Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide


Bromus hordeaceus
(soft brome)



Bromus hordeaceus (soft brome)


  • 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...

Don't need the entire report?

Generate a print friendly version containing only the sections you need.

Generate report


Top of page
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
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


Top of page

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

Top of page

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

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

Notes on Taxonomy and Nomenclature

Top of page

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.


Top of page

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).


Top of page

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

Top 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/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes


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


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
-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


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


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


Top of page

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

Top of page
Terrestrial – ManagedCultivated / agricultural land Principal habitat
Managed forests, plantations and orchards Principal habitat
Managed grasslands (grazing systems) Principal habitat
Industrial / intensive livestock production systems Principal habitat
Disturbed areas Principal habitat
Rail / roadsides Principal habitat
Urban / peri-urban areas Secondary/tolerated habitat
Terrestrial ‑ Natural / Semi-naturalNatural 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
Deserts Present, no further details
Arid regions Present, no further details
Coastal areas Present, no further details
Coastal dunes Secondary/tolerated habitat

Growth Stages

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

Biology and Ecology

Top of page


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).


Top of page
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)


Top of page
ParameterLower limitUpper limitDescription
Mean annual rainfall2501000mm; lower/upper limits

Notes on Natural Enemies

Top of page

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

Top of page

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

Impact Summary

Top of page
Economic/livelihood Negative
Environment (generally) Negative

Economic Impact

Top of page

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

Top of page

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

Top of page
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


Top of page

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).

Detection and Inspection

Top of page

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

Top of page

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

Top 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.

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

Top of page

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.


Top of page

Aanderud ZT, Bledsoe CS, Richards JH, 2003. Contribution of relative growth rate to root foraging by annual and perennial grasses from California oak woodlands. Oecologia, 136(3):424-430.

Acedo C, Llamas F, 1999. The genus Bromus L. (Poaceae) in the Iberian Peninsula. Phanerogamarum Monographiae XXII. Stuttgart, Germany: J Cramer in der Gebruder Bornträger Verlagsbuchhandlung.

Ainouche ML, Bayer RJ, Gourret JP, Defontaine A, Misset MT, 1999. The allotetraploid invasive weed Bromus hordeaceus L. (Poaceae): genetic diversity, origin and molecular evolution. Folia Geobotanica, 34(4):405-419.

Alderson J, Sharp WC, 1993. Grass Varieties in the United States. Agriculture Handbook No. 170 revised edition. Washington, DC, USA: United States Department of Agriculture.

Amann A, 2002. Propoxycarbazone-sodium - the chemical cornerstone of integrated brome-grass management in Germany. Pflanzenschutz-Nachrichten Bayer, 55(1):87-100.

Armstrong KC, 1983. The relationship between some Eurasian and American species of Bromus section Pnigma as determined by the karyotypes of some F1 hybrids. Canadian Journal of Botany, 61(3):700-707.

Barkworth ME, Capels KM, Long S, Anderton LK, Piep MB, 2007. Grass manual on the Web. Flora of North America, Vol. 24. Logan, Utah, USA: Utah State University.

Baumgartner K, Steenwerth KL, Veilleux L, 2008. Cover-crop systems affect weed communities in a California vineyard. Weed Science, 56(4):596-605.

Brouillet L, Coursol F, Favreau M, 2006. VASCAN. The database of Canadian vascular plants. Montreal, Canada: Herbier Marie-Victorin, Institut de Recherche en Biologie Vegetale.

Bucchi R, Campagna G, Rapparini G, 2008. Efficacy of new post-emergence herbicides against Bromus mollis in wheat. (Verifica dell'attività di nuovi erbicidi di post-emergenza del frumento su Bromus mollis.) In: Giornate Fitopatologiche 2008, Cervia (RA), 12-14 marzo 2008, Volume 1 [ed. by Brunelli, A.]. Bologna, Italy: Università di Bologna, 407-412.

