Fact Sheets


Bothriochloa ischaemum (L.) Keng

Family :

Famille :


Synonym(s) :

Synonyme(s) :

Andropogon ischaemum L. (ITIS 2021)

Common Name(s) :

Nom(s) commun(s) :

Yellow bluestem
(English) (GC 2016)

Chiendent à balai (French) (GC 2016)

Bai yang cao (Chinese) (CABI 2021)

  • Yellow bluestem (Bothriochloa ischaemum) spikelets

  • Yellow bluestem (Bothriochloa ischaemum) spikelets

  • Yellow bluestem (Bothriochloa ischaemum) spikelet, inner side

  • Yellow bluestem (Bothriochloa ischaemum) spikelet, outer side

  • Yellow bluestem (Bothriochloa ischaemum) spikelet, showing teeth along sides of bract

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Regulation :

Remarques Réglementation:

  • CFIA Weed Seeds Order - Class 1: Prohibited Noxious Weed Seeds

Regulation Notes:

Prohibited Noxious, Class 1 in the Canadian Weed Seeds Order (2016) under the Seeds Act. All imported and domestic seed must be free of Prohibited Noxious weed seeds.

Distribution :

Répartition :

Native to Asia and southern Europe and introduced in Australia, Mexico, parts of South America, and the United States (Celarier and Harlan 1958 ). Absent from Canada (Brouillet et al. 2010+).

Habitat and Crop Association :

Habitat et Cultures Associées :

Borders of fields, pastures, rangelands, dry stony places, roadsides and waste ground. Often abundant along roads, it tends to spread outwards from roadsides and into new areas (Barkworth et al. 2003).

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:


Dispersal Unit Type :

Type d’unité de dispersion :


General Information


Bothriochloa ischaemum was introduced into millions of hectares of rangeland in the United States in the early 1900s as a forage crop and soil stabilizer, and plantings continue in marginal rangeland and roadsides (Barkworth et al. 2003; CABI 2021).

Dense stands formed by B. ischaemum tend to eliminate native species, alter the soil microbes and impact wildlife biodiversity and habitat availability (CABI 2021). The plants spread from plantings, infesting surrounding roadsides and native rangeland (Barkworth et al. 2003).


Bothriochloa ischaemum infestation (John M. Randall, The Nature Conservancy, Bugwood.org)



  • Spikelet


    • Spikelet length* : 4.0 – 5.2 mm; width: 0.8 – 1.0 mm
    *Note: minimum and maximum of 10 spikelets in a normal range of this species using image measurement (ISMA 2020)


    • Spikelet is long oval shaped, compressed in edge view

    Surface Texture

    • Spikelet surface is smooth, but the side opposite the stalks has longitudinal ridges


    • Spikelet is dull or shiny light yellow with purple tips

    Other Features

    • A pair of stalks (a pedicel and rachis segment) edged with long white hairs (length: 1.0 – 3.0 mm; Barkworth et al. 2003) extend 3/4 up the spikelet, each with a central groove more narrow than the edges
    • A sterile spikelet may be attached to one of the stalks that is a similar size and shape to the fertile spikelet but without stalks, longitudinally ridged and flattened in edge view with a papery consistency
    • Short teeth are along the edges at the narrow end of the spikelet
    • The upper, or second glume is keeled with a central ridge with the stalks arranged on either side
  • Floret


    • Floret is same size as the spikelet 


    • Floret is long oval shaped

    Surface Texture

    • Floret has a smooth surface


    • Floret is colourless and transparent 

    Other Features

    Lemma awns

    • A long awn (length: 9.0 – 17.0 mm; Barkworth et al. 2003) is attached to the lemma, extending beyond the glumes of the spikelet

    Other features

    • The lemma of the floret is rudimentary, and surrounds the awn
    • The palea is as long as the spikelet with hairs along the edges
  • Caryopsis 


    • Caryopsis length*: 1.5 – 2.0 mm; width: 0.7 – 0.8 mm 
     *Note: minimum and maximum of 5 caryopses in a normal range of this species using specimen measurement (ISMA 2020)


    • Caryopsis is narrow oval shaped, compressed

    Surface Texture

    • Caryopsis has a wrinkled surface, with grooved grid reticulation visible under high magnification


    • Caryopsis is dull translucent yellow coloured 

    Other Features

    • Hilum is a brown spot at the embryo end on the opposite side
  • Embryo


    • Embryo is a rudimentary size compared to the caryopsis


    • Embryo is oval shaped, lateral position


    • Endosperm is hard and translucent whitish coloured

Identification Tips


Many species in the Bothriochloa genus have a similar size, shape and colour. The distinguishing features between the species are found on the paired stalks and the glumes of the spikelet. B. ischaemum can be distinguished by a longitudinally ridged glume with purple tips opposite the stalks. The stalks have hairs generally 1.0 – 3.0 mm long, and a more narrow central groove compared to similar species (Barkworth et al. 2003).

Additional Botany Information


Similar Species


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.

Bothriochloa bladhii (Retz.) S. T. Blake (Australian bluestem)

B. bladhii spikelets may have a reddish cast, purple streaks, or both on the glumes. The side opposite the stalks of B. bladhii is often dull with short, scattered hairs and occasionally may have a central pit. The stalks have shorter, sparse hairs (length: 0- 1.0 mm; Barkworth et al. 2003) and a darker central groove compared to B. ischaemum.

Bothriochloa laguroides (DC.) Herter (silver beardgrass)

B. laguroides spikelets (length*: 2.9 – 4.4 mm) are generally shorter than B. ischaemum. The glume opposite the stalks lacks ridges, is a uniform colour, occasionally has a central pit, and the teeth appear shorter. The hairs on the stalk are longer (length: 3.0 – 9.0 mm) compared to B. ischaemum (Barkworth et al. 2003) and the central groove is wider.

Note* minimum and maximum of 5 spikelets in a normal range of this species using specimen measurement (ISMA 2020)

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Barkworth, M. E., K. M. Capels, S. Long, and M.B. Piep, (eds.) 2003. Flora of North America Volume 25. Magnoliophyta: Commelinidae (in part): Poaceae, part 2. Oxford University Press, New York, New York.

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 May 30, 2016.

Centre for Agriculture and Bioscience International (CABI). 2021. Invasive Species Compendium, CAB International, Wallingford, UK. https://www.cabidigitallibrary.org/journal/cabicompendium Accessed March 04, 2021.

Celarier, R.P and Harlan, J.R. 1958. The cytogeography of the Bothriochloa ischaemum complex. Gramineae. I. Taxonomy, and Geographic Distribution. Botanical Journal of the Linnean Society 755-760.

Flora of North America (FNA) Editorial Committee, eds. 1993+. Flora of North America North of Mexico [Online]. 22+ vols. New York and Oxford.  Accessed December 29, 2022.

Global Biodiversity Information Facility (GBIF) Secretariat. 2022. https://doi.org/10.15468/39omei Accessed via https://www.gbif.org/species/2704102 Accessed December 29, 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)

Integrated Taxonomic Information System (ITIS). 2021. https://www.itis.gov/ Accessed March 04, 2021

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



Jennifer Neudorf, Angela Salzl, Ruojing Wang, Karen Castro, Katrina Entwistle

Canadian Food Inspection Agency