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Bromus sterilis L.

Overview
General Information
ID Info
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Family :

Famille :

Poaceae

Synonym(s) :

Synonyme(s) :

Anisantha sterilis (L.) Nevski (USDA-ARS-NPGS 2023)
Genea sterilis (L.) Dumort. (CABI 2023)

Common Name(s) :

Nom(s) commun(s) :

Barren chess

(English) (AOSA 2023)
Barren brome (English) (Wiersema and León 1999; DiTomaso & Healy 2007; CABI 2023)
Barren bromegrass (English) (CABI 2023)
Poverty brome (English) (Terrell et al. 1986; DiTomaso & Healy 2007; CABI 2023; USDA-NRCS 2023)
Sterile brome (English) (Terrell et al. 1986; CABI 2023)
Bromo esteril (Spanish) (CABI 2023)
Brome sterile (French) (CABI 2023)
Pin yu que mai (贫育雀麦 Chinese) (eFloras 2023)

Barren Brome (Bromus sterilis) florets

  • Barren Brome (Bromus sterilis) florets

  • Barren Brome (Bromus sterilis) floret

  • Barren Brome (Bromus sterilis), palea teeth

  • Bromus sterilis (barren brome) close up of callus and callus hairs. Scale in mm.

  • Bromus sterilis (barren brome) close up of callus scar. Scale in mm.

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Overview

Aperçu

Regulation :

Remarques Réglementation:

  • Quarantine lists of countries e.g. Mexico *may be updated without notice

Regulation Notes:

  • Bromus sterilis on Mexico list of harmful organisms (USDA-PCIT-PExD 2023) (*may be updated without notice).
  • Bromus sterilis on Colombia list of harmful organisms (USDA-PCIT-PExD 2023) (*may be updated without notice).
  • Bromus sterilis on Nicaragua list of harmful organisms (USDA-PCIT-PExD 2023) (*may be updated without notice).
  • Bromus sterilis on Peru list of harmful organisms (USDA-PCIT-PExD 2023) (*may be updated without notice).

Distribution :

Répartition :

Bromus sterilis is native to Northern Africa, temperate Asia and Europe and has been introduced and naturalized in Australasia, Chile, Canada, the western and eastern states within the United States, including Hawaii, but is mostly absent from the Great Plains (Pavlick 1995; Barkworth et al. 2007; USDA-ARS-NPGS 2023; USDA-NRCS 2023).

Habitat and Crop Association :

Habitat et Cultures Associées :

Bromus sterilis can be found in meadows, fields, overgrazed rangelands, along roadsides, and in other disturbed areas (Barkworth et al. 2007; CABI 2023) and is reported as a troublesome weed of winter cereals, especially Hordeum vulgare subsp. vulgare (barley) and Triticum aestivum subsp. aestivum (common wheat), in Brassica spp. (oil seed rape), in vineyards, and in other cultivated plants (Žďarkova et al. 2014; Bayer CropScience 2015).

Economic Use, cultivation area, and Weed Association :

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

Duration of Life Cycle :

Durée du cycle vital:

Annual

Dispersal Unit Type :

Type d’unité de dispersion :

Floret

General Information

RENSEIGNEMENTS GÉNÉRAUX

Bromus sterilis has become a weedy invasive species in many temperate regions of the world (CABI 2023). This species is reported to aggressively out-compete native species for resources and during the summer months the dried plant litter can provide conditions for high-intensity wildfires (GOERT 2023). B. sterilis is a prolific seed producer (Bayer CropScience 2015; GOERT 2023), has a short primary dormancy period, and a high seedling emergence from shallow soil depths of 2 – 4 cm (Žďarkova et al. 2014). These characteristics have allowed B. sterilis to become a troublesome annual weed in crops grown in reduced tillage systems (Žďarkova et al. 2014).

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Identification

Identification

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  • Spikelet

    Size

    • Spikelet length: 20 – 35 mm; width: 4 – 8 mm (Tutin et al. 1980; Barkworth et al. 2007; eFloras 2023).
    • Lower (1st) glume length: 6 – 14 mm; upper (2nd) glume length: 10 – 20 mm (Pavlick 1995; Barkworth et al. 2007).

    Shape

    • Spikelets oblong to wedge-shaped, slightly laterally compressed (Barkworth et al. 2007; eFloras 2023).