Calflora, 2013. Calflora: Information on wild California plants for conservation, education, and appreciation.

Clarke J, Moss S, Orson J, 2000. The future for grass weed management in the UK. Pesticide Outlook, 11(2):59-63.

Cussans GW, Cooper FB, Davies DHK, Thomas MR, 1994. A survey of the incidence of the Bromus species as weeds of winter cereals in England, Wales and parts of Scotland. Weed Research (Oxford), 34(5):361-368.

Dastgheib F, Poole N, 2010. Seed biology of brome grass weeds (Bromus diandrus and B. hordeaceus) and effects of land management. New Zealand Plant Protection 63:78-83.

Ellis RH, Hong TD, Roberts EH, 1986. The response of seeds of Bromus sterilis L. and Bromus mollis L. to white light of varying photon flux density and photoperiod. New Phytologist, 104(3):485-496.

Elmore CL, 1989. Vegetation management systems in almond orchards. California Agriculture, 43(4):16-17.

eMonocot, 2013. eMonocot: An online resource for monocot plants.

Euro+Med, 2013. Euro+Med PlantBase.

Ewing AL, Menke JW, 1983. Response of soft chess (Bromus mollis) and slender oat (Avena barbata) to simulated drought cycles. Journal of Range Management, 36(4):415-418.

FAO, 2012. Grassland Species Profiles. Grassland Species Profiles. Rome, Italy: FAO.

Flora of China Editorial Committee, 2006. Flora of China. Flora of China, 22. 213-216.

FloraBase, 2012. The Western Australian Flora. Western Australia, Australia: Department of Environment and Conservation.

Frenkel RE, 1977. Ruderal Vegetation Along Some California Roadsides. Berkeley, CA, USA: University of California Press.

GBIF, 2012. Global Biodiversity Information Facility. Global Biodiversity Information Facility (GBIF).

Geological Survey US, 2013. Biodiveristy information serving our nation - US species occurrance data and maps., USA.

Gibbs Russell GE, Welman WG, Reitief E, Immelman KL, Germishuizen G, Pienaar BJ, Wyk Mvan, Nicholas A, 1987. List of species of southern African plants. Memoirs of the Botanical Survey of South Africa, 2(1 & 2):1-152 & 1-270.

Grass Phylogeny Working Group, 2001. Phylogeny and subfamilial classification of the grasses (Poaceae). Annals of the Missouri Botanical Garden, 88(3):373-457.

Hamal A, Benbella M, Rzozi SB, Bouhache M, Msatef Y, 2001. Cartography and geographical spread of the weedy bromes (Bromus spp.) of cereals in the Sais area of Morocco. Mededelingen - Faculteit Landbouwkundige en Toegepaste Biologische Wetenschappen, Universiteit Gent, 66(2b):761-768.

Hitchcock AS, 1935. Manual of the grasses of the United States. Washington, DC, USA: Superintendent of Documents, 1040 pp.

Hopkins A, Peel S, 1985. Incidence of weeds in permanent grassland. In: Weeds, pests and diseases of grasslands and herbage legumes [ed. by Brockman, J.S.]. Croydon, UK: British Crop Protection Council, 93-103.

Howard JL, 1998. Bromus hordeaceus. Fire Effects Information System., USA: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

ITIS, 2013. Integrated Taxonomic Information System (ITIS). Washington, DC, USA: Smithsonian Institution/NMNH.

Jensen PK, 2009. Longevity of seeds of four annual grass and two dicotyledon weed species as related to placement in the soil and straw disposal technique. Weed Research (Oxford), 49(6):592-601.

Larigauderie A, Hilbert DW, Oechel WC, 1988. Effect of CO2 enrichment and nitrogen availability on resource acquisition and resource allocation in a grass, Bromus mollis. Oecologia, 77(4):544-549.

Laude HM, 1957. Comparative pre-emergence heat tolerance of some seeded grasses and of weeds. Botanical Gazette, 119(1):44-46.

