Lythrum salicaria

Purple loosestrife

Lythrum salicaria or purple loosestrife is a flowering plant belonging to the family Lythraceae. It should not be confused with other plants sharing the name loosestrife that are members of the family Primulaceae. Other names include spiked loosestrife and purple Lythrum. This herbaceous perennial is native to Europe and Asia, and possibly Australia.

Source: Wikipedia

[Lythrum salicaria] has invaded an enormous number of Canadian wetlands, including marshes, ponds and streams. The exotic, invasive plants threaten the ecological balance of conservation areas and can only be removed by digging.
(E) Emanations of other problems