Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Bromus hordeaceus
(soft brome)

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Datasheet

Bromus hordeaceus (soft brome)

Summary

  • Last modified
  • 06 November 2018
  • Datasheet Type(s)
  • Invasive Species
  • Preferred Scientific Name
  • Bromus hordeaceus
  • Preferred Common Name
  • soft brome
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Monocotyledonae
  • Summary of Invasiveness
  • B. hordeaceus is a grass species native to Europe. It has several features shared by successful invasive species including a short life cycle as an annual species and an association with a predominantl...

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Pictures

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PictureTitleCaptionCopyright
Bromus hordeaceus (soft chess); single plant. Old Kula Hwy, Maui. April 18, 2003
TitleSingle plant
CaptionBromus hordeaceus (soft chess); single plant. Old Kula Hwy, Maui. April 18, 2003
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Bromus hordeaceus (soft chess); single plant. Old Kula Hwy, Maui. April 18, 2003
Single plantBromus hordeaceus (soft chess); single plant. Old Kula Hwy, Maui. April 18, 2003©Forest Starr & Kim Starr - CC BY 4.0
Bromus hordeaceus (soft chess); seedheads. Kula, Maui. June 28, 2011
TitleSeedheads
CaptionBromus hordeaceus (soft chess); seedheads. Kula, Maui. June 28, 2011
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Bromus hordeaceus (soft chess); seedheads. Kula, Maui. June 28, 2011
SeedheadsBromus hordeaceus (soft chess); seedheads. Kula, Maui. June 28, 2011©Forest Starr & Kim Starr - CC BY 4.0

Identity

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Preferred Scientific Name

  • Bromus hordeaceus L.

Preferred Common Name

  • soft brome

Other Scientific Names

  • Avena mollis (L.) Salisb.
  • Bromus hordeaceus subsp. hordeaceus
  • Bromus molliformis J. Lloyd
  • Bromus mollis L.
  • Bromus simplicissimus Ces.
  • Forasaccus mollis (L.) Bubani
  • Serrafalcus mollis (L.) Parl.
  • Serrafalcus rigens Samp.

International Common Names

  • English: barley brome; bull grass; common soft brome; least soft brome; lop grass; sand soft brome; soft brome; soft brome(grass); soft chess; tender brome
  • Spanish: bromo blando; bromo suelto
  • French: brome fausse orge; brome mou
  • Chinese: mao que mai

Local Common Names

  • Czech Republic: sverep mékký
  • Denmark: blød hejre
  • Finland: mäkikattara; nurmi-kattara
  • Germany: weiche trespe
  • Greece: bromos pyknos
  • Hungary: puha rozsnok
  • Italy: forasacco peloso; spigolina
  • Japan: hama chahiki
  • Netherlands: zachte dravik
  • New Zealand: goosegrass
  • Norway: lodnefaks
  • Poland: mechka kostrjawa; stoklosa miekka
  • Portugal: bromo-mole
  • Russian Federation: koster miagkii (Koster mjagkij)
  • Slovenia: zachte dravik
  • South Africa: sagtebromus
  • Sweden: luddlosta
  • Turkey: yumusak brom

EPPO code

  • BROMO (Bromus mollis)

Summary of Invasiveness

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B. hordeaceus is a grass species native to Europe. It has several features shared by successful invasive species including a short life cycle as an annual species and an association with a predominantly autogamous breeding system. In addition to this, complex polyploidy gives rise to a diversity which provides adventive populations with an enhanced adaptive capacity, allowing B. hordeaceus to respond to new selection pressures (Ainouche et al., 1999). B. hordeaceus has been introduced into parts of North and South America and Australia. It is a weed of crop fields, grasslands, orchards and turf where it competes with native vegetation and monopolizes resources.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Monocotyledonae
  •                     Order: Cyperales
  •                         Family: Poaceae
  •                             Genus: Bromus
  •                                 Species: Bromus hordeaceus

Notes on Taxonomy and Nomenclature

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Bromus, a weedy mimic of the cereal crops Triticum and Secale, is a taxonomically difficult genus with several unresolved species complexes complicated by a wide-ranging variety of opinions on taxonomic nomenclature (Smith, 1968; Smith, 1983; Scholz, 2008; Williams et al., 2011).

