⚠️
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Submit a photoSpotted Knapweed
Centaurea stoebe
⚠️ NOXIOUS — a short-lived perennial from the Balkans with deeply lobed grey-green leaves, and pink-purple thistle-like flower heads with distinctive black-tipped bracts (the 'spots'). Allelopathic — exudes catechin from roots that suppresses native plant growth. Has devastated millions of hectares in Montana; active spread in Alberta. Each plant produces 1,000+ seeds.
Quick Facts
Distribution
Scattered in southern Alberta rangeland; spreading
Light
Full sun
Bloom Time
July–Aug
Soil
Well-drained; prefers sandy or gravelly rangeland
Water
Low
Pet Safe— Generally considered safe around pets.
Growing & Cultivation
Propagation
DO NOT PROPAGATE. Control: herbicide in rosette stage; biological control flies and weevils (Larinus spp., Cyphocleonus achates) available.
