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Bromus hordeaceus L.

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Family :

Famille :

Poaceae

Synonym(s) :

Synonyme(s) :

The species Bromus hordeaceus L. is comprised of five subspecies; these include B. hordeaceus L. subsp. hordeaceus, B. h. subsp. divarictus (Bonnier & Layens) Kerguélen, B. h. subsp. ferronii (Mabille) P. M. Sm. , B. h. subsp. pseudothominii (P. M. Sm.) Scholz, and B. h. subsp. thominei (Hardouin) Braun-Blanq. (Howard 1998; Barkworth et al. 2007; USDA-ARS-NPGS 2023; USDA-NRCS 2023).

Synonyms for B. hordeaceus L. subsp. hordeaceus:
Bromus hordeaceus L. var. hordeaceus (USDA-ARS-NPGS 2023)
Bromus mollis L. (Tutin et al. 1980; USDA-ARS-NPGS 2023)
Bromus mollis L. var. glabratus Hartm. (USDA-ARS-NPGS 2023)
Bromus mollis L. var. mollis (USDA-ARS-NPGS 2023)

Synonyms for B. hordeaceus L. subsp. divaricatus (Bonnier & Layens) Kerguélen:
Bromus hordeaceus L. subsp. molliformis (J. Lloyd ex Billot) Maire & Weiller (Barkworth et al. 2007; USDA-ARS-NPGS 2023; USDA-NRCS 2023)
Bromus molliformis Lloyd (Tutin et al. 1980; USDA-NRCS 2023)

Synonyms for B. hordeaceus L. subsp. ferronii (Mabille) P. M. Sm.
Bromus ferronii Mabille (Tutin et al. 1980; USDA-ARS-NPGS 2023; USDA-NRCS 2023)

Synonyms for B. hordeaceus L. ssp. pseudothominii (P.M. Sm.) H. Scholz
Bromus mollis L. var. leiostachys Hartm. (USDA-NRCS 2023)
Bromus pseudothominii P.M. Sm. (pro hybr.) (USDA-NRCS 2023)
Bromus × pseudothominii P.M. Sm. (Tutin et al. 1980)

Synonyms for B. hordeaceus L. subsp. thominei (Hardouin) Braun-Blanq.
Bromus mollis L. var. thominei (Hardouin) Bréb. (USDA-ARS-NPGS 2023)
Bromus thominei Hardouin (Tutin et al. 1980; USDA-ARS-NPGS 2023; USDA-NRCS 2023)

Common Name(s) :

Nom(s) commun(s) :

Soft chess

(English) (Wiersema and León 1999; AOSA 2023b; CABI 2023; USDA-ARS-NPGS 2023)
Blando brome (English) (AOSA 2023b)
Soft brome (English) (Wiersema and León 1999; CABI 2023; USDA-NRCS 2023)
Common soft brome (English) (CABI 2023; USDA-ARS-NPGS 2023)
Lopgrass (English) (Pavlick 1995; Wiersema and León 1999; Barkworth et al. 2007)
Bromo blando (Spanish) (CABI 2023)
Bromo suelto (Spanish) (CABI 2023)
Brome fausse orge (French) (CABI 2023)
Brome mou (French) (Barkworth et al. 2007; CABI 2023)
Mao que mai (毛雀麦Chinese) (eFloras 2023)

Soft chess (Bromus hordeaceus) florets

  • Soft chess (Bromus hordeaceus) florets

  • Soft chess (Bromus hordeaceus) florets

  • Soft chess (Bromus hordeaceus) florets

  • Soft chess (Bromus hordeaceus) floret, palea teeth

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Overview

Aperçu

Regulation :

Remarques Réglementation:

    Regulation Notes:

    Distribution :

    Répartition :

    Bromus hordeaceus is native to Eurasia, where it is most commonly found in the Mediterranean region (Howard 1998). It is native to Europe, parts of temperate and tropical Asia and northern Africa (USDA-ARS-NPGS 2023). The species has been introduced and naturalized in regions of all continents except Antarctica (Howard 1998).

