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Bromus diandrus Roth

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Family :

Famille :

Poaceae

Synonym(s) :

Synonyme(s) :

Synonyms for Bromus diandrus Roth var. diandrus:
Bromus diandrus Roth subsp. diandrus (USDA-ARS-NPGS 2023)
Bromus rigidus Roth var. gussonei (Parl.) Coss. & Durieu (USDA-NRCS 2023)
Bromus gussonei Parl. (USDA-NRCS 2023)
Anisantha diandra (Roth) Tutin ex Tzvelev (USDA-NRCS 2023)

Synonyms for Bromus diandrus Roth var. rigidus (Roth) Sales:
Bromus rigidus Roth (basionym) (USDA-ARS-NPGS 2023; USDA-NRCS 2023)
Anisantha rigida (Roth) Hyl. (USDA-ARS-NPGS 2023; USDA-NRCS 2023)
Bromus diandrus Roth ssp. rigidus (Roth) Lainz (USDA-NRCS 2023)
Bromus diandrus Roth subsp. rigidus (Roth) O. Bolòs et al. (USDA-ARS-NPGS 2023)
Bromus rigidus Roth subsp. rigidus (USDA-ARS-NPGS 2023)
Bromus rigidus Roth var. rigidus (USDA-ARS-NPGS 2023)

Common Name(s) :

Nom(s) commun(s) :

Ripgut brome

Common names for Bromus diandrus var. diandrus
Ripgut brome (English) (USDA-NRCS 2023)
Broncho grass (English) (USDA-ARS-NPGS 2023)
Great brome (English) (Pavlick 1995; CABI 2023a; USDA-ARS-NPGS 2023)
Hohe Trespe (German) (USDA-ARS-NPGS 2023)
Bromo (Spanish) (CABI 2023a)
Brome raide (French) (CABI 2023a)
Espigao (Portuguese) (CABI 2023a)

Common names for Bromus diandrus var. rigidus
Ripgut brome (English) (Wiersema and León 1999; AOSA 2023; USDA-NRCS 2023)
Broncograss (English) (CABI 2023b)
Great brome (English) (CABI 2023b)
Lesser bromegrass (English) (CABI 2023b)
Rigid brome (English) (CABI 2023b)
Ripgut bromegrass (English) (CABI 2023b)
Ripgut grass (English) (Pavlick 1995; Wiersema and León 1999)
Steife Trespe (German) (USDA-ARS-NPGS 2023)
Barba de macho (Spanish) (CABI 2023b)
Brome rigide (French) (CABI 2023b)
Espanada (Portuguese) (CABI 2023b)
Fura-capa (Portuguese) (CABI 2023b)
ying que mai (硬雀麦 Chinese) (efloras 2023)

Bromus diandrus (ripgut brome) florets and caryopses

  • Bromus diandrus (ripgut brome) florets and caryopses

  • Bromus diandrus (ripgut brome) floret

  • Bromus diandrus (ripgut brome) floret

  • Bromus diandrus (ripgut brome) floret

  • Bromus diandrus (ripgut brome) close up view of lemma teeth and awn base. Scale in mm.

  • Bromus diandrus (ripgut brome) close up view of palea keel hairs (palea teeth). Scale in mm.

  • Bromus diandrus (ripgut brome) close up view of callus and callus hairs. Scale in mm.

  • Bromus diandrus (ripgut brome) close up view of the rachilla and callus scar. Scale in mm.

  • Bromus diandrus (ripgut brome) caryopsis in embryo view. Scale in mm.

  • Bromus diandrus (ripgut brome) close up view of embryo. Scale in mm.

  • Bromus diandrus (ripgut brome) caryopsis in hilum view. Scale in mm.