Lawrie J, Greaves MP, Down VM, 1998. Drechslera sp. (Pyrenophora chaetomioides (Speg.)), a potential biocontrol agent for Bromus sterilis and other Bromus spp. Biocontrol Science and Technology, 8(4):479-484.

Lipecki J, Janisz A, 2000. Spatial distribution and changes in occurrence of some weed species in the orchard in AES Felin near Lublin. (Rozmieszczenie przestrzenne oraz zmiany w wystepowaniu niektórych gatunków chwastów w sadzie jaboniowym Gospodarstwa Doswiadczalnego Felin koo Lublina.) Acta Agrobotanica, 53(2):85-104.

Lönn M, 1993. Genetic structure and allozyme-microhabitat associations in Bromus hordeaceus. Oikos, 68(1):99-106.

Lövkvist B, Hultgard U-M, 1999. Chromosome numbers in south Swedish vascular plants, 137. Sweden: Council for Nordic Publications in Botany, 42 pp.

Millspaugh CF, Nuttall LW, 1896. Flora of West Virginia. Chicago, USA: Field Columbian Museum, 276.

MingJer J, GwoIng L, ChangSheng K, 2006. Notes on alien Bromus grasses in Taiwan. Taiwania, 51(2):131-138.

Nørtoft B, 1985. Problems with weed seed contamination in herbage seed. Dansk Frøavl, 68(6):134-136.

PIER, 2012. Pacific Islands Ecosystems at Risk. Honolulu, USA: HEAR, University of Hawaii.

Planchuelo AM, Peterson PM, 2000. The species of Bromus (Poaceae: Bromae) in South America. In: Grasses: Systematics and Evolution [ed. by Jacobs, S. W. L. \Everett, J.]. Collingwood, Victoria, Australia: CSIRO Publishing, 89-101.

Prieto-Baena JC, Hidalgo PJ, Domínguez E, Galán C, 2003. Pollen production in the Poaceae family. Grana, 42(3):153-160.

Pyšek P, Sadlo J, Mandak B, 2002. Catalogue of Alien Plants of the Czech Republic. Preslia, Praha, 74:97-186.

Randall RP, 2012. A Global Compendium of Weeds. Perth, Australia: Department of Agriculture and Food Western Australia, 1124 pp.

Rowarth JS, Johnson AA, Rolston MP, Clifford PTP, 1995. Weed seeds in white clover and ryegrass seedlots: an aspect of seed quality. In: Proceedings Annual Conference - Agronomy Society of New Zealand, 25. 55-58.

Scholz H, 2008. Some comments on the genus Bromus (Poaceae) and three new species. Willdenowia, 38(2):411-422.

Scoggan AC, Santel HJ, Wollam JW, Rudolph RD, 1999. BAY MKH 6561: a new herbicide for grass and broadleaf weed control in cereals. 1999 Brighton crop protection conference: weeds. Proceedings of an international conference, Brighton, UK, 15-18 November 1999., Volume 1:93-98.

Seabloom EW, Borer ET, Jolles A, Mitchell CE, 2009. Direct and indirect effects of viral pathogens and the environment on invasive grass fecundity in Pacific Coast grasslands. Journal of Ecology (Oxford), 97(6):1264-1273.

Shock CC, Williams WA, Jones MB, Center DM, Phillips DA, 1984. Nitrogen fixation by subclover associations fertilized with sulfur. Plant and Soil, 81(3):323-332.

Smith PM, 1968. The Bromus mollis aggregate in Britain. Watsonia, 6:327-344.

Smith PM, 1983. Proteins, mimicry and microevolution in grasses. In: Proteins and nucleic acids in plant systematic [ed. by Jensen, U. \Fairbrothers, D. E.]., Germany: Springer-Verlag Berlin and Heidelberg, 311-323.

