Allium Triquetrum (more commonly known as three-cornered garlic) is a lovely looking plant.
With an appearance very similar to bluebells, in a different colour, it really stands out in a garden.
However, its appearance is not the only thing that stands out - the smell does too!
Again, like Japanese knotweed, it was introduced during the Victorian era, circa 18th Century.
It loves to spread through seed/bulbs and when established forms dense clumps of leaves with three corners like a triangle. Three-cornered garlic can also be quite invasive when it takes hold and as already mentioned, has a rather garlicky overpowering smell.
Herbicide treatment can be effective and the best time to treat is before the plant flowers - from mid April generally. Here are some photos from one property with three-cornered garlic on site:
Last year, the plant was choking out other plants in the garden...
This year, three cornered garlic is still present, but the quantity has significantly reduced (over 50%) since the first year...
Another herbicide application will be required next year and we will continue to treat it until there is no further regrowth!