They produce abundant seeds, plus spread through their roots [rhizomes]. "New plants pop up from the roots, so where you had one Canada thistle last year, you might have 30 this year, and they are ...

The Californian thistle can be very competitive in crops, establishing quickly in a new crop from old root systems. Californian thistle is also well-adapted to growing in situations such as asparagus ...

For more information visit Midwest Invasive Species Information Network (MISIN). Canada thistle forms extremely extensive root systems that need to be repeatedly damaged to keep them from growing back ...

Scotch thistle is the most common thistle species in New Zealand with spines on both the leaf surface and margins. Scotch thistle is a biennial weed, so it depends quite heavily on the establishment ...