Solymosi P, 1989. Studies of the occurrence of Bromus species in Pest County. Novenyvedelem, 25(5):193-198

Stapanian MA, Sundberg SD, Baumgardner GA, Liston A, 1998. Alien plant species composition and associations with anthropogenic disturbance in North American forests. Plant Ecology, 139(1):49-62.

Tropicos, 2012. Tropicos. Missouri, USA: Missouri Botanical Garden.

US Fish and Wildlife Service, 1998. In: Recovery Plan for Oahu Plants. US Fish and Wildlife Service, 207 pp. + appendices.

US Fish and Wildlife Service, 2007. In: Pseudobahia bahiifolia (Hartweg's golden sunburst), Pseudobahia peirsonii (San Joaquin adobe sunburst). 5-Year Review: Summary and Evaluation. US Fish and Wildlife Service, 23 pp..

US Fish and Wildlife Service, 2008. In: Keck's Checkermallow (Sidalcea keckii). 5-Year Review: Summary and Evaluation. US Fish and Wildlife Service, 13 pp..

US Fish and Wildlife Service, 2008. In: Purple Amole (Chlorogalum purpureum). Five-year Review: Summary and Evaluation. US Fish and Wildlife Service, 33 pp..

US Fish and Wildlife Service, 2008. In: Sanicula mariversa (no common name). 5-Year Review: Summary and Evaluation. US Fish and Wildlife Service, 10 pp..

US Fish and Wildlife Service, 2009. In: Callippe Silverspot Butterfly (Speyeria callippe callippe). 5-Year Review: Summary and Evaluation. US Fish and Wildlife Service, 29 pp..

US Fish and Wildlife Service, 2009. In: Monterey Spineflower (Chorizanthe pungens var. pungens). 5-Year Review: Summary and Evaluation. US Fish and Wildlife Service, 21 pp..

US Fish and Wildlife Service, 2010. In: Spermolepis hawaiiensis (no common name). 5-Year Review: Summary and Evaluation. US Fish and Wildlife Service, 19 pp..

USDA-ARS, 2013. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory.

USDA-NRCS, 2005. Soft Chess - Bromus hordeaceus L. ssp. hordeaceus. California, USA.

USDA-NRCS, 2013. Plants Database. USA: United States Department of Agriculture-Natural Resources Conservation Office.

Viggiani P, 2007. Identification of weedy bromes (Bromus spp. L.) and their distribution in wheat fields in Italy. (Identificazione dei Forasacchi (Bromus spp. L.) e loro distribuzione nelle colture di frumento in Italia.) Informatore Fitopatologico, 57(3):19-24.

Völler E, Auge H, Bossdorf O, Prati D, 2013. Land use causes genetic differentiation of life-history traits in Bromus hordeaceus. Global Change Biology, 19(3):892-899.

Watson L, Dallwitz MJ, 1992. The Families of Flowering Plants: Descriptions, Illustrations, Identification and Information Retrieval. Version: 19th August 1999.

Wester L, 1981. Composition of native grasslands in the San Joaquin Valley, California. Madrono, 28(4):231-241.

Williams WM, Stewart AV, Williamson ML, 2011. Bromus. In: Wild crop relatives: genomic and breeding resources: millets and grasses, 2 [ed. by Kole, C.]. 15-30.

Wittig R, Xie YingZhong, Raus T, Scholz H, 2000. Addenda ad floram Ningxiaensem - supplement to the flora of the Autonomous Region Ningxia, China. Willdenowia, 30(1):105-113.

Young SL, 2004. Natural product herbicides for control of annual vegetation along roadsides. Weed Technology, 18(3):580-587.

Ziron C, Opitz von Boberfeld W, 2001. The germination behaviour of widespread turf weeds and grasses. (Zum Keimverhalten verbreiteter Rasenunkräuter und -gräser.) Rasen-Turf-Gazon, 32(2):37-42.


Top of page

31/05/2013 Original text by:

John Peter Thompson, Consultant, Maryland, USA

Distribution Maps

Top of page
You can pan and zoom the map
Save map