Iberian starthistle (Centaurea iberica) is a problematic weed of the aster family (Asteraceae). It displaces valuable forage species in pastures and rangelands. Due to its sharp spines, infestations can deter grazing animals, impede recreational use and restrict access for wildlife.
Report an Iberian starthistle sighting
Where it's found
Iberian starthistle has not been found in Canada. It is native to Asia and southeastern Europe. In the United States, the species has been reported from the following states: California, Kansas, Oregon, Washington and Wyoming. However, the species has been eradicated in all states except California. Iberian starthistle grows in disturbed areas such as over-grazed rangelands, fields and roadsides.
How to spot it
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Plant -
Stems and leaves -
Leaves and spines -
Flower and spines -
Seeds
Iberian starthistle is a biennial herbaceous plant with a stout taproot. Its stems grow from 30 to 200 cm tall. The leaves are divided into narrow leaflets. The flower heads are white, pink or pale purple and are surrounded by straw-coloured spines approximately 2.5 cm long. The seeds are white or brown-streaked, 3-4 mm long, and have a 1-2.5 mm plume of flat, white bristles.
How it spreads
Iberian starthistle seeds can scatter over very short distances with the wind. However, they are primarily spread by livestock, vehicles, equipment, clothing, and hay and crop seed.
What you can do
- Ensure machinery, vehicles and tools are free of soil and plant parts before moving them from one area to another
- Brush off clothing and clean footwear to avoid spreading seeds and plant material
- Use certified seed
- Use clean grain, hay and straw
- Maintain healthy and diverse pastures
- If you think you've spotted Iberian starthistle, report it to the Canadian Food Inspection Agency (CFIA). The CFIA will follow up and determine if further action is needed.
What we are doing
Iberian starthistle is regulated as a pest in Canada under the Plant Protection Act. It is also listed as a prohibited noxious weed in the Weed Seeds Order, 2016 under the Seeds Act. Importation and domestic movement of regulated plants and their propagative parts is prohibited.