. dubia. Therefore farmers have had to change their practices and are trying various methods of control. Regional losses (in eastern Washington and northern Idaho, USA) are $6.7 million and ripple effects in the economy pose a $22 million negative impact (Prather, 2014).
V. dubia has a shallow root system which may make soil more susceptible to erosion. Its invasion leads to a decline in productivity and land value (Sheinost, 2008).
In Canada and the lower 48 states of the USA, V. dubia is considered a weed (Whitson et al., 1996).
Environmental ImpactTop of page
Impact on Biodiversity
V. dubia changed plant species composition within Conservation Reserve Program lands (CRP - a land conservation programme administered by the Farming Service Agency) when it made up more than 50% foliar cover. The plant community change then resulted in changes to insect abundance during the nesting period of swallows that were foraging within CRP. Furthermore, reproduction of tree swallows was lower in areas with more than 50% foliar cover of V. dubia compared to areas with less than 10% foliar cover of V. dubia (Mackey, 2014).
Within its current distribution in northern Idaho and eastern Washington, USA, V. dubia has largely replaced cheatgrass (Bromus tectorum) as the dominant annual grass. In Oregon, where distribution overlaps with medusahead (Taeniatherum caput-medusae), V. dubia has become the dominant plant in many instances.
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Highly adaptable to different environments
- Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
- Pioneering in disturbed areas
- Tolerant of shade
- Highly mobile locally
- Benefits from human association (i.e. it is a human commensal)
- Has propagules that can remain viable for more than one year
- Altered trophic level
- Changed gene pool/ selective loss of genotypes
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Monoculture formation
- Negatively impacts agriculture
- Negatively impacts cultural/traditional practices
- Negatively impacts forestry
- Negatively impacts animal health
- Negatively impacts livelihoods
- Reduced amenity values
- Reduced native biodiversity
- Threat to/ loss of endangered species
- Threat to/ loss of native species
- Damages animal/plant products
- Antagonistic (micro-organisms)
- Competition - monopolizing resources
- Competition - shading
- Pest and disease transmission
- Interaction with other invasive species
- Highly likely to be transported internationally accidentally
- Difficult to identify/detect as a commodity contaminant
- Difficult to identify/detect in the field
UsesTop of page
V. dubia has little value as a forage plant since it becomes unpalatable to livestock once the stems harden after the panicles begin to emerge (Sheinost et al., 2008).
Similarities to Other Species/ConditionsTop of page
Before seed formation, V. dubia looks very similar to Deschampsiacespitosa, and other Deschampsia species. The length of the ligule overlaps 2-13 mm for D. cespitosa, 1-8 mm for V. dubia. Both have narrow leaves; 1-4 mm vs 0.8-2.5 mm for D. cespitosa and V. dubia respectively. Generally, V.dubia has purple to reddish brown culm nodes. When flowers are present, both have awns; upper awns of V. dubia are geniculate but the awn of the first floret is not geniculate, so if the other florets are no longer on the plant it may be confused with D. cespitosa. The rachilla of D. cespitosa is hairy, generally glabrous in V. dubia.
Another similar species is P. bulbosa, which has purple to reddish brown nodes on the culms but the keeled leaf tip should prevent confusion on closer examination.
The Nature Conservancy (2000) describes V. dubia in relation to flora in the USA and note that it can be mistaken for the annual cheatgrass (Bromus tectorum) due to shared characteristics of open panicles and similar height. However, B. tectorum has awns which are straight rather than bent, 3-6 florets per spikelet rather than 2-3 and flowers earlier, from May to June.
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.
It may be possible to eliminate or severely reduce and infestation of V. dubia via three to four years of aggressive management, followed by monitoring, since the seed is viable for only one to three years (Sheinost et al., 2008; Pavek et al., 2011).
Mowing V. dubia multiple times before heading, until the soil is dry and V. dubia cannot grow, may prevent seed from being produced. However, once heads are present it is too difficult to mow since the stems are too tough and simply bend (Sheinost et al., 2008).
V. dubia has shown resistence against glyphosphate and sethoxydim but imazapic appears to be effective (Nature Conservancy, 2000; Scheinost et al., 2008).
Cultural control and sanitary measures
Maintaining a healthy stand of perennial vegetation can minimize invasion by V. dubia (Scheinost et al., 2008).
Control by utilization
Animals will not eat V. dubia directly but some reports say that animals eat it when in small amounts in hay.
Gaps in Knowledge/Research NeedsTop of page
Genetic analysis is required to determine native and introduced distributions.
ReferencesTop of page
Anicito KR, 2013. A holistic approach to Mima mound prairie restoration. Masters Thesis, 115. USA: Eastern Washington University.
Becerra M; Rojas JG; Perez A, 2002. New records of monocotyledons for granada province (nuevas citas de monocotiledoneas para la provincia de granada). Acta Botanica Malacitana, 26:284-286.
Bergmeier E, 1991. Dissemination and sociology of Ventenata dubia (Leers) Cosson in Hesse (Verbreitung und Soziologie von Ventenata dubia (Leers) Cosson in Hessen). Hessische Floristische Briefe, 40(3):33-45.
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Mackey AM, 2014. Developing a decision support tool for ventenata (Ventenata dubia) integrated pest management in the inland northwest. MS Thesis. USA: University of Idaho. http://vivo.nkn.uidaho.edu/individual/T1018920140601
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ContributorsTop of page
21/05/2015 Original text by:
Timothy Prather, University of Idaho, USA
Distribution MapsTop of page
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