The nomenclature is confused by additional combinations which, though similar in appearance actually refer to a separate species of Bromus. For example Bromus hordeaceus var. intermedius is an accepted synonym for Bromus intermedius (Tropicos, 2013).

B. hordeaceus is a member of the family Poaceae (Watson and Dallwitz, 1992) and assigned to one of the seven sections, Bromus sect. bromus.

The Plant List (2015) details a total of 99 synonyms for B. hordeaceus. B. mollis is a frequent synonym used in European treatments, while B. hordeaceus is used elsewhere, especially in the Americas. Four subspecies are of B. hordeaceus have been described in the United States that, for the most part, are morphologically distinct (Barkworth et al., 2007). No evidence, however, has been found of genetic differentiation among them (Ainouche et al., 1999). These subspecies are B. hordeaceus L. subsp. hordeaceus, B. hordeaceus subsp. molliformis, B. hordeaceus subsp. pseudothominei and B. hordeaceus subsp. thominei. Bromus hordeaceus ssp. divaricatus has also been listed as a subspecies (ITIS, 2013).

Bromus: from Classical Greek βρομóς (bromos), a grass eaten by cattle, oats; and hordeaceus: from Classical Latin of or relating to barley.

Description

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Plants annual or biennial. Culms 2–70 cm, erect or ascending. Lower sheaths densely, often retrorsely pilose; upper sheaths pubescent or glabrous; ligules 1–1.5 mm, hairy, obtuse, erose; blades 2–19 cm long, 1–4 mm wide, abaxial surfaces glabrous or hairy, adaxial surfaces hairy. Panicles 1–13 cm long, 1–4 cm wide, erect, usually ovoid, open, becoming dense, occasionally reduced to 1 or 2 spikelets; branches shorter than the spikelets, ascending to erect, straight or almost so. Spikelets (11)14–20(23) mm, lanceolate, terete to moderately laterally compressed; florets 5–10, bases concealed at maturity; rachilla internodes concealed at maturity. Glumes pilose or glabrous; lower glumes 5–7 mm, 3–5-veined; upper glumes 6.5–8 mm, 5–7-veined; lemmas 6.5–11 mm long, 3–5 mm wide, lanceolate, chartaceous, antrorsely pilose to pubescent, or glabrous proximally or throughout, 7–9-veined, lateral veins prominently ribbed, rounded over the midvein, hyaline margins abruptly or bluntly angled, not inrolled at maturity, apices acute, bifid, teeth shorter than 1 mm; awns 6–8 mm, usually arising less than 1.5 mm below the lemma apices, straight to recurved at maturity; anthers 0.6–1.5 mm. Caryopses equaling or shorter than the paleas, thin, weakly inrolled to flat (Barkworth et al., 2007).

Plant Type

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Distribution

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B. hordeaceus is native to the Mediterranean basin and, more widely, Europe in general. B. hordeaceus has been introduced into the Americas, Eurasia, South Africa, Australasia, and some islands of the Pacific (Williams et al., 2011).

B. hordeaceus, a native species in the Czech Republic according to many treatments, is considered invasive in the Catalogue of alien plants of the Czech Republic (Pyšek et al., 2002).