    Habitat and Crop Association :

    Habitat et Cultures Associées :

    Bromus hordeaceus is commonly found in crop fields (Festuca pratensis, Lolium perenne, Secale cereale, Triticum aestivum), meadows, sagebrush communities, rangeland, disturbed sites, orchards (Prunus dulcis, P. persica), and vineyards (DiTomaso et al. 2013; CABI 2023).

    Where introduced, B. hordeaceus can become a weedy pest competing with native vegetation and monopolizing resources (CABI 2023). For example, B. hordeaceus has become naturalized in the grassland communities of California and Oregon replacing native perennial grasses and annual forbs (Howard 1998).

    Economic Use, cultivation area, and Weed Association :

    Utilisation économique, zone de culture et association de mauvaises herbes :

    Bromus hordeaceus is sold commercially and used as a forage crop, for erosion control, and as a cover crop in orchards and vineyards (Alderson and Sharp 1995; Dyer and O’Beck 2005). It is a nutritious and highly palatable forage, and due to its short and soft awns the seeds can also be consumed allowing grazing to occur even after seeds mature (Howard 1998).

    Duration of Life Cycle :

    Durée du cycle vital:

    Annual or biennial

    Dispersal Unit Type :

    Type d’unité de dispersion :

    Floret

    General Information

    RENSEIGNEMENTS GÉNÉRAUX

    Bromus hordeaceus is a cool-season annual or biennial grass that reproduces by seed and is self-pollinating (Pavlick 1995; Howard 1998).  Seed dispersal can be achieved through soil movement, wildlife and human activities, and as a contaminant of commercial seed lots (DiTomaso et al. 2013). There was little or no seed dormancy observed in B. hordeaceus with the seed bank being most viable during the first year (CABI 2022), and very few seeds carry over from year to year in the seedbank (Howard 1998). B. hordeaceus seeds require light and may require stratification for germination under laboratory conditions (AOSA 2023a).

    The species Bromus hordeaceus L. is comprised of five subspecies. Diagnostic features include:

    B. hordeaceus L. subsp. hordeaceus, soft chess (USDA-ARS-NPGS 2023)
    Lemmas (7)8 – 11 mm long, margins bluntly angled, surface usually hairy; awn 4 – 11 mm long, straight, erect, base greater than 0.1 mm wide and round in cross-section; caryopsis shorter than palea (Tutin et al. 1980; Barkworth et al. 2007). Native to Europe, northern Africa, and temperate Asia, introduced into the Americas, Eurasia, South Africa, Australasia, and some Pacific islands (CABI 2023).

    B. hordeaceus L. subsp. divaricatus (Bonnier & Layens) Kerguélen
    Lemmas (7)8 – 11 mm long, margins rounded, surface hairy; awn 6 – 10 mm long, curved at maturity, often twisted, awn base less than 0.1 mm wide and flattened in cross-section; caryopsis shorter than palea (Tutin et al. 1980; Barkworth et al. 2007). Native to northern Africa, Spain, Portugal, Cyprus, Turkey, southern Europe, and is found in few scattered locations in the United States (Barkworth et al. 2007; USDA-NRCS 2023)

    B. hordeaceus L. subsp. ferronii (Mabille) P. M. Sm., least soft brome (USDA-ARS-NPGS 2023)
    Lemmas 6.5 – 8.5 mm long, margins bluntly angled, surface densely hairy; awn 2 – 2.5 mm long, curved at maturity, awn base flattened in cross-section (Tutin et al. 1980). Native to cliff tops in northwestern Europe (Tutin et al. 1980).

