Canada thistle is found in every county in Montana. It can reach heights of up to four feet and has extensive root systems, which make it very difficult to control. The flowers resemble those of spotted knapweed. Both female and male flowers must be present for the plant to go to seed. One plant can produce over 3,000 seeds annually, but it spreads primarily from the roots.
Canada Thistle
May 2, 2012 By