Distribution Table

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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/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

ArmeniaPresentEuro+Med, 2013Possible introduction through cultivation
AzerbaijanPresentNativeEuro+Med, 2013; USDA-ARS, 2013Possible introduction through cultivation
ChinaPresentIntroducedTropicos, 2013
-GansuPresentIntroducedFlora of China Editorial Committee, 2006
-HebeiPresentIntroducedFlora of China Editorial Committee, 2006
-NingxiaPresentIntroduced Invasive Wittig et al., 2000
-QinghaiPresentIntroducedFlora of China Editorial Committee, 2006
-XinjiangPresentIntroducedFlora of China Editorial Committee, 2006
Georgia (Republic of)PresentIntroducedGBIF, 2012
IranPresentIntroducedUSDA-ARS, 2013Ahvaz-Dizful road, via Shush and Andimishk
IraqPresentIntroducedUSDA-ARS, 2013South side of Riber Zab, Mosul-Erbil road; 57 km. North of Mosul; 70 km. East of Kirkuk
JapanPresentIntroducedGBIF, 2012Hyogo; Okayama Prefecture; Nara; Kanagawa Prefecture; Akita
KyrgyzstanPresenteMonocot, 2013
LebanonPresentNativeGBIF, 2012
PakistanPresentIntroducedFlora of China Editorial Committee, 2006
TaiwanPresentIntroducedFlora of China Editorial Committee, 2006; MingJer et al., 2006
TajikistanPresenteMonocot, 2013
TurkeyPresenteMonocot, 2013
TurkmenistanPresenteMonocot, 2013
UzbekistanPresenteMonocot, 2013

Africa

AlgeriaPresentNativeGBIF, 2012; USDA-ARS, 2013Oued Imbert
EgyptPresenteMonocot, 2013
LibyaPresentNativeeMonocot, 2013; USDA-ARS, 2013
MoroccoPresentNative Not invasive Hamal et al., 2001; USDA-ARS, 201317 miles Northwest of Qugda
South AfricaPresentIntroducedRussell et al., 1987; GBIF, 2012
Spain
-Canary IslandsPresenteMonocot, 2013
TunisiaPresentNativeUSDA-ARS, 2013