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Overview

Aperçu

Regulation :

Remarques Réglementation:

  • ​Quarantine lists of countries e.g. China *may be updated without notice
  • USA Federal Noxious Weed Seed List

Regulation Notes:

  • Bromus diandrus on Colombia list of harmful organisms (USDA-PCIT-PExD 2023) (*may be updated without notice).
  • Bromus diandrus ssp. rigidus on Peru list of harmful organisms (USDA-PCIT-PExD 2023) (*may be updated without notice).
  • Bromus rigidus on Brazil, China, Panama, and Paraguay lists of harmful organisms (USDA-PCIT-PExD 2023) (*may be updated without notice).
  • Bromus diandrus var. rigidus is a regulated weed seed in Wyoming USA if found as a contaminant in agricultural or vegetable seed or screenings thereof exceeding 1,200 seeds per pound (USDA-AMS 2022).

Distribution :

Répartition :

Bromus diandrus is indigenous to the Mediterranean region and is native to regions of Northern Africa including the Macaronesia, Temperate Asia and Southern and Western Europe (CABI 2023a, 2023b; USDA-ARS-NPGS 2023). It has been introduced to regions of Southern and Eastern Africa, Central and Northern Europe, North America, Southern South America and Oceania (CABI 2023a, 2023b; USDA-ARS-NPGS 2023).

In North America, B. diandrus is found primarily in the Pacific region from southern British Columbia to Baja California Mexico, extending eastward into Arizona, Colorado, Montana, Nevada, and New Mexico, and is found in scattered populations elsewhere in the United States, and near Edmonton, Alberta, Canada (Barkworth et al. 2007; Brouillet et al. 2010+; USDA-NRCS 2023).

Habitat and Crop Association :

Habitat et Cultures Associées :

Bromus diandrus is found on disturbed lands such as waste places, fallowed fields and shallowly tilled crop land, roadsides, rangelands, orchards, forestry sites, and in natural plant communities displacing native species (CABI 2023a, 2023b; University of California 2016; Borger et al. 2021). It is most commonly found in areas with a Mediterranean climate typified by mild wet winters and hot dry summers (CABI 2023b).

Bromus diandrus is problematic in cultivated species resulting in lower crop yield, particularly in cereal grains, such as Triticum aestivum subsp. aestivum (wheat) and Hordeum vulgare (barley) (Borger et al. 2021).

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

As treated in North America, Bromus diandrus includes B. diandrus var. diandrus and B. diandrus var. rigidus (Barkworth et al. 2007; DiTomaso and Healy 2007; USDA-ARS-NPGS 2023); whereas these two varieties of B. diandrus are treated separately by some authors in other regions of the world (Tutin et al. 1980; Peltzer et al. 2018; Borger et al. 2021; CABI 2023a, CABI 2023b; eFloras 2023).

While the morphological features of the two varieties of B. diandrus overlap, according to authors recognizing two separate species (i.e., B. diandrus and B. rigidus), the two are distinguished by B. diandrus having a loose and nodding inflorescence in which the spikelet branches are longer than the spikelets, the floret callus is less than 1 mm long, and the callus scar is circular; whereas, for B. rigidus the inflorescence is compact and stiff with the spikelet branches shorter than the spikelets, the floret callus is longer than 1 mm, and the callus scar is more or less oval (Tutin et al. 1980; Peltzer et al. 2018; Borger et al. 2021; CABI 2023b).

Bromus diandrus is a prolific seed producer. Populations from Australia, France, Israel, New Zealand, and Spain produced 1196-2729 seeds per plant (Borger et al. 2021). B. diandrus has an initial period of after-ripening or dormancy and many dormant seeds survive the hot, dry summers, but can become non-viable in a humid environment (Peltzer et al. 2018).

This species is found as a contaminant of wool and seed lots and is known to cause injury to livestock and herding animals with sharp pointed florets entering the eyes, nose, mouth, feet, and digestive tract (DiTomaso and Healy 2007; Peltzer et al. 2018; CABI 2023a, 2023b).

.

Identification

Identification

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  • Spikelet

    Size

    • Spikelet length: 25 – 70 mm (Tutin et al. 1980; Barkworth et al. 2007).
    • Lower (1st) glume length: 15 – 25 mm; upper (2nd) glume length: 20 – 25 mm (Barkworth et al. 2007).

    Shape

    • Spikelets narrowly wedge-shaped and laterally compressed (Barkworth et al. 2007; eFloras 2023).

