Allium Triquetrum

(See May 13th)
We had message on the street email today warning neighbours about these plants which I blipped just four days ago. Apparently they are an invasive species which are to be rooted out wherever they appear!! It is an offence to plant them in the wild. The seeds are dispersed by ants - but no information about where they originated. However .... I still think they are rather atttractive!!