North America

CanadaPresentIntroducedTropicos, 2013
-AlbertaPresentIntroducedBrouillet et al., 2006
-British ColumbiaPresentIntroducedBrouillet et al., 2006; GBIF, 2012
-New BrunswickPresentIntroducedBrouillet et al., 2006
-Newfoundland and LabradorPresentIntroducedBrouillet et al., 2006
-Northwest TerritoriesPresentIntroducedBrouillet et al., 2006
-Nova ScotiaPresentIntroducedBrouillet et al., 2006
-OntarioPresentIntroducedBrouillet et al., 2006
-Prince Edward IslandPresentIntroducedBrouillet et al., 2006
-QuebecPresentIntroducedBrouillet et al., 2006
-Yukon TerritoryPresentIntroducedBrouillet et al., 2006
GreenlandPresentIntroducedTropicos, 2013
MexicoPresentIntroducedTropicos, 2013
Saint Pierre and MiquelonPresentIntroducedBrouillet et al., 2006
USAWidespreadIntroducedTropicos, 2013
-AlaskaPresentIntroducedGeological Survey, 2013Latitude: 58.3042; Longitude: -134.408
-ArizonaPresentIntroducedUSDA-NRCS, 2013
-ArkansasPresentIntroducedUSDA-NRCS, 2013
-CaliforniaWidespreadIntroducedGeological Survey, 2013
-ColoradoPresentIntroducedUSDA-NRCS, 2013
-ConnecticutPresentIntroducedUSDA-NRCS, 2013
-DelawarePresentIntroducedUSDA-NRCS, 2013
-District of ColumbiaAbsent, formerly presentIntroducedGeological Survey, 2013
-HawaiiWidespreadIntroduced Invasive PIER, 2012Kauai; Maui; Hawaii; Molokai; Oahu
-IdahoPresentIntroducedUSDA-NRCS, 2013
-IllinoisPresentIntroducedUSDA-NRCS, 2013
-IndianaPresentIntroducedUSDA-NRCS, 2013
-IowaPresentIntroducedUSDA-NRCS, 2013
-KansasPresentIntroducedUSDA-NRCS, 2013
-KentuckyPresentIntroducedUSDA-NRCS, 2013
-LouisianaPresentIntroducedGeological Survey, 2013Ouachita County
-MainePresentIntroducedUSDA-NRCS, 2013
-MarylandPresentIntroducedUSDA-NRCS, 2013
-MassachusettsPresentIntroducedUSDA-NRCS, 2013
-MichiganPresentIntroducedUSDA-NRCS, 2013
-MinnesotaPresentIntroducedUSDA-NRCS, 2013
-MississippiPresentIntroducedUSDA-NRCS, 2013
-MissouriPresentIntroducedUSDA-NRCS, 2013
-MontanaPresentIntroducedUSDA-NRCS, 2013
-NebraskaPresentIntroducedUSDA-NRCS, 2013
-NevadaPresentIntroducedUSDA-NRCS, 2013
-New HampshirePresentIntroducedUSDA-NRCS, 2013
-New JerseyPresentIntroducedUSDA-NRCS, 2013
-New MexicoPresentIntroducedUSDA-NRCS, 2013
-New YorkPresentIntroducedUSDA-NRCS, 2013
-North CarolinaPresentIntroducedUSDA-NRCS, 2013
-North DakotaPresentIntroducedUSDA-NRCS, 2013
-OhioPresentIntroducedUSDA-NRCS, 2013
-OklahomaPresentIntroducedUSDA-NRCS, 2013
-OregonPresentIntroducedUSDA-NRCS, 2013
-PennsylvaniaPresentIntroducedUSDA-NRCS, 2013
-Rhode IslandPresentIntroducedUSDA-NRCS, 2013
-South CarolinaPresentIntroducedUSDA-NRCS, 2013
-South DakotaPresentIntroducedUSDA-NRCS, 2013
-TennesseePresentIntroducedUSDA-NRCS, 2013
-TexasPresentIntroducedUSDA-NRCS, 2013
-UtahPresentIntroducedUSDA-NRCS, 2013
-VermontPresentIntroducedUSDA-NRCS, 2013
-VirginiaPresentIntroducedUSDA-NRCS, 2013
-WashingtonPresentIntroducedUSDA-NRCS, 2013
-West VirginiaAbsent, formerly presentIntroducedMillspaugh and Nuttall, 1896
-WisconsinPresentIntroducedUSDA-NRCS, 2013
-WyomingPresentIntroducedUSDA-NRCS, 2013

South America

ArgentinaPresentIntroducedPlanchuelo and Peterson, 2000; GBIF, 2012; Tropicos, 2013
BrazilPresentIntroducedTropicos, 2013
-Rio Grande do SulPresentIntroducedGBIF, 2012São Francisco de Paula
ChilePresentIntroducedGBIF, 2012; PIER, 2012; Tropicos, 2013
UruguayPresentIntroducedTropicos, 2013

