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Submit a photoPurple Loosestrife
Lythrum salicaria
⚠️ PROHIBITED NOXIOUS — must be destroyed under Alberta's Weed Control Act. A tall perennial (1–2 m) from Europe with dense spikes of magenta-purple flowers in mid-to-late summer. Extraordinarily destructive to wetlands — a single plant produces 2.7 million seeds per year and transforms diverse marshes into useless monocultures, crowding out cattails, rushes, and waterfowl nesting habitat. Was sold in Alberta nurseries for decades before being banned.
Quick Facts
Distribution
Scattered across Alberta wetlands; report all sightings
Light
Full sun to part shade (wet)
Bloom Time
July–Sept
Soil
Wet mud, pond edges, ditches
Water
High
Growing & Cultivation
Propagation
DO NOT PROPAGATE. Control: dig small infestations (bag and landfill all plant material including the thick root crown); biological control weevils are released for large infestations via Alberta Environment.