    B. hordeaceus L. ssp. pseudothominii (P.M. Sm.) H. Scholz
    Lemmas 6.5 – 8(9) mm long, margins abruptly angled, surface usually glabrous; awn straight; caryopsis usually as long as palea (Tutin et al. 1980; Pavlick 1995; Barkworth et al. 2007). Found sporadically in the range of the species (Pavlick 1995; Barkworth et al. 2007)

    B. hordeaceus L. subsp. thominei (Hardouin) Braun-Blanq., sand soft brome (USDA-ARS-NPGS 2023).
    Inflorescence often reduced to one spikelet; lemmas 6.5 – 7.5 mm long, margins bluntly angled, surface hairy or not; awns 3 – 7 mm long, slender, awn base round in cross-section, straight or slightly curved at maturity; caryopsis shorter than palea (Tutin et al. 1980; Barkworth et al. 2007). Native to coastal areas of western Europe (Tutin et al. 1980), found along the Pacific coast of Canada to Oregon, inland areas of British Columbia, and northeastern coastal areas in the United States (Pavlick 1995; Barkworth et al. 2007).

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    Identification

    Identification

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    • Spikelet

      Size

      • Spikelet length: (11) 14 – 20 (23) mm (Barkworth et al. 2007); width 2 – 6 mm (Tutin et al. 1980).
      • Lower (1st) glume length: 5 – 7 mm; upper (2nd) glume length: 6.5 – 8 mm (Barkworth et al. 2007).

      Shape

      • Spikelets narrowly teardrop shaped (lanceolate), round to slightly compressed laterally (Barkworth et al. 2007).

      Surface Texture

      • Glumes thin and papery.
      • Surface may or may not be covered with soft hairs.
      • Lower (1st) glume 3 – 5 nerved; upper (2nd) glume 5 – 7 nerved (Barkworth et al. 2007).

      Colour

      • Spikelet colour light brownish yellow.

      Other Features

      • Spikelet composed of 5 – 10 similar looking florets (Barkworth et al. 2007).
      • Florets furthest away from spikelet base (distal florets) are usually sterile and slightly smaller in size.
      • Disarticulation of the spikelet occurs above glumes and between florets at the rachilla nodes.

    • Floret

      Size

      • Floret length*: 6.7 – 9.5 mm (average 8.2 mm); width*: 1.2 – 2.5 mm (average 1.8 mm).
      • Lemma teeth length*: 0.5 – 1.5 mm.
      • Rachilla length*: 0.7 – 1.8 mm (average 1.0 mm)
      • Awn length*: 2.3 – 7.7 mm (average 5.6 mm); awn attached less than 1.5 mm below lemma tip.
      • Palea shorter than lemma, but equal to or longer than caryopsis.
      *Note: minimum and maximum based on a random selection of 30 florets in normal range of this species using image measurement protocol (ISMA 2020). CDA-S-22205. CDA-S-22277, CDA-S-26221.

      Floret size measurements from the literature:
      • Lemma length 7 – 8 mm (Pavlick 1995).
      • Floret length 8 – 11 mm, width 2 mm in lateral view; awn 5 – 10 mm long. (eFloras 2023).
      • Lemma length 7.7 – 8.3 mm, width 1.8 – 2 mm; awn up to 10 mm long (Bojňanský and Fargašová 2007).
      • Lemma length 6.5 – 11 mm, width 3 – 5 mm; awn 6 – 8 mm long (Barkworth et al. 2007).

      Shape

      • Floret oval to egg-shaped; dorsoventrally compressed.
      • Lemma margins usually slightly in rolled in lower two-thirds and flared out in upper one-third.
      • Lemma back rounded, apex split into two teeth (bifid).
      • Awn straight or slightly curved, base round or flattened.
      • Rachilla round in cross-section and flattened at apex, detachment (disarticulation) scar nearly circular.
      • Callus short, blunt, and smooth, attachment point nearly circular.

      Surface Texture

      • Lemma texture papery, usually transversely wrinkled.
      • Lemma surface usually covered with soft hairs, especially in upper half, or without hairs.
      • Lemma 5 – 7 nerved, nerves may or may not be visible.
      • Palea membranous and transparent, usually hairy between keels.
      • Palea keel hairs (palea teeth) long and widely spaced.
      • Rachilla covered with short stiff hairs.