Europe

AlbaniaPresentNative Not invasive GBIF, 2012
AndorraPresentNative Not invasive GBIF, 2012
AustriaWidespreadNative Not invasive GBIF, 2012
BelarusPresentNative Not invasive USDA-ARS, 2013
BelgiumWidespreadNative Not invasive GBIF, 2012
Bosnia-HercegovinaPresentNative Not invasive GBIF, 2012
BulgariaPresentNative Not invasive GBIF, 2012
CroatiaWidespreadNative Not invasive GBIF, 2012
CyprusPresenteMonocot, 2013
DenmarkWidespreadNative Not invasive GBIF, 2012Zealand; Sjaelland; Nordjylland; Vestjylland; Østjylland; Sjælland; jælland Fyn; Jylland
EstoniaPresenteMonocot, 2013
Faroe IslandsPresentIntroducedeMonocot, 2013
FinlandWidespreadNative Not invasive GBIF, 2012
FranceWidespreadNative Not invasive GBIF, 2012
-CorsicaPresenteMonocot, 2013
GermanyWidespreadNative Not invasive GBIF, 2012
GreeceWidespreadNative Not invasive GBIF, 2012
HungaryWidespreadNative Not invasive Solymosi, 1989; GBIF, 2012
IcelandPresenteMonocot, 2013
IrelandWidespreadNative Not invasive GBIF, 2012
ItalyWidespreadNative Not invasive GBIF, 2012
LatviaPresentNative Not invasive eMonocot, 2013
LithuaniaPresenteMonocot, 2013
LuxembourgWidespreadNative Not invasive GBIF, 2012
MaltaPresentNative Not invasive Euro+Med, 2013
MoldovaPresentNative Not invasive USDA-ARS, 2013
NetherlandsWidespreadNative Not invasive GBIF, 2012
NorwayPresentNative Not invasive GBIF, 2012; Tropicos, 2013
PolandWidespreadNative Not invasive GBIF, 2012
PortugalWidespreadNative Not invasive Acedo and Llamas, 1999
-AzoresPresentNative Not invasive Euro+Med, 2013
-MadeiraPresentNativeeMonocot, 2013; USDA-ARS, 2013
RomaniaPresentNative Not invasive GBIF, 2012
Russian FederationPresentNative Not invasive Flora of China Editorial Committee, 2006; GBIF, 2012
-Central RussiaPresenteMonocot, 2013
-Western SiberiaPresenteMonocot, 2013
SerbiaPresentNativeUSDA-ARS, 2013North slope of Shar Planinna
SlovakiaWidespreadNative Not invasive GBIF, 2012
SloveniaPresentNative Not invasive Euro+Med, 2013
SpainWidespreadNative Not invasive Acedo and Llamas, 1999
-Balearic IslandsPresenteMonocot, 2013
SwedenWidespreadNative Not invasive GBIF, 2012
SwitzerlandPresentNativeUSDA-ARS, 2013
UKPresentNative Not invasive GBIF, 2012; Tropicos, 2013
UkrainePresenteMonocot, 2013

Oceania

AustraliaWidespreadIntroduced Invasive GBIF, 2012'Melaleuca' Blackmans Bay; Bruny ISland; Big Chalky Island. [Off west coast of Flinders Island, NE of Whitemark]; Mount Chappell Island; Preservation Island; Woody Island; Swan Island, near Cape Portland; Near airstrip.Hogan's [Hogan] Island; Hogans [Hogan] Group. Kents Group; Deal Island, Browns, Bay. 2 km NW from Port Macdonnell; Port Fairy; Jacks Beach Reserve; Western Port Bay; Flinders Island.
New ZealandPresentIntroduced Invasive PIER, 2012Kermadec Islands
Norfolk IslandPresentIntroduced Invasive PIER, 2012

Habitat

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B. hordeaceus is a graminoid found in crop fields, meadows, and annual grassland communities (Howard, 1998; FAO, 2013). In California and Oregon, B. hordeaceus is often a major component of annual grassland vegetation (Shock et al., 1984; Howard, 1998; Stapanian et al., 1998).

B. hordeaceus prefers a climate with relatively mild winters and very warm summers; however it adapts well to climatic variations. Dry Mediterranean climates are most favourable to B. hordeaceus (Howard, 1998). B. hordeaceus maximizes growth with moderate spring rainfall (-7 bar water regime) (Ewing and Menke, 1983). B. hordeaceus grows best on drained to dry soils; seed germination is significantly increased on decomposed granite as compared to organic matter such as straw (Howard, 1998).

