I, in Fife, have been invaded by an antipodean weed that is considered to be an invasive alien species in the UK.
I am not certain of its true identy as different websites conflict with each other.
Some say it is the Piri Piri Bur or Bidi Bidi or Biddy Biddy (Acaena novae-zelandiae)
but others give a close relative as the culprit: Piri-piri Burr, (Acaena aserinifolia)
Either way, it spreads rapidly over poor soils and produces sharp-pointed burs (like arrow-heads) that catch in the fur of pets and feathers of birds (eg gulls) and is being distributed far and wide.
It is currently a recognised nuisance on Holy Island (Lindisfarne) and nearby sand dunes.It is now an unrecognised nuisance in my garden and down the lane that runs parallel to our street.
Here is a close-up blip of its arrow-head bur that I photographed in Australia last year.
April 21st 2011
This plant is related to our native Salad Burnet (Sanguisorba minor)