Fact Sheets


Sorghum halepense (L.) Pers.

Family :

Famille :


Synonym(s) :

Synonyme(s) :

Holcus halepensis L. (USDA-ARS 2021)

Andropogon halepensis (L.) Brot. (USDA-ARS 2021)

Common Name(s) :

Nom(s) commun(s) :

(English) (Wiersema and León 1999; AOSA 2021; USDA-ARS 2021; USDA-NRCS 2021)
Johnson grass (English) (Barkworth et al. 2003; Darbyshire 2003; USDA-ARS 2021)
Aleppo grass (English) (USDA-ARS 2021)
Herbe d’Alep (French) (Wiersema and León 1999)
Sorgho d’Alep (French) (Wiersema and León 1999; GC 2016)
Aleppohirse (German) (Wiersema and León 1999; CABI 2021)
Wilde Mohrenhirse (German) (USDA-ARS 2021)
Sorgagna (Italian) (USDA-ARS 2021)
Capim-argentino (Portuguese) (CABI 2021)
Cañota (Spanish) (Wiersema and León 1999)
Hierba Johnson (Spanish) (Wiersema and León 1999)
Sorgo de Aleppo (Spanish) (Wiersema and León 1999)
Ogräsdurra (Swedish) (USDA-ARS 2021)
Shi mao (石茅) (Chinese) (eFloras 2021)

  • Johnson grass (Sorghum halepense) spikelets

  • Johnson grass (Sorghum halepense) spikelets

  • Sorghum halepense

  • Johnson grass (Sorghum halepense) spikelet, inner side

  • Johnson grass (Sorghum halepense) spikelet, outer side

  • Johnson grass (Sorghum halepense) spikelet base, inner side

  • Johnson grass (Sorghum halepense) spikelet top showing margin teeth

  • Johnson grass (Sorghum halepense) caryopsis

  • Johnson grass (Sorghum halepense) spikelet (L) and caryopsis (R)

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Regulation :

Remarques Réglementation:

  • CFIA Weed Seeds Order - Class 2: Primary Noxious Weed Seeds
  • ​Quarantine lists of countries e.g. China *may be updated without notice
  • USA Federal Noxious Weed Seed List

Regulation Notes:

A noxious weed seed in at least 34 states within the United States (USDA-AMS 2022).

On Australia, Fiji, Grenada, Nauru, New Zealand, Niue, Panama lists of harmful organisms (USDA-PCIT-PExD 2021) (*may be updated without notice).

Distribution :

Répartition :

Native range for Sorghum halepense is uncertain, possibly native to northeast Africa and western and central Asia as far as India (Warwick and Black 1983; USDA-ARS 2021). The species has been widely introduced and naturalized in warm-temperate regions, including eastern Asia, North and South America, Europe, Africa, and Oceania (CABI 2021). In Canada, it is present in Ontario (Brouillet et al. 2010+). In the United States, it is reported present in 48 of 50 states (USDA-NRCS 2021).

Habitat and Crop Association :

Habitat et Cultures Associées :

As a weed pest, Sorghum halepense can be found in cultivated fields, pastures, orchards, roadsides, and disturbed areas (Darbyshire 2003; CABI 2021). It is a serious weed of many crops, notably cereals (Triticum spp.), Beta vulgaris (sugar beet), Zea mays (maize), Sorghum bicolor (sorghum), Glycine max (soybeans), Phaseolus vulgaris (beans), Gossypium hirstum (cotton), Oryza sativa (rice), Saccharum officinarum (sugarcane), Ruta spp. (citrus), Vitis spp. (grapevine), and others (Holm et al. 1977; CABI 2021).

Economic Use, cultivation area, and Weed Association :

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

Sorghum halepense is sometimes grown as forage crop for pasture or hay (Warwick and Black 1983; Barkworth et al. 2003), but it can cause poisoning of grazing animals under certain environmental conditions because it can produce cyanogenic compounds (Warwick and Black 1983).

