Iberian starthistle – Centaurea iberica

Weed Seed - Iberian Starthistle (Centaurea iberica)

Iberian starthistle is an invasive plant that 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.

Where it's found

Iberian starthistle has not been found in Canada. It is native to Asia, India and south-eastern Europe. In the United States, Iberian starthistle has been found in California, Kansas, Oregon, Washington and Wyoming. Iberian starthistle seems to grow only in disturbed areas, including over-grazed rangelands.

What it looks like

Iberian starthistle is a biennial, herbaceous plant. The stems grow from 30 cm to 2 m tall. The leaves are divided into narrow leaflets. The flower heads are white, pink or pale purple, and are surrounded by straw-colored spines more than 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, but most spread through livestock, vehicles, equipment and contaminated hay and crop seed. Seeds can also be transported on clothing.

Legislation

Iberian starthistle is regulated as a pest in Canada under the Plant Protection Act. It is also listed as a prohibited noxious weed on the Weed Seeds Order, 2016 under the Seeds Act. Importation and domestic movement of regulated plants and their propagative parts is prohibited.

What you can do about it

  • Maintain healthy and diverse pastures.
  • Use clean, high-quality seed that is certified if possible.
  • Ensure machinery, vehicles and tools are free of soil and plant parts.
  • Contact your local Canadian Food Inspection Agency (CFIA) office if you suspect you have found this invasive plant. The CFIA will follow up and determine if further action is needed.

To find out more, visit www.inspection.gc.ca/invasive.

Iberian starthistle flower
Iberian starthistle flower
Attribution: Todd Mervosh, Connecticut Agricultural Experiment Station
Iberian starthistle plant
Iberian starthistle plant
Attribution: (CDFA)/Integrated Pest Control
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