Centaurea calcitrapa is an annual or biennial species of flowering plant native to southern and western Europe. It has been introduced to New Zealand. This noxious weed is found in Northland, East Cape, King Country, Hawkes Bay Marlborough, Canterbury, Otago and the Chatham Islands. Its habitat is roadsides, waste places and pastures.
Centaurea calcitrapa starts life as a tap-rooted rosette. During November and March it produces an erect, branched and hairy flower stems up to 1.3 m tall. The lowermost leaves may reach a length of 20 centimetres and are deeply lobed. Between November and April, it produces pink-purple, 8 mm in diameter flower heads that have vicious spines around them.

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Centaurea calcitrapa (Star thistle)