Duration of Life Cycle :

Durée du cycle vital:


Dispersal Unit Type :

Type d’unité de dispersion :


General Information


Sorghum halepense has become widely naturalized in North and South America, Australia, New Zealand, Fiji, Hawaii, and other oceanic islands following introduction as a fodder crop during the 1800s and early 1900s and has now become a serious invasive weed pest in many regions (CABI 2021).

Among detrimental effects of this species are allelopathic exclusion of surrounding plants, reduction in crop yield in infested fields, toxicity to grazing animals, eradication difficulties leading to abandonment of arable land, and this species serves as an alternate host for crop plant pathogens and their insect vectors (Holm et al. 1977; CABI 2021). Although grown for forage and hay, the foliage can produce toxic levels of hydrocyanic acid for grazing animals when stressed by drought, exposed to frost, or trampled by livestock (DiTomaso and Healy 2007). This species can serve as an alternate host for plant pathogens that cause sugar cane mosaic virus (SCMV), maize chlorotic dwarf virus (MCDV), corn stunt disease (CS) and other diseases (Warwick and Black 1983).

S. halepense produces abundant seed (up to 28,000 seeds per plant) that shatter readily at maturity and can be carried by wind or rainwater (CABI 2021; Warwick and Black 1983). Dormant seeds can remain viable in the soil for at least seven (CABI 2021) and up to 15 years (DiTomaso and Healy 2007). They also retain their viability after passing through the digestive tract of animals such as birds or cattle (Warwick and Black 1983). The plants produce rhizomes up to 2 m long and can reproduce vegetatively via rhizome fragments as small as 2.5 cm in length (DiTomaso and Healy 2007).


Sorghum halepense plants (Steve Dewey, Utah State University, Bugwood.org)



  • Spikelet (sessile)


    • Sessile spikelet length: 1.8 – 6.3 mm, average 4.5 mm; spikelet width: 1.6 – 2.6 mm, average 1.9 mm (D. Meyer*).
    *Notes: minimum and maximum based on combined 4 samples with a random selection of 40 spikelets in normal range of this species using image measurement protocol (ISMA 2020).
    • Sessile spikelet length: 4.0 – 6.3 mm; spikelet width: 1.6 – 1.9 mm (CFIA**).
    **Notes: minimum and maximum of 20 spikelets in a normal range of this species using image measurement protocol (ISMA 2020).

    Additional size information from literature:

    • Sessile spikelet length: 4.5 – 5.5 mm (Tutin et al. 1980).
    • Sessile spikelet length: 4 – 6 mm; width 1.8 – 2.5 mm (Warwick and Black 1983).
    • Sessile spikelet length: 3.8 – 6.5 mm; width 1.5 – 2.3 mm (Barkworth et al. 2003).
    • Sessile spikelet length: 4 – 5(7) mm; width 1.5 – 2.3 mm (Walters 2011).
    • Sessile spikelet length: 4 – 6.5 mm (Baldwin et al. 2012).


    • Sessile spikelet is narrow egg-shaped tapering to a point at the apex; dorsal-ventrally compressed.

    Surface Texture

    • Sessile spikelet glumes are shell-like (indurate), smooth and glossy, with or without light-coloured appressed hairs.


    • Sessile spikelet is yellow to dark reddish-brown coloured.

    Other Features


    • Glumes completely enclosing the florets, margins of lower glume enclosing the margins of the upper glume.
    • Lower glume keeled along lateral nerves. Hairs along the keels near the tip of the glume are short and stiff.
    • Upper glume keeled along central nerve. Hairs along the keel near the tip of the glume are short and stiff.

    Spikelet callus (spikelet attachment scar)

    • Sessile spikelet callus is usually blunt and surrounded by a ring of hairs.

    Attached spikelet stalks

    • The pair of attached stalks (rachis connecting to the next sessile spikelet above and the pedicel connecting to the pedicellate spikelet) usually have a flared, cup-shaped tip due to the complete abscission type of disarticulation from the spikelets above. This is a key identification character when separating similar species (see below).
    • Attached stalks located on the upper glume side of the spikelet.
    • Margins of stalks hairy.
    • Length of stalks: 0.8 – 4.5 mm, average 2.3 mm (D. Meyer*).
      *Notes: minimum and maximum of 80 spikelet stalks attached to 40 spikelets (2 per spikelet) in a normal range of this species using ISMA image measurement protocol (ISMA 2020).