    Surface Texture

    • Glumes and florets papery, margins thin and translucent (hyaline).
    • Surface of glumes glabrous or with short stiff hairs.
    • Lower (1st) glume 1(3)-nerved; upper (2nd) glume 3(5)-nerved (Pavlick 1995; Barkworth et al. 2007).

    Colour

    • Spikelet colour light yellowish brown, sometimes with purple tinge.

    Other Features

    • Spikelet composed of 5 – 9 similar looking florets (Tutin et al. 1980; Pavlick 1995).
    • Florets furthest away from spikelet base (distal florets) are usually sterile and slightly smaller in size.
    • Disarticulation of the spikelet occurs above the glumes and between the florets at the rachilla nodes.

  • Floret

    Size

    • Floret length*: 14 – 19 mm (average 17 mm); width 1.2 – 1.8 mm (average 1.5 mm).
    • Floret length**: 10.1 – 20.3 mm (average 15.7 mm); width: 1.3 – 1.9 mm (average 1.4 mm).
    • Lemma teeth length*: 1.7 – 2.5 mm (average 2.2 mm).
    • Palea extends beyond the tip of the caryopsis.
    • Rachilla length*: 2.3 – 2.6 mm (average 2.4 mm).
    • Callus length*: 0.5 – 0.7 mm (average 0.6 mm).
    • Awn length*: 13 – 20 mm (average 16 mm); awn attached about 1.5 mm below lemma tip.
    *Note: Minimum and maximum based on a random selection of 10 florets in normal range of this species using image measurement protocol (ISMA 2020). CDA-S-22355. Measurements by D. J. Lionakis Meyer.
    **Note: Minimum and maximum based on a random selection of 10 florets in normal range of this species using image measurement protocol (ISMA 2020). Measurements by CFIA staff.

    Measurements from the literature:
    • Lemma length: 13 – 15 mm (Musil 1963).
    • Lemma length: 14 –20 mm; width: 2 – 4 mm; lemma teeth length: 1 – 3 mm; awn length: 15 – 30 mm; palea length almost equal to lemma (Tutin et al. 1980).
    • Lemma length: 12 – 18 mm; width: 1.7 – 2 mm; awn is equal in length to lemma (Bojňanský and Fargašová 2007).
    • Lemma length: 9 – 15 (20) mm; lemma teeth length: 0 – 3 mm: awm length: 15 – 30 mm (DiTomaso and Healy 2007).
    • Lemma length: 13 – 20 mm; awn length 15 – 35 mm (Baldwin et al. 2012; CABI 2023).
    • Awn length reported up to 35 mm (Baldwin et al. 2012; CABI 2023).

    Shape

    • Floret shape narrowly teardrop-shaped (lanceolate), slightly arched toward lemma.
    • Lemma back rounded, apex split into 2 teeth (bifid).
    • Awn straight.
    • Callus pointed, scar oval.
    • Rachilla round in cross-section and flattened at apex, detachment (disarticulation) scar usually oval.

    Surface Texture

    • Lemma and palea are papery with thin and translucent (hyaline) margins.
    • Lemma 7 (9)–nerved, nerves forming raised longitudinal ridges.
    • Lemma teeth thin and translucent (hyaline).
    • Lemma surface covered with short stiff hairs that are rough to the touch, hairs near base slightly longer.
    • Palea mostly glabrous between keels, palea keels with stiff, wide-spaced hairs (palea teeth).
    • Awn covered with short stiff hairs.
    • Rachilla covered with short stiff hairs.
    • Callus glabrous.

    Colour

    • Floret colour light yellowish brown with or without purple tinge, margins of lemma a lighter shade of yellowish brown compared to main body.

    Barren Brome (Bromus sterilis) florets

  • Caryopsis

    Size

    • Caryopsis length*: 10.2 – 11.3 mm (average 10.7 mm); width: 1.0 – 1.1 mm (average 1.0 mm).
    • Hilum length*: 8.9 – 10.2 mm (average 9.5 mm).
    *Note: minimum and maximum based on a random selection of 2 caryopses in normal range of this species using image measurement protocol (ISMA 2020). CDA-S-22347.

