Onopordum illyricum is a species of thistle known by the common name Illyrian thistle, or Illyrian cottonthistle. It is native to southwestern Europe, but has been introduced into Australia and California, where it has become a noxious weed.
The plant is a biennial herb producing an erect, branching, winged, spiny stem known to exceed two meters in maximum height. The spiny leaves may be up to 50 centimetres (20 in) long and are divided into deep toothed lobes.
The inflorescence bears several large flower heads each up to 7 centimetres (3 in) wide. They are lined with spiny, woolly to cobwebby phyllaries and bear many narrow glandular purple flowers each about 3 centimetres (1.2 in) long. The fruit is a cylindrical achene 4 or 5 millimetres (0.16 or 0.20 in) long topped with a white pappus 1 centimetre (0.39 in) in length.
This plant might be poisonous
How to get rid of:
Prescribed measures for the control of noxious weeds:
application of a registered herbicide or physical removal.
Physical removal aims to remove the entire plant, including its roots, from the soil, therefore reducing the above-ground plant-mass before follow up methods are applied.
This can be achieved by 'grubbing' out by hand or, if the plant is large enough, removal by machinery, (tractor and chain, bobcat, or excavator fitted with a grab bucket).
All root systems should be removed, as some plants will re-shoot from roots left in the ground.
Removal by hand is only suitable for machinery hygiene.