Along the canal towpath I came across this beauty.
The Flower forum identified it for me as Purple Loosestrife.
The Wildlife Trusts website says it's "a valuable food source for long-tongued insects like bees, moths and butterflies, including Brimstones, Red-tailed Bumblebees and Elephant Hawk-moths." Apparently it's rare in Scotland, apart from the West Coast, which probably explains why I've not noticed it before.
Googling says that it is invasive in British Columbia, so obviously not welcome everywhere.