    Surface Texture

    • Glumes and florets papery, surface scabrous or smooth, margins thin and translucent (hyaline).
    • Lower (1st) glume with 1 – 3 nerves; upper (2nd) glume with 3 – 5 nerves (Barkworth et al. 2007).

    Colour

    • Floret colour brownish yellow to purplish-brown, margins of lemma lighter in color compared to main body.

    Other Features

    • Spikelet composed of 4 – 11 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 the glumes and between the florets at the rachilla nodes.

  • Floret

    Size

    • Floret length*: 24 – 29 mm (average 27 mm); width*: 1.2 – 1.8 mm (average 1.5 mm).
    • Floret length**: 17.3 – 21.4 mm (average 26.0 mm); width: 1.3 – 3.1 mm (average 2.1 mm).
    • Lemma teeth length*: 3.4 – 5.9 mm (average 4.9 mm).
    • Palea is shorter than the lemma.
    • Rachilla length*: 3.3 – 4.1 mm (average 3.8 mm).
    • Callus length*: 0.8 – 1.2 mm (average 1.0 mm).
    • Awn length*: 18 – 27 mm (average 21 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-22306.
    **Note: Minimum and maximum based on a random selection of 10 florets in a normal range of this species using image measurement protocol (ISMA 2020). Measurements by CFIA staff.

    Floret size measurements from the literature:
    • Lemma length 25 – 30 mm; lemma length about eight times the width (Musil 1963).
    • B. diandrus lemma length 20 – 35 mm, awn length: 35 – 65 mm; B. rigidus lemma length: 22 – 25 mm, awn length: 30 – 50 mm (Tutin et al. 1980).
    • Lemma length 20 – 35 mm; lemma teeth length 3 – 5 mm; awn length 30 – 65 mm (Barkworth et al. 2007).
    • Lemma body length: 18 – 35 mm; lemma teeth length 3 – 7 mm; lemma awn length: 30 – 65 mm (DiTomaso and Healy 2007).
    • Floret length 18 – 22 mm; width 1.9 – 2.1 mm; awn length: up to 5 mm (Bojňanský and Fargašová 2007).
    • Awn length reported up to 65 mm (Barkworth et al. 2007; DiTomaso and Healy 2007).

    Shape

    • Florets long, narrowly teardrop shaped (linear-lanceolate), slightly arched backwards.
    • Lemma back rounded, apex split into 2 teeth (bifid).
    • Awn straight.
    • Callus sharply pointed; attachment point circular (usually in B. diandrus var. diandrus) to oval (usually in B. diandrus var. rigidus) (Tutin et al. 1980; eFloras 2023).
    • Rachilla round in cross-section and flattened at apex, detachment (disarticulation) scar circular to oval.

    Surface Texture

    • Lemma and palea are papery with thin and translucent (hyaline) margins.
    • Lemma 7–nerved, mid-vein more visible than others, margins and lemma teeth thin and translucent (hyaline), surface covered with short stiff hairs that are rough to the touch.
    • Awn covered with short stiff hairs.
    • Callus glabrous, hairs above callus slightly longer than those on lemma back.
    • Rachilla covered with short stiff hairs.
    • Palea mostly glabrous between keels, palea keels with stiff and widely spaced hairs (palea teeth).

    Colour

    • Floret colour yellowish brown to purplish brown, margins of lemma lighter brown in color compared to main body.

    Bromus diandrus (ripgut brome) florets and caryopses

  • Caryopsis

    Size

    • Caryopsis length*: 12 – 12.7 mm (average 12.3 mm); width*: 1.4 – 1.6 mm (average 1.5 mm).
    • Hilum length*: 10.6 – 11.4 mm (average 11.1 mm).
    *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-22305.

    Caryopsis size measurements from the literature:
    • Caryopsis length 6.2 – 7 mm; width 1.8 – 2 mm (Bojňanský and Fargašová 2007).

    Shape

    • Caryopsis shape linear, dorsoventrally compressed, flat to U-shaped in cross-section, pointed at embryo end.