      Colour

      • Floret pale brownish yellow coloured.

      Soft chess (Bromus hordeaceus) florets

    • Caryopsis

      Size

      • Caryopsis length* 5.1 – 6.5 mm (average 5.8 mm); width* 1.4 – 1.8 mm (average 1.7 mm).
      *Note: Minimum and maximum based on a random selection of 10 caryopses in normal range of this species using image measurement protocol (ISMA 2020). CDA-S-22276.

      Caryopsis measurements from the literature:
      • Caryopsis length 6 – 7 mm, width 1.7 – 1.9 mm (Bojňanský and Fargašová 2007).

      Shape

      • Caryopsis spindle shaped (fusiform) to inverse teardrop shaped (oblanceolate), dorsoventrally flattened to slightly U-shaped in cross-section.

      Surface Texture

      • Surface of the caryopsis smooth, lemma and palea may be adherent.

      Colour

      • Caryopsis colour light reddish-brown.

      Other Features

      • Hilum linear, extending nearly the full length of the caryopsis.
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    <
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    • Embryo

      Size

      • Embryo length*: 0.7 – 1.2 mm (average 1.1 mm).
      • Embryo about one-eighth the length of the caryopsis.
      *Note: minimum and maximum based on a random selection of 10 embryos in normal range of this species using image measurement protocol (ISMA 2020). CDA-S- 22276.

      Shape

      • Embryo diamond or teardrop shaped

      Endosperm

      • Endosperm solid (Terrell 1971).

      Other Features

      • Embryo in lateral position (Martin 1946).
      • Embryo with slender root-shoot axis, scutellum outline visible.

    Identification Tips

    CONSEILS POUR L’IDENTIFICATION

    The florets of Bromus hordeaceus are similar to other species of Bromus that have thin caryopses and long palea keel hairs (palea teeth) as found in B. arvensis, B. commutatus, and B. japonicus.

    Bromus hordeaceus florets are generally more delicate looking than those of the similar species and diagnostic features are described as follows:

    • Floret may be slightly inrolled, or the base may be inrolled and the upper half flared out nearly flat.
    • Lemma tends to be very thin and pliable like tissue paper, wrinkled and usually covered with soft hairs, and the nerves are usually prominent.
    • Palea is membranous, transparent, and shorter than the lemma.
    • Awn is straight or curved and attached less than 1.5 mm from the lemma tip.
    • Caryopsis is thin, weakly inrolled or flat, and is equal to or shorter than the palea.

    Note: lemma hairs, awns and portions of the lemma may be milled off during conditioning of commercial seed lots of B. hordeaceus or that may be contaminated with B. hordeaceus or similar species making positive identification difficult.

    Soft chess (Bromus hordeaceus) florets

    Additional Botany Information

    AUTRES RENSEIGNEMENTS BOTANIQUES

    Flowers/Inflorescence

    • The inflorescence is an upright, dense, contracted panicle, 1 – 13 cm long and 1 – 4 cm wide, the branches are shorter than the spikelets (Barkworth et al. 2007; DiTomaso and Healy 2007).

    Vegetative Features

    • Stem up to 70 cm tall.
    • Roots fibrous and mostly located in the top 15 cm of soil.
    • Lower leaf sheaths covered with long soft hairs, upper sheaths hairy or smooth.
    • Leaf blades 2 – 19 cm long, 1 – 10 mm wide, soft hairy on upper surface or on both sides.

    Description based on Barkworth et al. (2007) and DiTomaso and Healy (2007).

    Similar Species

    ESPÈCES SEMBLABLES

    Similar species are based on a study of seed morphology of various species, and those with similar dispersal units are identified. The study is limited by physical specimen and literature availability at the time of examination, and possibly impacted by the subjectivity of the authors based on their knowledge and experience. Providing similar species information for seed identification is to make users aware of similarities that could possibly result in misidentification.