    Other features

    • Disarticulation of the sessile spikelet occurs below the glumes.
    • Sessile spikelets are deciduous at maturity.
    • The sessile spikelet contains two florets, one fertile and one sterile.
  • Fertile floret of sessile spikelet


    • Fertile lemma length: 2 – 2.5(4) mm (Walters 2011); 4 – 5 mm (Baldwin et al. 2012).


    • Floret is egg-shaped, dorsal-ventrally compressed.

    Surface Texture

    • Floret surface smooth.


    • Floret is white coloured.

    Other Features

    Fertile lemma

    • Fertile lemma two-toothed.
    • Fertile lemma structural thickness hyaline to membranous (thin, transparent to translucent).

    Fertile Palea

    • Fertile palea may be present, absent, or minute.
    • Fertile palea hyaline to membranous.

    Lemma awn

    • Awn may be present or absent on the fertile lemma.
    • Awn bent and twisted.
    • Awn length: 10-16 mm (Tutin et al. 1980), up to 13 mm (Barkworth et al. 2003).
  • Sterile floret of sessile spikelet

    Other Features

    • Sterile lemma hyaline to membranous.
    • Sterile palea is absent.
  • Spikelet (pedicellate)


    Size information from literature:

    • Pedicellate spikelet length: 3.6 – 5.6 mm (Barkworth et al. 2003; Baldwin et al. 2012).
    • Pedicellate spikelet length: 4.5 – 6 mm (Tutin et al. 1980).
    • Pedicellate spikelet length: 4 – 6.5 mm (Walters 2011).


    • Pedicellate spikelet is narrowly tear drop shaped (lanceolate).

    Surface Texture

    • Pedicellate spikelet glumes have a membranous or leathery (coriaceous) structural thickness.


    • Pedicellate spikelet is light yellow or purplish coloured.

    Other Features

    • The pedicellate spikelet may remain attached (via stalk or pedicel) to the sessile spikelet as part of the dispersal unit.
    • The floret of the pedicellate spikelet is staminate (Barkworth et al. 2003)
  • Caryopsis


    • Caryopsis length: 2.4 – 3.2 mm, average 2.7 mm; width: 1.6 – 1.9 mm, average 1.7 mm (Meyer*).
      *Measurement notes: minimum and maximum of 15 caryopses in a normal range of this species using ISMA image measurement protocol (ISMA 2020).
    • Caryopsis length: 2.5 – 3.0 mm (CFIA**); width: 1.3 – 1.5 mm (CFIA**).
      **Measurement notes: minimum and maximum of 10 caryopses in a normal range of this species using image measurement protocol (ISMA 2020).

    Additional size information from literature:

    • Caryopsis length: 2 – 3 mm; width 1.3 – 1.6 mm (Walters 2011).


    • Caryopsis is oval or egg-shaped, dorsal-ventrally compressed.

    Surface Texture

    • Caryopsis surface is smooth.


    • Caryopsis is dull reddish-brown coloured, may be slightly lighter in colour over embryo region.

    Other Features


    • Hilum a dark round spot located in a depression near base of caryopsis.

    Style bases

    • Style bases may remain attached at top of caryopsis.


    • Caryopses not exposed at maturity – completely enclosed by the glumes.
  • Embryo


    • Embryo length: 1.4 – 2.2 mm, average 1.8 mm (D. Meyer*).
    • Embryo about one-half to three-quarters the length of the caryopsis.
    *Notes: minimum and maximum of 15 embryos in a normal range of this species using image measurement protocol (ISMA 2020).


    • Straight root-shoot axis and oval shaped scutellum.


    • Solid, translucent white colored.

    Other Features

    • Embryo located on the dorsal surface of the caryopsis.