    Surface Texture

    • Surface of caryopsis smooth to striate, lemma and palea may adhere to the caryopsis.

    Colour

    • Caryopsis colour reddish-brown to purplish-brown.

    Other Features

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

    Bromus diandrus (ripgut brome) caryopsis in embryo view. Scale in mm.

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  • Embryo

    Size

    • Embryo length*: 1.8 – 2.0 mm (average 1.9 mm).
    • Embryo about one-fifth the length of 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-22305.

    Shape

    • Embryo narrowly diamond or teardrop shaped.

    Endosperm

    • Endosperm solid (Terrell 1971).

    Other Features

    • Embryo in lateral position (Martin 1946).

    Bromus diandrus (ripgut brome) close up view of embryo. Scale in mm.

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 diandrus and similar species B. madritensis, B. rubens, B. sterilis, 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 diandrus are distinguished from B. sterilis by their larger size and longitudinally in-rolled caryopsis (U-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.

Bromus diandrus (ripgut brome) floret

Additional Botany Information

AUTRES RENSEIGNEMENTS BOTANIQUES

Flowers/Inflorescence

  • Inflorescence is an upright or drooping panicle, up to 20 to 25 cm long (Pavlick 1995; Barkworth et al. 2007; DiTomaso and Healy 2007).

Vegetative Features

  • Plants annual with fibrous roots, stems up to 90 cm tall, leaves and stems below inflorescence hairy (Barkworth et al. 2007; 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.

Bromus sterilis L. (sterile brome) florets are shorter (14 – 19 mm; average 17 mm*; floret length**: 10.1 – 20.3 mm, average 15.7 mm**) than B. diandrus; the callus of B. sterilis is shorter (0.5 – 0.7 mm*), the attachment scar is round, oval, or egg-shaped; the caryopses are V-shaped in cross-section. B. sterilis is listed as a harmful organism in Colombia, Mexico, Nicaragua, and Peru (USDA-PCIT-PExD 2023).

Mature florets of Bromus madritensis L. (compact brome) are shorter (14 – 19 mm, average 15 mm*) than B. diandrus and 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 smaller (12.6 – 15.2 mm, average 14 mm*) than B. diandrus; 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. diandrus; 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 (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.

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.

Borger, C. P. D., Torra, J., Royo-Esnal, A., Davies, L. & Newcombe, G. 2021. Chapter 4 – Bromus diandrus and Bromus rigidus in B. S. Chauhan (Ed.) Biology and Management of Problematic Crop Weed Species (2021): pp. 67-88. https://doi.org/10.1016/B978-0-12-822917-0.00004-5.

Brouillet, L., Coursol, F., Meades, S. J., Favreau, M., Anions, M., Bélisle, P. and Desmet, P. 2010+. VASCAN, the database of vascular plants of Canada. http://data.canadensys.net/vascan/  Accessed February 15, 2023.

Center for Agriculture and Bioscience International (CABI). 2023a. Bromus diandrus (great brome). CABI Invasive Species Compendium. https://www.cabi.org/isc/datasheet/10024.  Accessed February 6, 2023.

Center for Agriculture and Bioscience International (CABI). 2023b. Bromus rigidus (ripgut brome). CABI Invasive Species Compendium. https://www.cabi.org/isc/datasheet/10032.  Accessed February 6, 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.

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 October 10, 2022.

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.

Peltzer, S., Borger, C. and Hashem, A. 2018. Brome grass. Government of Western Australia Department of Primary Industries and Regional Development Agriculture and Food. https://www.agric.wa.gov.au/grains-research-development/brome-grass. Accessed February 7, 2023.

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.

University of California. 2016. Weed Gallery: Ripgut brome (Bromus diandrus). UCIPM Agriculture and Natural Resources, University of California. http://ipm.ucanr.edu/PMG/WEEDS/ripgut_brome.html.  Accessed February 6, 2023.

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. http://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomydetail?id=432366. Access Date: 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 February 15, 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.

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, Taran Meyer for seed imaging, 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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