Alberta Invasive Plant Identification Guide
Alberta Invasive Plant Identification Guide
Alberta Invasive Plant Identification Guide
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Knapweed, Spotted<br />
Centaurea stoebe, Asteraceae (Sunflower Family)<br />
Category: Prohibited Noxious<br />
• Information: Introduced from Europe, covers vast areas of land in<br />
Canada and in the USA, found in disturbed areas, is allelopathic (toxic to-<br />
wards other plants).<br />
• Life cycle: Biennial or short-lived perennial.<br />
• Root: Taproot.<br />
•Leaves: Rosette leaves are deeply lobed, grayish green, and up to 15cm<br />
long. Stem leaves finely divided into linear segments.<br />
• Stems: Up to 120cm tall and highly branched.<br />
• Flower: One pinkish-purple flower head on each branch. Bracts have<br />
dark spot on tip and fringed edges.<br />
• Seed/Fruit: Black seeds 2mm long. Prolific seed producer.<br />
• Control: Long term, hand pick in rosette stage, chemical control before<br />
seed has set.<br />
Sarah Schumacher, Wheatland County<br />
Sarah Schumacher, Wheatland County<br />
34<br />
Montana State University <strong>Invasive</strong> <strong>Plant</strong> <strong>Identification</strong> <strong>Guide</strong> Montana State University <strong>Invasive</strong> <strong>Plant</strong> <strong>Identification</strong> <strong>Guide</strong>