Habitat List

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CategoryHabitatPresenceStatus
Littoral
Coastal areas Present, no further details
Coastal dunes Secondary/tolerated habitat
Terrestrial-managed
Cultivated / agricultural land Principal habitat
Disturbed areas Principal habitat
Industrial / intensive livestock production systems Principal habitat
Managed forests, plantations and orchards Principal habitat
Managed grasslands (grazing systems) Principal habitat
Rail / roadsides Principal habitat
Urban / peri-urban areas Secondary/tolerated habitat
Terrestrial-natural/semi-natural
Arid regions Present, no further details
Deserts Present, no further details
Natural forests Present, no further details
Natural grasslands Secondary/tolerated habitat
Riverbanks Secondary/tolerated habitat
Rocky areas / lava flows Present, no further details
Scrub / shrublands Present, no further details

Host Plants and Other Plants Affected

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Growth Stages

Top of page Post-harvest, Pre-emergence, Seedling stage, Vegetative growing stage

Biology and Ecology

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Genetics

Chromosome number: 2n = 28 (Ainouche et al., 1999; Lövkvist and Hultgård, 1999; Tropicos, 2013).

Reproductive Biology

B. hordeaceus is a mostly self-pollinating, autogamous annual (Howard, 1998). Establishment of B. hordeaceus from seed is limited by freezing temperature (Howard, 1998). B. hordeaceus germinates when sown on the surface with rates decreasing significantly when buried more than 2 cm deep (MingJer et al., 2006; Jensen, 2009). The seed bank of B. hordeaceus is most viable during the first year with most germination taking place within 13 months of seed dispersal. Some seeds however can persist for at least five years (Jensen, 2009). A study in New Zealand, on the other hand, found that more than 80% of the seeds of B. hordeaceus emerged within the first couple of months after planting, with full germination achieved by spring. Seed burial at depths from 1 to 20 cm did not significantly affect germination. Seedling establishment and vigour, however, were reduced with seed depth (Dastgheib and Poole, 2010).

Physiology and Phenology

B. hordeaceus has a C3 photosynthetic pathway (Grass Phylogeny Working Group et al., 2001).

Atmospheric C/N ratio changes due to increase in C02 may decrease water stress and lengthen the growing season for B. hordeaceus (Larigauderie et al., 1988).

B. hordeaceus is highly adaptive showing genetic differences and variation in response to landscape change through the addition of nutrients from fertilizers and the repeated removal of biomass through grazing or mowing (Völler et al., 2013).

B. hordeaceus produces 1,108.86 pollen grains per flower; 221.10 flowers per inflorescence; and 245,176 pollen grains per inflorescence (Prieto-Baena et al., 2003).

Germination of B. hordeaceus is influenced positively by a specific exposure range to light with decreasing germination rates at longer exposures. Potassium nitrate promoted germination significantly, but did not interact significantly with experimental light regimes (Ellis et al., 1986). B. hordeaceus seed dormancy is minimized when left undisturbed on soil surfaces and exposed to warmer temperatures (Clarke et al., 2000).

Allelic variation at the Adh-lb locus in B. hordeaceus may be under selective control (Lönn, 1993). 

Environmental Requirements

B. hordeaceus prefers a climate with relatively mild winters and very warm summers; however it adapts well to climatic variations. Dry Mediterranean climates are most favourable to B. hordeaceus (Howard, 1998). B. hordeaceus maximizes growth with moderate spring rainfall (-7 bar water regime) (Ewing and Menke, 1983). B. hordeaceus grows best on drained to dry soils; seed germination is significantly increased on decomposed granite as compared to organic matter such as straw (Howard, 1998).

Climate

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ClimateStatusDescriptionRemark
BS - Steppe climate Preferred > 430mm and < 860mm annual precipitation
Cs - Warm temperate climate with dry summer Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers
Cw - Warm temperate climate with dry winter Preferred Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)
Dw - Continental climate with dry winter Preferred Continental climate with dry winter (Warm average temp. > 10°C, coldest month < 0°C, dry winters)

Rainfall

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ParameterLower limitUpper limitDescription
Mean annual rainfall2501000mm; lower/upper limits

Rainfall Regime

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Soil Tolerances

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Soil drainage

  • free

Soil reaction

  • alkaline
  • neutral

Soil texture

  • heavy
  • medium

Notes on Natural Enemies

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The fecundity of B. hordeaceus is reduced by 42–45% when infected by BYDV-SGV (barley yellow dwarf virus) (Seabloom et al., 2009).