Identification Tips


Many Sorghum species, especially the cultivated types of Sorghum bicolor nothosubsp. drummondii (sudangrass), S. bicolor subsp. verticilliflorum (common wild sorghum), and S. ×almum (Columbus grass) have similar spikelet shapes and colour. S. halepense (johnsongrass) spikelets are generally smaller and more narrow than other Sorghum species.

The pair of spikelet stalks generally have narrow ends in cultivated S. b. nothosubsp. drummondii but are well-developed with cup-shaped tips in S. halepense, as well as in S. ×almum, and S. b. subsp. verticilliflorum.

Additional Botany Information



  • The inflorescence is an open panicle 10 – 50 cm long and 5 – 25 mm wide (Barkworth et al. 2003)
  • Spikelets mostly in pairs or at the end of each inflorescence branch in clusters of three.

Vegetative Features

  • Sorghum halepense is a rhizomatous perennial.
  • Stems 50 – 200 cm tall (Barkworth et al. 2003).

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.


Sorghum ×almum Parodi

[Sorghum bicolor (L.) Moench × S. halepense L.]

Almum grass (English) (Wiersema and León 1999)
Almum sorghum (English) (Wiersema and León 1999)
Columbus grass (English) (Wiersema and León 1999)
Sorgho d’Argentine (French) (Wiersema and León 1999)
Columbusgras (German) (Wiersema and León 1999)
Sorgo almo (Italian) (ISTA 1982)
Sorgo negro (Spanish) (Wiersema and León 1999)

Sorghum ×almum is a rhizomatous perennial plant but the root system is generally less extensive than S. halepense (Gould 1975). Native to Argentina, Paraguay, and Uruguay, it is sometimes grown as a forage grass in the southern United States. However, Sorghum ×almum is classified as a noxious weed species in at least 12 U.S. states (USDA-AMS 2022) and is considered a harmful weed in China and New Zealand (USDA-PCIT-PExD 2021). The dispersal units of S. ×almum are very similar to S. halepense in colour and shape. The sessile spikelets can be slightly larger than S. halepense. Disarticulation of dispersal units is usually by abscission and the attached spikelet stalks have cup-shaped tips.

Size range measurements (D. Meyer*):
• Spikelet length: 4.5 – 6 mm, average 5.3 mm; width: 1.9 – 2.7 mm, average 2.3 mm.
• Stalk length: 0.9 – 3.3 mm, average 2.1 mm.
• Caryopsis length: 2.7 – 3.8 mm, average 3.3 mm; width: 1.6 – 2.2 mm, average 2.0 mm.
• Embryo length: 1.3 – 2.2 mm, average 1.9 mm.

* Notes: minimum and maximum based on 38 spikelets and 11 caryopses in a normal range of this species using image measurement protocol (ISMA 2020).


Sorghum bicolor (L.) Moench nothosubsp. drummondii (Steud.) de Wet ex Davidse

[Sorghum ×drummondii (Steud.) Nees ex Millsp. & Chase; Sorghum bicolor (L.) Moench subsp. drummondii (Steud.) de Wet ex Davidse; Sorghum bicolor (L.) Moench var. drummondii (Steud.)  Mohlenbr.; Sorghum sudanense (Piper) Stapf; for additional synonyms refer to USDA-ARS, 2021]

Sudangrass (English) (AOSA 2021)
Sudan grass (English) (Wiersema and León 1999)
Sorgho du Soudan (French) (Wiersema and León 1999)
Sorgho menu (French) (Wiersema and León 1999)
Sudangras (German) (Wiersema and León 1999)
Pasto Sudán (Spanish) (Wiersema and León 1999)

Sorghum bicolor nothosubsp. drummondii is an annual plant, cultivated mainly as a forage crop (Tutin et al. 1980; Wiersema and León 1999). The spikelets are generally larger than S. halepense, and the glumes range in colour from yellow, red, light brown, dark purplish brown depending on the cultivar. The spikelets are tardily separated from the inflorescence, usually by fracture. The spikelet stalks (rachis and pedicel) attached to the sessile spikelets are of inconsistent lengths because the tips are broken off during dispersal (rather than separation by abscission forming the well-developed cups at the ends of the stalks as in S. halepense). The caryopses are longer and wider than those of S. halepense.