    Caryopsis size measurements from the literature:
    • Caryopsis length: 8 – 9 mm; width: 1.5 – 1.7 mm (Bojňanský and Fargašová 2007).

    Shape

    • Caryopsis shape linear, dorsoventrally compressed, flat to folded into a V-shape in cross-section, pointed at embryo end.

    Surface Texture

    • Caryopsis surface texture smooth to striate, apex fleshy and hairy, lemma and palea may adhere to the caryopsis.

    Colour

    • Caryopsis colour usually dull reddish-brown, occasionally purple.

    Other Features

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

    Size

    • Embryo length*: 1.9 – 2.6 mm (average 2.3 mm).
    • Embryo about one-fifth the length of the caryopsis.
    *Note: minimum and maximum based on a random selection of 3 caryopses in normal range of this species using image measurement protocol (ISMA 2020). CDA-S-22347.

    Shape

    • Embryo diamond-shaped to teardrop shaped.

    Endosperm

    • Endosperm solid (Terrell 1971).

    Other Features

    • Embryo in lateral position (Martin 1946).

Identification Tips

CONSEILS POUR L’IDENTIFICATION

The genus Bromus is divided into five sections, in Section Genea (Barkworth et al. 2007) or subgenus Stenobromus (USDA-ARS-NPGS 2023), of which Bromus sterilis and similar species B. diandrus, B. madritensis, B. rubens, and B. tectorum. All five species in the section/ subgenus are classified as harmful organisms or noxious weed seeds in various countries (USDA-AMS 2023; USDA-PCIT-PExD 2023).

Similarities of florets and caryopses among the members of this group include:

  • Florets are linear or narrowly teardrop shaped (lanceolate) and rounded over the mid-nerve of the lemma.
  • Florets and caryopses are dorsoventrally compressed to slightly in-rolled or folded (U-shaped to V-shaped in cross-section).
  • The lemma teeth are thin and translucent (hyaline) and one or more millimeters long.
  • The awn is usually longer than the lemma, stiff, straight or arched, and is attached 1.5 mm or more below the tip of the lemma.

The florets of Bromus sterilis are distinguished from Bromus diandrus by their smaller size and longitudinally folded caryopsis (nearly V-shaped in cross-section). Florets of this species are generally distinguished from the other similar species by having shorter hairs covering the lemma and shorter hairs along the palea keels.

Barren Brome (Bromus sterilis) floret

Additional Botany Information

AUTRES RENSEIGNEMENTS BOTANIQUES

Flowers/Inflorescence

  • Inflorescence drooping with spreading branches that are mostly longer than the spikelets, 10 – 20 cm long and 5 – 12 cm wide, 1 – 3 spikelets per branch (Tutin et al. 1980; Barkworth et al. 2007).

Vegetative Features

  • Plants annual with fibrous roots, stems up to 100 cm tall; stems without hairs; leaves and sheaths hairy (Tutin et al. 1980; Barkworth et al. 2007; eFloras 2023).

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.

Bromus diandrus Roth (ripgut brome) florets are longer (24 – 29 mm, average 27 mm*; 17.3 – 21.4 mm, average 26 mm**) than B. sterilis; the callus of B. diandrus is longer (0.8 – 1.2 mm*), the attachment scar is circular to oval; the caryopses are U-shaped in cross-section. B. diandrus (and its synonyms) is listed as a harmful organism in Colombia, Peru, Brazil, China, Panama, and Paraguay (USDA-PCIT-PExD 2023), and is a regulated weed seed in Wyoming, USA (USDA-AMS 2023).

Mature florets of Bromus madritensis L. (compact brome) are about the same length (14 – 19 mm, average 15 mm*) as B. sterilis but they are strongly arched towards the lemma side, the palea keel hairs (palea teeth) are long ciliate and widely spaced, the caryopses are only slightly in-rolled longitudinally and are strongly arched toward the embryo side. B. madritensis is listed as a harmful organism in Colombia, Nicaragua, and Peru (USDA-PCIT-PExD 2023).

Florets of Bromus rubens L. (red brome or foxtail chess) are slightly smaller (12.6 – 15.2 mm, average 14 mm*) than B. sterilis; the entire lemma is covered with long stiff hairs that increase in length towards the lemma tip; the palea keel hairs (palea teeth) are long ciliate and widely spaced; the caryopses are broadly U-shaped in cross-section. B. rubens is listed as a harmful organism in Colombia and Peru (USDA-PCIT-PExD 2023).

