Canadian Thistle

Canada Thistle

Interesting Facts

Contrary to the name, Canada thistle did not come into the U.S. from our northern neighbor, but rather was introduced in the 17th century from the Mediterranean region and southeast Europe.
Tea made from Canada thistle leaves has been used as a diuretic as well as for treatment of tuberculosis
It is the only thistle with male and female flowers on separate plants
Roots can branch out to 15 ft. wide and deep.
Seeds are winged and are easily dispersed by wind
New plants can develop from small broken pieces of the plant
Disperses a chemical that may inhibit growth of other plants
Seed may remain viable in soil up to 20 years

Description:

Canada thistle is an herbaceous perennial in the aster family with erect stems, prickly leaves, and an extensive creeping rootstock.

Stems are branched, often slightly hairy, and ridged
Leaves are lance-shaped, irregularly lobed with spiny, toothed margins and are borne singly and alternately along the stem
Flowers are rose-purple, lavender, or sometimes white flower and occur in rounded, umbrella-shaped clusters
Seeds are tan curved and has a papery covering

Habitat

Canada thistle is found in open areas with a moderate amount of moisture but does poorly on wet soils lacking sufficient oxygen. It can grow on many different soil types but it does not grow well in shade and is rarely found within wooded sites, except in clearings. It is commonly found in abandoned fields or lots, abandoned gravel pits, pastures, right-of-ways, roadsides, railway embankments, lawns, gardens, and agricultural fields. It also invades wet areas with fluctuating water levels such as stream banks or irrigation ditches and sloughs.