Means of Movement and Dispersal

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B. hordeaceus seed is wind dispersed (Frenkel, 1977). 

Pathway Causes

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CauseNotesLong DistanceLocalReferences
Crop production Yes Yes Howard, 1998; Smith, 1968
DisturbanceWeed fields, disturbed areas & waste space Yes HITCHCOCK, 1935
ForageVariety Blando (Reg.No. 11) Yes Yes Alderson and Sharp, 1993; Howard, 1998; Smith, 1968
Habitat restoration and improvement Yes USDA-NRCS, 2005
Intentional release Yes USDA-NRCS, 2005
Landscape improvement Yes USDA-NRCS, 2005
Seed tradeCommon forage grass contaminate Yes Yes Smith, 1968

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Wind Yes Williams et al., 2011

Impact Summary

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CategoryImpact
Economic/livelihood Negative
Environment (generally) Negative

Economic Impact

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B. hordeaceus is a weed of cereal crop fields (Smith, 1968; Cussans et al., 1994; Rowarth et al., 1995; Howard, 1998; Viggiani, 2007), orchards (Elmore, 1989; Lipecki and Janisz, 2000) and turf (Ziron and Opitz von Boberfeld, 2001) and can contaminate grass and clover seed production (Nørtoft, 1985).

Environmental Impact

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B. hordeaceus is an important weed of permanent grasslands (Hopkins and Peel, 1985). B. hordeaceus competes with native vegetation and monopolizes resources (Aanderud et al., 2003).

The California Invasive Plant Council (Cal-IPC) however, classifies the potential impact of B. hordeaceus subsp. hordeaceus on its native ecosystems as limited (Calflora, 2013). 

Threatened Species

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Threatened SpeciesConservation StatusWhere ThreatenedMechanismReferencesNotes
Amaranthus pumilus (seabeach amaranth)NatureServe NatureServe; USA ESA listing as threatened species USA ESA listing as threatened speciesCaliforniaCompetition - monopolizing resourcesUS Fish and Wildlife Service, 2008b
Chorizanthe pungens (Monterey spineflower)NatureServe NatureServe; USA ESA listing as threatened species USA ESA listing as threatened speciesCaliforniaCompetition (unspecified)US Fish and Wildlife Service, 2009b
Pseudobahia bahiifolia (Hartweg's golden sunburst)NatureServe NatureServe; USA ESA listing as endangered species USA ESA listing as endangered speciesCaliforniaCompetition - stranglingUS Fish and Wildlife Service, 2007
Sanicula mariversa (Waianae Range blacksnakeroot)CR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered); USA ESA listing as endangered species USA ESA listing as endangered speciesHawaiiCompetition (unspecified)US Fish and Wildlife Service, 1998; US Fish and Wildlife Service, 2008c
Sidalcea keckii (Keck's checker-mallow)USA ESA listing as endangered species USA ESA listing as endangered speciesCaliforniaCompetition - monopolizing resourcesUS Fish and Wildlife Service, 2008a
Spermolepis hawaiiensis (Hawaii scaleseed)USA ESA listing as endangered species USA ESA listing as endangered speciesHawaiiCompetition - monopolizing resources; Ecosystem change / habitat alterationUS Fish and Wildlife Service, 2010
Speyeria callippe callippe (callippe silverspot butterfly)USA ESA listing as endangered species USA ESA listing as endangered speciesCaliforniaEcosystem change / habitat alterationUS Fish and Wildlife Service, 2009a

Risk and Impact Factors

Top of page Invasiveness
  • Invasive in its native range
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Highly adaptable to different environments
  • Is a habitat generalist
  • 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)
  • Fast growing
  • Has high reproductive potential
  • Has propagules that can remain viable for more than one year
  • Has high genetic variability
Impact outcomes
  • Altered trophic level
  • Changed gene pool/ selective loss of genotypes
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Increases vulnerability to invasions
  • Modification of fire regime
  • Modification of nutrient regime
  • Negatively impacts agriculture
  • Reduced native biodiversity
  • Soil accretion
Impact mechanisms
  • Allelopathic
  • Causes allergic responses
  • Competition - monopolizing resources
  • Competition - strangling
  • Competition
  • Pest and disease transmission
  • Hybridization
  • Rapid growth
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field

