The seeds of the Creeping Thistle are about to get airborne. All it will take now is the slightest of wind puffs and they are on their way. This inflorescence almost looks like it has a bad hair day. But it will not last. Soon the seeds will be gone with the wind. Each Creeping Thistle plant can produce thousands of seeds at the end of the summer. In addition to reproducing using wind-dispersed seeds, the Creeping Thistle also reproduced vegetatively by creeping roots (rhizomes). These two reproductive methods result in the plant being a formidable weed that, once established, is virtually impossible to eliminate. It often invades crop fields and grasslands where it lowers crop yields and forage productivity.
The Creeping Thistle inflorescences, which are everywhere along forest edges and open fields, are slowly undergoing a metamorphosis from pretty fuzzy purple flowers to mangy-looking fuzzy grey bunches of seed. The seeds have a feathery appendage, aka as a pappus, that enable the seed to be carried by the wind. Wind dispersed seeds is, however, only one trick the Creeping Thistle has up its sleeve when it comes to reproducing. It is also able to make new copies of itself by reproducing vegetatively by developing an extensive lateral root system.
Another pretty flower with an insidious secret. We came across the Creeping Thistle the other day just off the Whitemud Creek as we were on a nature bike ride. Just like other recent pretty flowers we have come across (for example, Cow Vetch, Red Clover and Meadow Buttercup) the Creeping Thistle is an invasive weed that was introduced from Europe and Asia. To add insult to the injury it is often referred to as Canada Thistle, which is of course misleading since it is not of Canadian origin. As far as I can tell, it was introduced in North America accidentally, most likely as a contaminant in crop seeds. There used to be a Thistle Patrol here in Edmonton that went around to natural areas pulling out creeping thistles. Although there are effective herbicides that kill the plant they also kill the native plant, so the incentive behind the Thistle Patrol was to remove this invasive weed manually to avoid the need for spraying herbicides. I have not been able to find any information about the Thistle Patrols activities these days (most recently they seemed to be active in 2013), perhaps the patrol has retired. Did they “win” the battle against the Creeping Thistle or was it too big of a job to keep up with? Who knows?