Identification : Originally from Eurasia, Canada thistle is an aggressive,
colony-forming, creeping perennial weed that develops from seed or vegetative
buds in its root system. Horizontal roots(rhizomes) my extend 15 feet
and vertical roots may grow 6 to 15 feet deep.
It emerges from its root system in mid- to late-spring and forms rosettes.
Plants grow from 1 to 4 feet in height.Flowers are unisexual, small
and are lavender to purple(sometimes white) in color. Leaves are green,
alternate, crinkly, and have well developed sharp spines along their
edges. Canada thistle begins to flower in late spring to early summer
and may produce, on average, 1,000 to 1,500 seeds per plant.
The small, dry, single-seeded fruits(achenes) have a white feathery
structure attached to the seed base. Seeds may be transported long distances
by wind, water, by being attached to animals, clothing, farm equipment
and other vehicles, or with contaminated crop seed. Canada thistle is
common throughout Adams County.