Several helpful prairie fans from GardenWeb have now tentatively identified our mystery thistles. See if you can identify them from the photos below. For the answers, follow the link to GardenWeb's Prairie and Meadow Forum at the bottom of this page. Find the thread I began entitled, "Thistle Battleplan."
Our site's history: This is a 2.7 acre field surrounded by woodland and steep ravines on three sides. Before being seeded to prairie plants it was an agricultural field for many years (corn, soybeans, alfalfa). Prior to that it was an orchard (probably until the late 50's). The field was planted to prairie grasses and forbs in autumn of 2001. The prairie species are growing robustly.
We have two species of thistles growing in our prairie planting. One is quite isolated. We've found less than half a dozen specimens. The other thistle grows in patches of 20 to 100 individuals. I (Jim) used to believe that I knew my thistles, but after doing lots of web research, I've become confused!
We don't wish to eradicate any rare species, so we invite viewers to view and identify my thistles. We can email the photos to you if it's inconvenient for you to view them here.
We have found about half a dozen of the above-pictured plants. They are up to two feet in diameter. As of early June, height is between one and two feet. These are the thistles believed to be Canada Thistle, however, some web sources show a very different looking plant which they identify as Canada Thistle.
We don't know what this thistle is, but there are many patches of it, which we have been battling. This plant gets about 2 1/2 feet tall. Early in the season, we spot treated them with Roundup, but as seed heads began to form we took to cutting them at ground level or below or pulling them. When pulled, these thistles usually reveal four to six inches of thick taproot.
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