    The genus Bromus is divided into five sections, of which Bromus hordeaceus and similar species B. arvensis, B. commutatus, and B. japonicus belong to Section Bromus (Barkworth et al. 2007) or Subgenus Bromus (USDA-ARS-NPGS 2023). Floret length and the length of the lemma teeth (1 mm) in these four species are about the same.

    Bromus arvensis (field brome) – The florets of B. arvensis are a similar size (length**: 5.5 – 7.8 mm; width**: 1.3 – 2.0 mm) as B. hordeaceus, but tend to be inrolled giving a narrow appearance in palea view and in lateral view the floret is widest about one-third the length from the tip; the lemma and palea are similar in length; the lemma is usually not hairy or may have short stiff hairs in the upper half and the nerves are obscure, while in B. hordeaceus the lemma is usually covered with soft hairs and the nerves are prominent; the awn is straight, attached at varying distances below the lemma tip, and is longer (6 – 11 mm long; Barkworth et al. 2007) than in B. hordeaceus; the caryopsis is shorter than the palea and is weakly to strongly inrolled, while in B. hordeaceus the caryopsis is usually flattened.

    Bromus commutatus (hairy chess) – The florets of B. commutatus are a similar size (length: 8 – 11 mm; Barkworth et al. 2007) as B. hordeaceus, but tend to be inrolled and only slightly flared near the tip, in lateral view the floret is widest slightly above the middle; the lemma is usually smooth, the lateral nerves are obscure, and the surface is hairless or may be hairy near the margins, while in B. hordeaceus the lemma is wrinkled, the nerves prominent, and the surface is usually covered with soft hairs; the awn is straight, attached less than 1.5 mm below tip of the lemma, and is slightly longer (3 – 10 mm long; Barkworth et al. 2007) than in B. hordeaceus; the caryopsis is equal to or shorter than the palea, and weakly to strongly inrolled, while in B. hordeaceus the caryopsis is usually flattened.

    Bromus japonicus (Japanese brome) – The florets of B. japonicus are a similar size (length**: 7.1 – 9.2 mm; width**: 1.3 – 1.7 mm) as B. hordeaceus, but tend to be inrolled and in lateral view the floret is widest slightly above the middle; the lemma is smooth or minutely short hairy in upper half and the lateral nerves are usually obscure; the palea is markedly shorter than the lemma; the awn is much longer (8 – 13 mm long; Barkworth et al. 2007) than in B. hordeaceus, is attached 1.5 mm or more below the tip of the lemma, and is curved away from the lemma; the caryopsis is equal to or shorter than the palea, thin, weakly inrolled or flat (Barkworth et al. 2007). B. japonicus is a regulated weed seed in the state of Wyoming when found as a seed lot contaminant in excess of 1,200 seeds per pound (USDA-AMS 2023).

    ** Note: minimum and maximum of 10 florets in a normal range of this species using image measurement (ISMA 2020), measurements by CFIA.

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    Reference(s)

    Référence(s)

    Alderson, J. and Sharp, W. C.  1995. Grass varieties in the United States, USDA Agric. Handbook 170, rev. ed. CRC Press.

    Association of Official Seed Analysts (AOSA). 2023a. Rules for Testing Seeds, Vol. 1: Principles and Procedures. Association of Official Seed Analysts, Wichita, KS, USA.

    Association of Official Seed Analysts (AOSA). 2023b. Rules for Testing Seeds, Vol. 3: Uniform Classification of Weed and Crop Seeds. Association of Official Seed Analysts, Wichita, KS, USA.

    Barkworth, M. E., Capels, K. M., Long, S. and Piep, M. B. (eds.). 2007. Flora of North America Volume 24. Magnoliophyta: Commelinidae (in part): Poaceae, part 1. Oxford University Press, New York, New York.

