Habitat: pastures, crops, landscape areas throughout Ohio
Life cycle: perennial with creeping roots
Growth Habit: 1-3 feet high, erect, branched; forming large patches
Leaves: 3-8 inches long, alternate with spiny, crinkled margins; lower leaves are lobed
Stems: grooved and becoming hairy with age; not spiny; branched at apex
Inflorescence: Lavender flower heads about 1 inch wide and long. Flowers are surrounded by bracts without spiny tips.
Fruits: white feathery pappus
Roots: A creeping root system allows this weed to spread aggressively.
Hand-pulling and cultivation are often ineffective control mechanisms
because new plants sprout from root pieces that snap off.
Similar plants: Stems of Canada thistle are not spiny in contrast to bull thistle (Cirsium vulgare) and nodding thistle (Carduus nutans).
The problem is.... an aggressive, spreading root system. Very competitive with field crops and forages. Canada thistle is also prolific in seed production at 700 seeds per stem. Seeds are dispersed by wind and birds.
Canada thistle in flower. |
Canada thistle is a common weed in almost any situation. |
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