Fact Sheets


Chondrilla juncea L.

Family :

Famille :


Synonym(s) :

Synonyme(s) :

Common Name(s) :

Nom(s) commun(s) :

Rush skeletonweed
(English) (GC 2016)
Chondrille (French) (GC 2016)
Skeletonweed (English) (AOSA 2019)
Devil’s grass (English) (CABI 2020)
Gum succory (English) (CABI 2020)
Hogbite (English) (CABI 2020)
Yuyo esqueleto (Spanish, Argentina) (CABI 2020)
Achicoria juncal (Spanish, Spain) (CABI 2020)
Binsenknorpellattich (German) (CABI 2020)

  • Chondrilla juncea (rush skeletonweed) achenes

  • Rush skeletonweed (Chondrilla juncea) achenes

  • Rush skeletonweed (Chondrilla juncea) achene

  • Chondrilla juncea (rush skeletonweed) achene with pappus

  • Chondrilla juncea (rush skeletonweed) seed head

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Regulation :

Remarques Réglementation:

  • CFIA Weed Seeds Order - Class 2: Primary Noxious Weed Seeds

Regulation Notes:

Distribution :

Répartition :

Native to northern Africa, temperate Asia and Europe. Introduced to North America, Argentina, Latvia, Australia and New Zealand (USDA-ARS 2020). Infests millions of acres in Washington, Idaho, Oregon and California (FNA 1993+). Occurs in Canadian provinces of British Columbia and Ontario (Brouillet et al. 2010+).

Habitat and Crop Association :

Habitat et Cultures Associées :

Cultivated fields, pastures, rangelands, forests, roadsides and disturbed areas (Darbyshire 2003). A serious weed of Triticum aestivum (wheat) in Australia (FNA 1993+).

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


Chondrilla juncea was first reported in the United States near Spokane, Washington in 1938 (Sheley 1994), and is now found in the northern regions and California (Kartesz 2015). C. juncea is often found on well-drained, light soils (Shaw et al. 2008).

One plant may produce as many as 15,000 – 20,000 seeds (BC MAFF 2002). Seeds are dispersed by wind and animals over considerable distances (Shaw et al. 2008).


Chondrilla juncea infestation (Eric Coombs, Oregon Department of Agriculture, Bugwood.org)



  • Achene


    • Achene length* (without style remnant): 3.5 – 4.4 mm; width: 0.6 – 0.8 mm
    *Note: minimum and maximum of 10 achenes in a normal range of this species using image measurement (ISMA 2020)


    • Achene is wedge shaped, generally compressed at wider end, tapering to a narrow cylindrical end

    Surface Texture

    • Smooth surface with 5 wide, longitudinal ribs and narrow grooves between them


    • Achene is generally dull or shining straw yellow, can be light yellow or yellowish brown

    Other Features


    • Umbrella-like pappus of long hairs (5.0 – 6.0 mm, FNA 1993+) attached to a stalk is at the end of intact achenes

    Achene end with pappus

    • A thin remnant style extends up to 6.0 mm (FNA 1993+)
    • Remnant style is easily broken off
    • Flattened spines present at one end near the style remnant, and are generally broken during seed processing

    Achene end without pappus

    • The longitudinal ribs extend the length of the achene and are separate at the end
  • Seed


    • Seed is similar to achene size, fills the fruit interior


    • Seed is elongate, tapered at one end and truncate at the other

    Surface Texture

    • Seed is smooth or wrinkled


    • Seed is yellow

    Other Features

    • A thin, translucent, flexible seed coat loosely surrounds the seed
  • Embryo


    • Embryo fills the seed


    • Embryo is spatulate, axial position


    • Endosperm is scant, nutritive tissue stored in the cotyledons

    Other Features

    • Cotyledons are oily and soft textured

Identification Tips


The achene of Chondrilla juncea is compressed near the style remnant and cylindrical at the opposite end. The 5 ribs of the achene are separate at the ends. Similar achenes in the Asteraceae are compressed or angular along the entire length, and the ribs are partially or totally merged at the ends.

Additional Botany Information



  • Flower heads are cylindrical with long, straight involucral bracts; petals are yellow (FNA 1993+)


Vegetative Features

  • The stem and leaves leak white sap when broken (FNA 1993+)

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.

Taraxacum officinale F. H. Wigg. (dandelion)

T. officinale achenes are shorter and wider (length*: 2.6 – 3.9 mm; width: 0.9 – 1.4 mm), angular wedge-shaped generally wider, darker yellow-brown colour and the flat spines at the top extend further down the achene than Chondrilla juncea. The truncate, narrow end of T. officinale achenes have four ribs with alternating narrow grooves, while C. juncea has five ribs.

*Note: minimum and maximum of 10 achenes in a normal range of this species using image measurement (ISMA 2020)

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Association of Official Seed Analysts (AOSA). 2019. AOSA Rules For Testing Seeds. Volume 3: Uniform Classification of Weed and Crop Seeds. AOSA, Washington, DC.

British Columbia Ministry of Agriculture, Food and Fisheries (BC MAFF). 2002. Guide to weeds in British Columbia. Open Learning Agency, Burnaby, British Columbia, Canada. 195 pp.

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 November 23, 2020.

Centre for Agriculture and Bioscience International (CABI). 2020. Invasive Species Compendium, CAB International, Wallingford, UK. https://www.cabidigitallibrary.org/journal/cabicompendium Accessed November 23, 2020.

Darbyshire, S. J. 2003. Inventory of Canadian Agricultural Weeds. Agriculture and Agri-Food Canada, Research Branch. Ottawa, ON.

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

Global Biodiversity Information Facility (GBIF) Secretariat. 2022. https://doi.org/10.15468/39omei Accessed via https://www.gbif.org/species/8537667 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)

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

Kartesz, J. T. 2015. The Biota of North America Program (BONAP). North American Plant Atlas. Chapel Hill, N.C., www.bonap.org/MapSwitchboard.html Accessed November 23, 2020.

Shaw, N. L., Hild, A. L. and Kinter, C. L. 2008. Chondrilla juncea L. In: Post-fire invasiveness in Artemisia tridentata communities of western North America. Multifunctional grasslands in a changing world, Volume II; XXI International Grassland Congress; VIII International Rangeland Congress. Beijing, China: Guangdong People’s Publishing House: 808.

Sheley, R. L. 1994. The identification, distribution, impacts, biology, and management of noxious rangeland weeds. Plant, Soil, and Environmental Sciences, Montana State University, Bozeman, Montana. 318-329 pp.

U.S. Department of Agriculture-Agricultural Research Services (USDA-ARS). 2020. Germplasm Resources Information Network (GRIN), https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysimple.aspx Accessed November 23, 2020.



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

Canadian Food Inspection Agency