    Bojňanský, V. and Fargašová, A. 2007. Atlas of Seeds and Fruits of Central and East-European Flora: The Carpathian Mountains Region. Springer, Dordrecht, The Netherlands.

    Center for Agriculture and Bioscience International (CABI). 2023. Bromus hordeaceus (soft brome) – Datasheet. Invasive Species Compendium. https://www.cabi.org/isc/datasheet/10026.  Accessed: November 17, 2023.

    DiTomaso, J. M. and Healy, E. A. 2007. Weeds of California and Other Western States. Vol. 2: Geraniaceae – Zygophyllaceae. Agriculture and Natural Resources Publication 3488. University of California, Oakland, CA.

    DiTomaso, J. M., Kyser, G. B. et al. 2013. Soft Brome (Soft Chess) and Japanese Brome. Weed Control in Natural Areas in the Western United States. Weed Research and Information Center, University of California. pp. 544. https://wric.ucdavis.edu/information/natural%20areas/wr_B/Bromus_hordeaceus-japonicus.pdf.

    Dyer, D. and O’Beck, R. 2005. Soft Chess, Bromus hordeaceus L. ssp. hordeaceus Plant Guide. United States Department of Agriculture – Natural Resources Conservation Service. https://plants.usda.gov/DocumentLibrary/plantguide/pdf/pg_brhoh.pdf

    eFloras. 2023. Flora of China. www.efloras.org.  Accessed November 17, 2023.

    Howard, J. L. 1998. Bromus hordeaceus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service,  Rocky Mountain Research Station, Fire Sciences Laboratory (Producer).   https://www.fs.usda.gov/database/feis/plants/graminoid/brohor/all.html  Accessed November 14, 2023.

    International Seed Morphology Association (ISMA). 2020. Method for seed size measurement. Version 1.0. ISMA Publication Guide. https://www.idseed.org/authors/details/method_for_seed_size_measurement.html.

    Martin, A. C. 1946. The comparative internal morphology of seeds. The American Midland Naturalist 36(3):513-660.

    Pavlick, L. E. 1995. Bromus L. of North America. Royal British Columbia Museum.

    Terrell, E. E. 1971. Survey of occurrences of liquid or soft endosperm in grass genera. Bull. Torr. Botan. Club 98(5):264-268.

    Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Waters, S. M., Webb, D. A. (Eds.). 1980. Flora Europaea. Volume 5: Alismataceae to Orchidaceae (Monocotyledons). Cambridge University Press.

    United States Department of Agriculture-Agricultural Marketing Service (USDA-AMS). 2023. State Noxious-Weed Seed Requirements Recognized in the Administration of the Federal Seed Act. https://www.ams.usda.gov/sites/default/files/media/StateNoxiousWeedsSeedList.pdf  Accessed November 17, 2023.

    United States Department of Agriculture-Agricultural Research Service-National Plant Germplasm System (USDA-ARS-NPGS). 2023. National Plant Germplasm System. Germplasm Resources Information Network (GRIN Taxonomy). National Germplasm Resources Laboratory, Beltsville, Maryland. http://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomydetail?id=7320.  Accessed November 17, 2023.

    United States Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS). 2023. The PLANTS Database. National Plant Data Team, Greensboro, NC USA. http://plants.usda.gov  Accessed February 15, 2023.

    Wiersema, J. H. and León, B. 1999. World economic plants: a standard reference. CRC Press, Boca Raton, FL.

    Author(s)

    AUTEUR(S)

    Deborah J. Lionakis Meyer, California Department of Food and Agriculture (retired)

    Acknowledgements

    The author wishes to thank the following from the Canadian Food Inspection Agency (CFIA): reviewers Jennifer Neudorf and Angela Salzl for their suggestions for fact sheet improvement and Krishan Shah, former student, for his assistance with literature search and summary.

    contactus@idseed.org

    Last updated
    on 2023-03-27

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