Purple star thistle
Centaurea calcitrapa
Family · Asteraceae · Poisonous
Read this before the sheet
This plant, or one that resembles it, is dangerous. Identifying is not authorising: no app has the authority to tell you that you may eat or touch a plant.
The thistle whose spines are long, straight and stiff as steel needles, set in a star round each head. It goes through a trainer sole and is the worst thistle to walk among.
Roadsides and waste ground · Fields and pasture · Town and roadside
Also known asred star thistle, caltrop
How to tell it
A very branched, stiff, whitish plant growing into a ball shape. Small heads with purple or lilac florets. Each bract ends in a yellowish spine two to three centimetres, stiff and sharp, with smaller spines at its base. The Latin name means foot trap.
What it is confused with
No dangerous lookalikes known in the Iberian Peninsula.
What it is for
No use. The practical warning applies: it grows on verges and trodden paths and its spines pierce light footwear and lodge in a dog's skin. Where there is one there are dozens, and it is a case for going around.