Pirri-pirri bur (Acaena novae-zelandiae) is an invasive species concentrated in the dunes at Holy Island (an din parts of northern Ireland). Wily and sculptural little stick-ems that break into seedy pieces when you try and remove them. Would be fun to design a suit to take a walk in, ending up covered in these atomic wonders. But don’t turn your dog into a pirri-pirri-collecting artwork – it’s apparently very painful for the canines.

Pirri pirri is not a native to Britain and is thought to be originally from New Zealand, possibly brought over in shipped consignments of wool. During and just after the seeding time the tiny burrs are exceptionally sticky and very difficult to remove.
Apart from the damage to the dog there is also a real danger that the seeds come over to the mainland and set themselves in dunes or gardens. (Berwick Advisor)