Size range measurements (D. Meyer*):
• Sessile spikelet length: 4.8 – 6.8 mm, average 5.8 mm; width: 2.0 – 3.0 mm, average 2.5 mm.
• Caryopsis length: 3.2 – 5.3 mm, average 4.1 mm; width: 1.8 – 2.8 mm, average 2.2 mm.
• Embryo length: 1.9 – 3.9 mm, average 2.7 mm.

* Notes: minimum and maximum based on 40 spikelets and 39 caryopses in a normal range of this species following ISMA image measurement protocol (ISMA 2020).

Size range based on measurements (CFIA**)
• Sessile spikelet length: 5.0 – 6.0 mm; width: 2.0 – 3.0 mm.

**Notes: minimum and maximum of 10 spikelets in a normal range of this species using specimen measurement (ISMA 2020).

Additional size information for S. b. nothosubsp. drummondii from literature:

• Sessile spikelet length: 6 -7.5 mm (Tutin et al. 1980)

Additional note on cultivated hybrid crosses of grain sorghum and sudangrass (i.e., S. bicolor subsp. bicolor × S. bicolor nothosubsp. drummondii, sorghum-sudangrass hybrid): These hybrids are used as forage crops. Dispersal units of such hybrid crosses can have characteristics of both parents or can have a similar appearance to one or the other parent.


Sorghum bicolor (L.) Moench subsp. verticilliflorum (Steud.) de Wet ex Wiersema & J. Dahlb.

[Sorghum bicolor (L.) Moench ssp. arundinaceum (Desv.) de Wet & Harlan; Sorghum verticilliflorum (Steud.) Stapf]

Common wild sorghum (English) (USDA-ARS 2021)

Sorghum bicolor subsp. verticilliflorum is a wild annual relative of cultivated grain sorghum (Sorghum bicolor subsp. bicolor) that is native to Africa and Madagascar. The subspecies has been introduced to North, Central, and South America, Australia, and India. Common wild sorghum is considered a harmful weed in Honduras (USDA-PCIT-PExD 2021). The spikelets of common wild sorghum are generally longer than those of Sorghum halepense and the two attached stalks usually differ in width (one thick and one thin), whereas the two attached stalks of S. halepense are similar in width.

Size range measurements (D. Meyer*):
• Sessile spikelet length: 6.0 – 7.1 mm, average 6.5 mm; width: 1.9 – 2.6 mm, average 2.3 mm.

* Notes: minimum and maximum based on 15 spikelets in a normal range of this species following ISMA image measurement protocol (ISMA 2020).


Comparison of similar species (based on Meyer measurements)

Sorghum halepense Sorghum ×almum Sorghum bicolor nothosubsp. drummondii Sorghum bicolor subsp. verticilliflorum
Sessile spikelet length 1.8 – 6.3 mm 4.5 – 6 mm 4.8 – 6.8 mm 6.0 – 7.1 mm
Sessile spikelet width 1.6 – 2.6 mm 1.9 – 2.7 mm 2.0 – 3.0 mm 1.9 – 2.6 mm
Type of disarticulation Complete abscission Complete abscission Fracture Complete abscission
Caryopsis length 2.4 – 3.2 mm 2.7 – 3.8 mm 3.2 – 5.3 mm NA
Caryopsis width 1.6 – 1.9 mm 1.6 – 2.2 mm 1.8 – 2.8 mm NA
Embryo length 1.4 – 2.2 mm 1.3 – 2.2 mm 1.9 – 3.9 mm NA

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Deborah J. Lionakis Meyer ², Jennifer Neudorf ¹, Angela Salzl ¹, Ruojing Wang ¹, Karen Castro ¹, Katrina Entwistle ¹

¹ Canadian Food Inspection Agency

² California Department of Food & Agriculture (retired)