Florets of Bromus tectorum L. (downy brome) are shorter (11 – 12.3 mm, average 11.6 mm*; 8.9 – 13.3 mm, average 11.6 mm**) than B. sterilis; long stiff hairs cover the lower two-thirds of the lemma and long soft hairs, about 1 mm long, cover the upper one-third of the lemma; the palea is membranous, palea keel hairs (palea teeth) are long ciliate and widely spaced; caryopses are dark purple coloured, flat or slightly in-rolled or strongly in-rolled and V-shaped in cross-section in the lower half while flattened in the upper half. B. tectorum is listed as a harmful organism in Australia, Brazil, Nauru, Peru, and Taiwan (USDA-PCIT-PExD 2023), a Secondary Noxious Weed in Canada (GC 2016), and is a regulated weed seed in Wyoming, USA (USDA-AMS 2023).

* Note: Minimum and maximum of 10 florets in a normal range of this species using image measurement protocol (ISMA 2020). Measurements by D. J. Lionakis Meyer.
**Note: Minimum and maximum of 10 florets in a normal range of this species using image measurement protocol (ISMA 2020). Measurements by CFIA staff.

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Reference(s)

Référence(s)

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

Baldwin, B. G., Goldman, D. H., Keil, D. J., Patterson, R., Rosatti, T. J., Wilken, D. H. (Eds.). 2012. The Jepson Manual: Vascular Plants of California. 2nd Edition. University of California Press, Berkeley and Los Angeles, CA.

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.

Bayer CropScience. 2015. Bayer Expert Guide: Brome Management in Cereals. Agri Services. https://cropscience.bayer.co.uk/mediafile/100474523/m27534_brome_expert_guide_2015_210x148.pdf

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 sterilis (barren brome). CABI Invasive Species Compendium. https://www.cabidigitallibrary.org/doi/full/10.1079/cabicompendium.10035  Accessed March 3, 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.

eFloras. 2022. Flora of China. www.efloras.org. Accessed July 28, 2022.

Garry Oak Ecosystem Recovery Team (GOERT). 2023. Bromus rigidus and B. sterilis. https://goert.ca/wp/wp-content/uploads/IS-factsheet-bromus-rigidus-sterilis.pdf  Accessed March 7, 2023.

Government of Canada (GC). 2016. Canadian Weed Seeds Order. https://laws-lois.justice.gc.ca/eng/regulations/SOR-2016-93/page-2.html (English) https://laws-lois.justice.gc.ca/fra/reglements/DORS-2016-93/page-2.html (French)  Accessed April 13, 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.

Musil, A. F. 1963. Identification of Crop and Weed Seeds. Agriculture Handbook No. 219. U. S. Department of Agriculture. Washington, D.C.

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.

Terrell, E. E., Hill, S. R., Wiersma, J. H., and Rice, W. E. 1986. A Checklist of Names for 3,000 Vascular Plants of Economic Importance. U. S. Dept. Agric., Agric. Res. Service, Agric. Handbook No. 505.

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). 2022. 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 February 15, 2023.

United States Department of Agriculture-Agricultural Research Service-National Plant Germplasm System (USDA-ARS-NPGS). 2023. USDA, Agricultural Research Service, National Plant Germplasm System. Germplasm Resources Information Network (GRIN Taxonomy). National Germplasm Resources Laboratory, Beltsville, Maryland. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomydetail?id=7875.  Accessed February 15, 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 March 6, 2023.

United States Department of Agriculture-Phytosanitary Certificate Issuance and Tracking System-Phytosanitary Export Database (USDA-PCIT-PExD). 2023. Phytosanitary import requirements of U.S.-origin commodities to foreign countries. https://pcit.aphis.usda.gov/PExD/faces/ViewPExD.jsf  Accessed February 15, 2023.

Žďarkova, V., Hamouzova, K., Holec, J., Janků, J., and Soukup, J. 2014. Seed ecology of Bromus sterilis. Julius-Kühn-Archiv. DOI 10.5073/jka.2014.443.018

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 Taran Meyer for seed imaging.

contactus@idseed.org

Last updated
on 2023-03-27

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