Status: Declared Noxious Weed (Regionally Controlled).
Threat: High threat environmental and agricultural weed.
Description: An erect annual or biennial spiny thistle often growing up to 2 metres tall. Usually flat rosette of hairy leaves with spiny edges in its first year, before producing a flower stem and dying after seeding in its second year.
Flowers: Pinkish-purple flowers that are surrounded by green, cottony, long spiny bracts. Flower heads are usually in clusters of one to three at the end of branches. Flowers spring to autumn.
Leaves: Rosette leaves dense bristly up to 30cm long. Stem leaves are spine-tipped and have spiny leaf blades that extend along length of stem. Upper leaf surface is dark green and bristly, sometimes with small prickles, lower leaf surface is white and woolly. Stems are branched towards the top, hairy and spiky.
Fruits: Densely packed in bulbous head. Splits to release multiple seeds attached to pappus (hairy attachment) to aid wind dispersal.
Roots: Thick branched taproot which grows rapidly in first winter.
Note: Readily colonises disturbed, high fertility soils or overgrazed areas via wind, water or attached to animals.
Control measures: Hand weeding, spot spraying, slashing, pasture improvement.
Dispersal: Birds, animals, machinery, seeds, vegetative.