Uses

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B. hordeaceus is considered a desirable and nutritious range of forage grass (Laude, 1957; Howard, 1998). It is used for natural or man-made disturbed area erosion control and sediment creation. Examples include bare un-vegetated slopes, such as brush burn areas, newly constructed roads, driveways, housing and industrial developments, gullies, drainages, ditch and channel banks, dikes, levees, dams, reservoirs, and other types of construction on sloping land (USDA-NRCS, 2005).

B. hordeaceus is both an agricultural weed and a control cover crop used in the suppression of other weed species.It is well adapted for reseeding as an annual cover crop on both orchard and vineyard land because it can withstand excessive mowing better than other grasses and matures to seed under minimum watering (USDA-NRCS, 2005).

It is an important food component for both deer and quail (USDA-NRCS, 2005).

Uses List

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Animal feed, fodder, forage

  • Forage

Environmental

  • Agroforestry
  • Erosion control or dune stabilization
  • Land reclamation
  • Landscape improvement
  • Revegetation
  • Soil conservation
  • Soil improvement
  • Wildlife habitat

Human food and beverage

  • Emergency (famine) food

Materials

  • Green manure

Ornamental

  • Seed trade

Detection and Inspection

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B. hordeaceus seed is difficult to detect by mechanical means in pasture grass seed packaging (Smith, 1968). According to Smith (1968) the "incidence of contamination may be a regional or climatic variable depending on methods of cultivation and cleaning and on the amount of effort expended in certifying the seed."

Similarities to Other Species/Conditions

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B. hordeaceus is similar to the Australian native B. arenarius (FloraBase, 2012).

B. hordeaceus can hybridize with B. erectus (Armstrong, 1983) and may intergrade with B. japonicus (Wester, 1981). 

Prevention and Control

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Cultural Control and Sanitary Measures

The use of cover cropping to control B. hordeaceus in place of pesticides has been shown to have a positive effect (Baumgartner et al., 2008).

Fire has little direct effect on B. hordeaceus (Howard, 1998).

Physical/Mechanical Control

Seed set by B. hordeaceus can be prevented by hand pulling (FloraBase, 2012).

Biological Control

B. hordeaceus is infected by Drechslera sp. (perfect stage, Pyrenophora chaetomioides) but not killed (Lawrie et al., 1998).

Chemical Control

B. hordeaceus can be controlled using herbicides. The chemicals pyroxsulam, florasulam and cloquintocet-mexyl have been suggested to provide control of B. hordeaceus (Bucchi et al., 2008). In addition to this, acetic acid has been shown to provide significant control of B. hordeaceus (Young, 2004).

In degraded areas it has been suggested to use 1% glyphosate on seedlings, young plants or when flowering (FloraBase, 2012). Sulfonyl amino carbonyl triazolinone herbicide controls B. hordeaceus in wheat when applied as a post-emergence between the 1 to 2-leaf stage and shoot elongation (Scoggan et al., 1999). Propoxycarbazone-sodium can be applied as a post-emergent in the spring to control B. hordeaceus (Amann, 2002).

Ecosystem Restoration

Removal of litter and duff from natural sites is shown to positively suppress Bromus species (Williams et al., 2011). 

Gaps in Knowledge/Research Needs

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The full relevance of endophytic fungi in B. hordeaceus is not known and merits more research (Williams et al., 2011). Research should be supported by new DNA sequence analyses to resolve species relationships in the genus Bromus (Williams et al., 2011).

Research in potential herbicide resistance should also be supported.

References

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Contributors

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31/05/2013 Original text by:

John Peter Thompson, Consultant, Maryland, USA

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